From f944ee763d7812a6471df2ffba8e9893f40509aa Mon Sep 17 00:00:00 2001
From: Alex Arslan <ararslan@comcast.net>
Date: Thu, 1 Mar 2018 16:05:39 -0800
Subject: [PATCH] Deprecate contains to a more general isfound function

While `contains` was generally limited to strings and regular
expressions (after the move from `ismatch` to `contains`), `isfound`
works more generally, as its fallback method is defined in terms of
`findfirst`.
---
 DISTRIBUTING.md                               |   2 +-
 NEWS.md                                       |   2 +
 base/array.jl                                 |  22 ++++
 base/client.jl                                |  10 +-
 base/deprecated.jl                            |   6 +-
 base/exports.jl                               |   2 +-
 base/libc.jl                                  |   2 +-
 base/loading.jl                               |  18 +--
 base/methodshow.jl                            |   2 +-
 base/mpfr.jl                                  |   2 +-
 base/path.jl                                  |  10 +-
 base/regex.jl                                 |   6 +-
 base/strings/search.jl                        |  27 +----
 base/uuid.jl                                  |   2 +-
 base/version.jl                               |   6 +-
 contrib/add_license_to_files.jl               |   2 +-
 contrib/fixup_precompile.jl                   |   6 +-
 doc/src/base/arrays.md                        |   1 +
 doc/src/base/strings.md                       |   1 -
 doc/src/manual/strings.md                     |  26 ++--
 stdlib/DelimitedFiles/src/DelimitedFiles.jl   |   2 +-
 stdlib/Distributed/test/distributed_exec.jl   |   4 +-
 .../InteractiveUtils/src/InteractiveUtils.jl  |   6 +-
 stdlib/InteractiveUtils/test/runtests.jl      |  22 ++--
 stdlib/LibGit2/test/libgit2.jl                |  16 +--
 stdlib/Libdl/test/runtests.jl                 |   6 +-
 stdlib/LinearAlgebra/src/blas.jl              |   2 +-
 stdlib/LinearAlgebra/src/uniformscaling.jl    |   2 +-
 stdlib/LinearAlgebra/test/triangular.jl       |  16 +--
 stdlib/Markdown/src/Common/block.jl           |  10 +-
 stdlib/Markdown/src/Common/inline.jl          |   2 +-
 stdlib/Markdown/src/render/plain.jl           |   2 +-
 stdlib/Markdown/src/render/rst.jl             |   2 +-
 .../src/render/terminal/formatting.jl         |   2 +-
 stdlib/Markdown/test/runtests.jl              |  22 ++--
 stdlib/Pkg/src/read.jl                        |   6 +-
 stdlib/Pkg/src/reqs.jl                        |   6 +-
 stdlib/Pkg/test/pkg.jl                        |  46 +++----
 stdlib/Pkg3/bin/utils.jl                      |   2 +-
 stdlib/Pkg3/src/Operations.jl                 |   2 +-
 stdlib/Pkg3/src/Pkg2/reqs.jl                  |   6 +-
 stdlib/Pkg3/src/PlatformEngines.jl            |   2 +-
 stdlib/Pkg3/src/REPLMode.jl                   |   6 +-
 stdlib/Pkg3/src/Types.jl                      |   4 +-
 stdlib/Pkg3/test/pkg.jl                       |   2 +-
 stdlib/REPL/src/REPLCompletions.jl            |   4 +-
 stdlib/REPL/src/docview.jl                    |   2 +-
 stdlib/REPL/src/latex_symbols.jl              |   2 +-
 stdlib/REPL/test/repl.jl                      |  57 +++++----
 stdlib/REPL/test/replcompletions.jl           |   2 +-
 stdlib/Serialization/test/runtests.jl         |   4 +-
 stdlib/SparseArrays/test/sparsevector.jl      |   6 +-
 stdlib/SuiteSparse/test/cholmod.jl            |   4 +-
 stdlib/Test/src/Test.jl                       |   4 +-
 stdlib/Test/src/logging.jl                    |  14 +--
 stdlib/Test/test/runtests.jl                  | 103 ++++++++--------
 test/backtrace.jl                             |   2 +-
 test/char.jl                                  |   2 +-
 test/cmdlineargs.jl                           |  32 ++---
 test/codegen.jl                               |  52 ++++----
 test/compile.jl                               |   6 +-
 test/compiler/compiler.jl                     |   2 +-
 test/core.jl                                  |   6 +-
 test/deprecation_exec.jl                      | 114 +++++++++---------
 test/dict.jl                                  |   8 +-
 test/docs.jl                                  |   6 +-
 test/env.jl                                   |   4 +-
 test/errorshow.jl                             |  76 ++++++------
 test/goto.jl                                  |   2 +-
 test/llvmcall.jl                              |   2 +-
 test/llvmcall2.jl                             |   2 +-
 test/logging.jl                               |   6 +-
 test/math.jl                                  |   2 +-
 test/misc.jl                                  |  20 +--
 test/mpfr.jl                                  |   2 +-
 test/offsetarray.jl                           |   4 +-
 test/osutils.jl                               |   4 +-
 test/reduce.jl                                |   8 +-
 test/reflection.jl                            |  12 +-
 test/regex.jl                                 |   2 +-
 test/show.jl                                  |  71 +++++------
 test/spawn.jl                                 |   4 +-
 test/stacktraces.jl                           |   4 +-
 test/staged.jl                                |   8 +-
 test/strings/search.jl                        |   8 +-
 test/strings/types.jl                         |   4 +-
 test/threads.jl                               |   4 +-
 test/worlds.jl                                |   2 +-
 88 files changed, 516 insertions(+), 520 deletions(-)

diff --git a/DISTRIBUTING.md b/DISTRIBUTING.md
index 74dc01c0bf6448..2b0c1a83f57cbd 100644
--- a/DISTRIBUTING.md
+++ b/DISTRIBUTING.md
@@ -364,7 +364,7 @@ for result in eachrow(results)
     b = result[:backport]
     if (isna(a) && !isna(b)) || (isna(b) && !isna(a))
         color = :yellow
-    elseif a != b && contains(b, "pass")
+    elseif a != b && isfound("pass", b)
         color = :green
     elseif a != b
         color = :red
diff --git a/NEWS.md b/NEWS.md
index 190a456e62bb3b..c87f16568d9bb3 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1067,6 +1067,8 @@ Deprecated or removed
   * The `remove_destination` keyword argument to `cp`, `mv`, and the unexported `cptree`
     has been renamed to `force` ([#25979]).
 
+  * `contains` has been deprecated in favor of a more general `isfound` function ([#26283]).
+
   * The methods of `range` based on positional arguments have been deprecated in favor of
     keyword arguments ([#25896]).
 
diff --git a/base/array.jl b/base/array.jl
index 16c23f862ecfb4..f3203a0379720e 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1684,6 +1684,28 @@ end
 findfirst(testf::Function, A::Union{AbstractArray, AbstractString}) =
     findnext(testf, A, first(keys(A)))
 
+"""
+    isfound(needle, haystack)
+
+Determine whether `needle` is found within `haystack`. This function is effectively
+equivalent to `findfirst(needle, haystack) !== nothing`.
+
+See also [`findfirst`](@ref) and [`any`](@ref).
+
+# Examples
+```jldoctest
+julia> isfound('x', "hexonxonx")
+true
+
+julia> isfound("hi", "hi mom")
+true
+
+julia> isfound(equalto(3), 5:10)
+false
+```
+"""
+isfound(needle, haystack) = findfirst(needle, haystack) !== nothing
+
 """
     findprev(A, i)
 
diff --git a/base/client.jl b/base/client.jl
index ca76fed2ed24bf..2631486cf9b251 100644
--- a/base/client.jl
+++ b/base/client.jl
@@ -244,11 +244,11 @@ incomplete_tag(ex) = :none
 function incomplete_tag(ex::Expr)
     Meta.isexpr(ex, :incomplete) || return :none
     msg = ex.args[1]
-    contains(msg, "string") && return :string
-    contains(msg, "comment") && return :comment
-    contains(msg, "requires end") && return :block
-    contains(msg, "\"`\"") && return :cmd
-    contains(msg, "character") && return :char
+    isfound("string", msg) && return :string
+    isfound("comment", msg) && return :comment
+    isfound("requires end", msg) && return :block
+    isfound("\"`\"", msg) && return :cmd
+    isfound("character", msg) && return :char
     return :other
 end
 
diff --git a/base/deprecated.jl b/base/deprecated.jl
index 9f90cf11e18583..b0db5a9bb231d9 100644
--- a/base/deprecated.jl
+++ b/base/deprecated.jl
@@ -1229,7 +1229,7 @@ end
 @deprecate rsearchindex(s::AbstractString, c::Char) findlast(equalto(c), s)
 @deprecate rsearchindex(s::AbstractString, c::Char, i::Integer) findprev(equalto(c), s, i)
 
-@deprecate ismatch(r::Regex, s::AbstractString) contains(s, r)
+@deprecate ismatch(r::Regex, s::AbstractString) isfound(r, s)
 
 @deprecate findin(a, b) findall(occursin(b), a)
 
@@ -1454,6 +1454,10 @@ function slicedim(A::AbstractVector, d::Integer, i::Number)
     end
 end
 
+# PR #26283
+@deprecate contains(haystack, needle) isfound(needle, haystack)
+@deprecate contains(s::AbstractString, r::Regex, offset::Integer) isfound(r, s, offset=offset)
+
 # Issue #25786
 @deprecate_binding DevNull devnull
 # TODO: When these are removed, also remove the uppercase variants in libuv.jl and stream.jl
diff --git a/base/exports.jl b/base/exports.jl
index b7d3241a7eeba1..c96c28c3b275da 100644
--- a/base/exports.jl
+++ b/base/exports.jl
@@ -447,7 +447,6 @@ export
     zeros,
 
 # search, find, match and related functions
-    contains,
     eachmatch,
     endswith,
     equalto,
@@ -460,6 +459,7 @@ export
     findmax!,
     findnext,
     findprev,
+    isfound,
     occursin,
     match,
     searchsorted,
diff --git a/base/libc.jl b/base/libc.jl
index b269e931416f99..41f329c262b184 100644
--- a/base/libc.jl
+++ b/base/libc.jl
@@ -203,7 +203,7 @@ function strptime(fmt::AbstractString, timestr::AbstractString)
     @static if Sys.isapple()
         # if we didn't explicitly parse the weekday or year day, use mktime
         # to fill them in automatically.
-        if !contains(fmt, r"([^%]|^)%(a|A|j|w|Ow)")
+        if !isfound(r"([^%]|^)%(a|A|j|w|Ow)", fmt)
             ccall(:mktime, Int, (Ref{TmStruct},), tm)
         end
     end
diff --git a/base/loading.jl b/base/loading.jl
index 0723313515a324..25ca69a859547c 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -388,7 +388,7 @@ function project_file_name_uuid_path(project_file::String,
         uuid = dummy_uuid(project_file)
         path = joinpath("src", "$name.jl")
         for line in eachline(io)
-            contains(line, re_section) && break
+            isfound(re_section, line) && break
             if (m = match(re_name_to_string, line)) != nothing
                 name = String(m.captures[1])
             elseif (m = match(re_uuid_to_string, line)) != nothing
@@ -407,7 +407,7 @@ function project_file_manifest_path(project_file::String)::Union{Nothing,String}
     open(project_file) do io
         dir = abspath(dirname(project_file))
         for line in eachline(io)
-            contains(line, re_section) && break
+            isfound(re_section, line) && break
             if (m = match(re_manifest_to_string, line)) != nothing
                 return normpath(joinpath(dir, m.captures[1]))
             end
@@ -494,9 +494,9 @@ function explicit_project_deps_get(project_file::String, name::String)::Union{Bo
         state = :top
         for line in eachline(io)
             if state == :top
-                if contains(line, re_section)
+                if isfound(re_section, line)
                     root_name == name && return root_uuid
-                    state = contains(line, re_section_deps) ? :deps : :other
+                    state = isfound(re_section_deps, line) ? :deps : :other
                 elseif (m = match(re_name_to_string, line)) != nothing
                     root_name = String(m.captures[1])
                 elseif (m = match(re_uuid_to_string, line)) != nothing
@@ -506,7 +506,7 @@ function explicit_project_deps_get(project_file::String, name::String)::Union{Bo
                 if (m = match(re_key_to_string, line)) != nothing
                     m.captures[1] == name && return UUID(m.captures[2])
                 end
-            elseif contains(line, re_section)
+            elseif isfound(re_section, line)
                 state = :deps
             end
         end
@@ -524,7 +524,7 @@ function explicit_manifest_deps_get(manifest_file::String, where::UUID, name::St
         uuid = deps = nothing
         state = :other
         for line in eachline(io)
-            if contains(line, re_array_of_tables)
+            if isfound(re_array_of_tables, line)
                 uuid == where && break
                 uuid = deps = nothing
                 state = :stanza
@@ -533,9 +533,9 @@ function explicit_manifest_deps_get(manifest_file::String, where::UUID, name::St
                     uuid = UUID(m.captures[1])
                 elseif (m = match(re_deps_to_any, line)) != nothing
                     deps = String(m.captures[1])
-                elseif contains(line, re_subsection_deps)
+                elseif isfound(re_subsection_deps, line)
                     state = :deps
-                elseif contains(line, re_section)
+                elseif isfound(re_section, line)
                     state = :other
                 end
             elseif state == :deps && uuid == where
@@ -551,7 +551,7 @@ function explicit_manifest_deps_get(manifest_file::String, where::UUID, name::St
             @warn "Unexpected TOML deps format:\n$deps"
             return nothing
         end
-        contains(deps, repr(name)) || return true
+        isfound(repr(name), deps) || return true
         seekstart(io) # rewind IO handle
         manifest_file_name_uuid(manifest_file, name, io)
     end
diff --git a/base/methodshow.jl b/base/methodshow.jl
index 013246e24c54da..4605ae415445c6 100644
--- a/base/methodshow.jl
+++ b/base/methodshow.jl
@@ -202,7 +202,7 @@ function url(m::Method)
     (m.file == :null || m.file == :string) && return ""
     file = string(m.file)
     line = m.line
-    line <= 0 || contains(file, r"In\[[0-9]+\]") && return ""
+    line <= 0 || isfound(r"In\[[0-9]+\]", file) && return ""
     Sys.iswindows() && (file = replace(file, '\\' => '/'))
     libgit2_id = PkgId(UUID((0x76f85450_5226_5b5a,0x8eaa_529ad045b433)), "LibGit2")
     if inbase(M)
diff --git a/base/mpfr.jl b/base/mpfr.jl
index edb91c90185891..d161df1a750a3c 100644
--- a/base/mpfr.jl
+++ b/base/mpfr.jl
@@ -936,7 +936,7 @@ end
 
 function _prettify_bigfloat(s::String)::String
     mantissa, exponent = split(s, 'e')
-    if !contains(mantissa, '.')
+    if !isfound('.', mantissa)
         mantissa = string(mantissa, '.')
     end
     mantissa = rstrip(mantissa, '0')
diff --git a/base/path.jl b/base/path.jl
index 1bb777dd2377dc..a25d1fde697b2f 100644
--- a/base/path.jl
+++ b/base/path.jl
@@ -78,7 +78,7 @@ end
 
 
 if Sys.iswindows()
-    isabspath(path::String) = contains(path, path_absolute_re)
+    isabspath(path::String) = isfound(path_absolute_re, path)
 else
     isabspath(path::String) = startswith(path, '/')
 end
@@ -113,7 +113,7 @@ julia> isdirpath("/home/")
 true
 ```
 """
-isdirpath(path::String) = contains(splitdrive(path)[2], path_directory_re)
+isdirpath(path::String) = isfound(path_directory_re, splitdrive(path)[2])
 
 """
     splitdir(path::AbstractString) -> (AbstractString, AbstractString)
@@ -218,9 +218,9 @@ function joinpath(a::String, b::String)
     B, b = splitdrive(b)
     !isempty(B) && A != B && return string(B,b)
     C = isempty(B) ? A : B
-    isempty(a)                              ? string(C,b) :
-    contains(a[end:end], path_separator_re) ? string(C,a,b) :
-                                              string(C,a,pathsep(a,b),b)
+    isempty(a)                             ? string(C,b) :
+    isfound(path_separator_re, a[end:end]) ? string(C,a,b) :
+                                             string(C,a,pathsep(a,b),b)
 end
 joinpath(a::AbstractString, b::AbstractString) = joinpath(String(a), String(b))
 
diff --git a/base/regex.jl b/base/regex.jl
index 6f75eee72e5f50..f88192621476b8 100644
--- a/base/regex.jl
+++ b/base/regex.jl
@@ -141,19 +141,19 @@ function getindex(m::RegexMatch, name::Symbol)
 end
 getindex(m::RegexMatch, name::AbstractString) = m[Symbol(name)]
 
-function contains(s::AbstractString, r::Regex, offset::Integer=0)
+function isfound(r::Regex, s::AbstractString; offset::Integer=0)
     compile(r)
     return PCRE.exec(r.regex, String(s), offset, r.match_options,
                      r.match_data)
 end
 
-function contains(s::SubString, r::Regex, offset::Integer=0)
+function isfound(r::Regex, s::SubString; offset::Integer=0)
     compile(r)
     return PCRE.exec(r.regex, s, offset, r.match_options,
                      r.match_data)
 end
 
-(r::Regex)(s) = contains(s, r)
+(r::Regex)(s) = isfound(r, s)
 
 """
     match(r::Regex, s::AbstractString[, idx::Integer[, addopts]])
diff --git a/base/strings/search.jl b/base/strings/search.jl
index 72e434d1f96f68..229dd2f677b00f 100644
--- a/base/strings/search.jl
+++ b/base/strings/search.jl
@@ -425,30 +425,7 @@ julia> findprev("Julia", "JuliaLang", 6)
 """
 findprev(t::AbstractString, s::AbstractString, i::Integer) = _rsearch(s, t, i)
 
-"""
-    contains(haystack::AbstractString, needle::Union{AbstractString,Regex,Char})
-
-Determine whether the second argument is a substring of the first. If `needle`
-is a regular expression, checks whether `haystack` contains a match.
-
-# Examples
-```jldoctest
-julia> contains("JuliaLang is pretty cool!", "Julia")
-true
-
-julia> contains("JuliaLang is pretty cool!", 'a')
-true
-
-julia> contains("aba", r"a.a")
-true
-
-julia> contains("abba", r"a.a")
-false
-```
-"""
-function contains end
-
-contains(haystack::AbstractString, needle::Union{AbstractString,Char}) =
+isfound(needle::Union{AbstractString,Char}, haystack::AbstractString) =
     _searchindex(haystack, needle, firstindex(haystack)) != 0
 
-in(::AbstractString, ::AbstractString) = error("use contains(x,y) for string containment")
+in(::AbstractString, ::AbstractString) = error("use isfound(x, y) for string containment")
diff --git a/base/uuid.jl b/base/uuid.jl
index 533646d59af899..c8f55ad15f480a 100644
--- a/base/uuid.jl
+++ b/base/uuid.jl
@@ -30,7 +30,7 @@ let groupings = [1:8; 10:13; 15:18; 20:23; 25:36]
     function UUID(s::AbstractString)
         s = lowercase(s)
 
-        if !contains(s, r"^[0-9a-f]{8}(?:-[0-9a-f]{4}){3}-[0-9a-f]{12}$")
+        if !isfound(r"^[0-9a-f]{8}(?:-[0-9a-f]{4}){3}-[0-9a-f]{12}$", s)
             throw(ArgumentError("Malformed UUID string: $(repr(s))"))
         end
 
diff --git a/base/version.jl b/base/version.jl
index 37ba3c2297c890..39520d9d0de1f3 100644
--- a/base/version.jl
+++ b/base/version.jl
@@ -21,7 +21,7 @@ struct VersionNumber
             if ident isa Integer
                 ident >= 0 || throw(ArgumentError("invalid negative pre-release identifier: $ident"))
             else
-                if !contains(ident, r"^(?:|[0-9a-z-]*[a-z-][0-9a-z-]*)$"i) ||
+                if !isfound(r"^(?:|[0-9a-z-]*[a-z-][0-9a-z-]*)$"i, ident) ||
                     isempty(ident) && !(length(pre)==1 && isempty(bld))
                     throw(ArgumentError("invalid pre-release identifier: $(repr(ident))"))
                 end
@@ -31,7 +31,7 @@ struct VersionNumber
             if ident isa Integer
                 ident >= 0 || throw(ArgumentError("invalid negative build identifier: $ident"))
             else
-                if !contains(ident, r"^(?:|[0-9a-z-]*[a-z-][0-9a-z-]*)$"i) ||
+                if !isfound(r"^(?:|[0-9a-z-]*[a-z-][0-9a-z-]*)$"i, ident) ||
                     isempty(ident) && length(bld)!=1
                     throw(ArgumentError("invalid build identifier: $(repr(ident))"))
                 end
@@ -83,7 +83,7 @@ function split_idents(s::AbstractString)
     idents = split(s, '.')
     ntuple(length(idents)) do i
         ident = idents[i]
-        contains(ident, r"^\d+$") ? parse(UInt64, ident) : String(ident)
+        isfound(r"^\d+$", ident) ? parse(UInt64, ident) : String(ident)
     end
 end
 
diff --git a/contrib/add_license_to_files.jl b/contrib/add_license_to_files.jl
index 827680ae95f197..eaa1cdf9530ac8 100644
--- a/contrib/add_license_to_files.jl
+++ b/contrib/add_license_to_files.jl
@@ -81,7 +81,7 @@ function check_lines!(
     remove = []
     for i in 1:length(lines)
         line = lines[i]
-        if contains(line, checktxt)
+        if isfound(checktxt, line)
             if strip(line) == strip(prefix * checktxt) || strip(line) == strip(checktxt)
                 push!(remove, i)
             else
diff --git a/contrib/fixup_precompile.jl b/contrib/fixup_precompile.jl
index db47ab149f90ef..4a7103bbdc38a8 100644
--- a/contrib/fixup_precompile.jl
+++ b/contrib/fixup_precompile.jl
@@ -1,5 +1,5 @@
 function needs_USE_GPL_LIBS(s::String)
-    contains(s, "CHOLMOD") && return true
+    isfound("CHOLMOD", s) && return true
     return false
 end
 
@@ -24,7 +24,7 @@ function fixup_precompile(new_precompile_file; merge=false)
         for line in eachline(file)
             line = strip(line)
             # filter out closures, which might have different generated names in different environments
-            contains(line, r"#[0-9]") && continue
+            isfound(r"#[0-9]", line) && continue
             # Other stuff than precompile statements might have been written to STDERR
             startswith(line, "precompile(Tuple{") || continue
             # Ok, add the line
@@ -65,4 +65,4 @@ elseif length(ARGS) == 2
     fixup_precompile(joinpath(pwd(), ARGS[2]); merge = true)
 else
     error("invalid arguments")
-end
\ No newline at end of file
+end
diff --git a/doc/src/base/arrays.md b/doc/src/base/arrays.md
index 11b3c6dbb7b2d0..035f8781b1dbab 100644
--- a/doc/src/base/arrays.md
+++ b/doc/src/base/arrays.md
@@ -129,6 +129,7 @@ Base.findnext(::Any, ::Integer)
 Base.findnext(::Function, ::Any, ::Integer)
 Base.findprev(::Any, ::Integer)
 Base.findprev(::Function, ::Any, ::Integer)
+Base.isfound
 Base.permutedims
 Base.permutedims!
 Base.PermutedDimsArray
diff --git a/doc/src/base/strings.md b/doc/src/base/strings.md
index d71e7ef5b237fd..62b028ce2c123c 100644
--- a/doc/src/base/strings.md
+++ b/doc/src/base/strings.md
@@ -35,7 +35,6 @@ Base.findfirst(::AbstractString, ::AbstractString)
 Base.findnext(::AbstractString, ::AbstractString, ::Integer)
 Base.findlast(::AbstractString, ::AbstractString)
 Base.findprev(::AbstractString, ::AbstractString, ::Integer)
-Base.contains
 Base.reverse(::Union{String,SubString{String}})
 Base.replace(s::AbstractString, ::Pair)
 Base.split
diff --git a/doc/src/manual/strings.md b/doc/src/manual/strings.md
index 50020168e3ccde..f4bcc90dfee884 100644
--- a/doc/src/manual/strings.md
+++ b/doc/src/manual/strings.md
@@ -534,23 +534,23 @@ julia> findnext(equalto('o'), "xylophone", 5)
 julia> findnext(equalto('o'), "xylophone", 8)
 ```
 
-You can use the [`contains`](@ref) function to check if a substring is contained in a string:
+You can use the [`isfound`](@ref) function to check if a substring is found within a string:
 
 ```jldoctest
-julia> contains("Hello, world.", "world")
+julia> isfound("world", "Hello, world.")
 true
 
-julia> contains("Xylophon", "o")
+julia> isfound("o", "Xylophon")
 true
 
-julia> contains("Xylophon", "a")
+julia> isfound("a", "Xylophon")
 false
 
-julia> contains("Xylophon", 'o')
+julia> isfound('o', "Xylophon")
 true
 ```
 
-The last example shows that [`contains`](@ref) can also look for a character literal.
+The last example shows that [`isfound`](@ref) can also look for a character literal.
 
 Two other handy string functions are [`repeat`](@ref) and [`join`](@ref):
 
@@ -605,20 +605,20 @@ julia> typeof(ans)
 Regex
 ```
 
-To check if a regex matches a string, use [`contains`](@ref):
+To check if a regex matches a string, use [`isfound`](@ref):
 
 ```jldoctest
-julia> contains("not a comment", r"^\s*(?:#|$)")
+julia> isfound(r"^\s*(?:#|$)", "not a comment")
 false
 
-julia> contains("# a comment", r"^\s*(?:#|$)")
+julia> isfound(r"^\s*(?:#|$)", "# a comment")
 true
 ```
 
-As one can see here, [`contains`](@ref) simply returns true or false, indicating whether the
-given regex matches the string or not. Commonly, however, one wants to know not just whether a
-string matched, but also *how* it matched. To capture this information about a match, use the
-[`match`](@ref) function instead:
+As one can see here, [`isfound`](@ref) simply returns true or false, indicating whether a
+match for the given regex was found in the string. Commonly, however, one wants to know not
+just whether a string matched, but also *how* it matched. To capture this information about
+a match, use the [`match`](@ref) function instead:
 
 ```jldoctest
 julia> match(r"^\s*(?:#|$)", "not a comment")
diff --git a/stdlib/DelimitedFiles/src/DelimitedFiles.jl b/stdlib/DelimitedFiles/src/DelimitedFiles.jl
index 904ab945669b56..6f58b67d5e48f2 100644
--- a/stdlib/DelimitedFiles/src/DelimitedFiles.jl
+++ b/stdlib/DelimitedFiles/src/DelimitedFiles.jl
@@ -732,7 +732,7 @@ end
 # todo: keyword argument for # of digits to print
 writedlm_cell(io::IO, elt::AbstractFloat, dlm, quotes) = print(io, elt)
 function writedlm_cell(io::IO, elt::AbstractString, dlm::T, quotes::Bool) where T
-    if quotes && !isempty(elt) && (('"' in elt) || ('\n' in elt) || ((T <: Char) ? (dlm in elt) : contains(elt, dlm)))
+    if quotes && !isempty(elt) && (('"' in elt) || ('\n' in elt) || ((T <: Char) ? (dlm in elt) : isfound(dlm, elt)))
         print(io, '"', replace(elt, r"\"" => "\"\""), '"')
     else
         print(io, elt)
diff --git a/stdlib/Distributed/test/distributed_exec.jl b/stdlib/Distributed/test/distributed_exec.jl
index 190e26d36698bc..e855b634b20df6 100644
--- a/stdlib/Distributed/test/distributed_exec.jl
+++ b/stdlib/Distributed/test/distributed_exec.jl
@@ -1301,7 +1301,7 @@ let thrown = false
         thrown = true
         local b = IOBuffer()
         showerror(b, e)
-        @test contains(String(take!(b)), "sqrt will only return")
+        @test isfound("sqrt will only return", String(take!(b)))
     end
     @test thrown
 end
@@ -1375,7 +1375,7 @@ try
     error("unexpected")
 catch ex
     @test isa(ex.captured.ex.exceptions[1].ex, ErrorException)
-    @test contains(ex.captured.ex.exceptions[1].ex.msg, "BoundsError")
+    @test isfound("BoundsError", ex.captured.ex.exceptions[1].ex.msg)
     @test ex.captured.ex.exceptions[2].ex == UndefVarError(:DontExistOn1)
 end
 
diff --git a/stdlib/InteractiveUtils/src/InteractiveUtils.jl b/stdlib/InteractiveUtils/src/InteractiveUtils.jl
index 0c397ba534c8fc..b095c344d9a493 100644
--- a/stdlib/InteractiveUtils/src/InteractiveUtils.jl
+++ b/stdlib/InteractiveUtils/src/InteractiveUtils.jl
@@ -36,7 +36,7 @@ function varinfo(m::Module=Main, pattern::Regex=r"")
                      (value===Base || value===Main || value===Core ? "" : format_bytes(summarysize(value))),
                      summary(value)]
              end
-             for v in sort!(names(m)) if isdefined(m, v) && contains(string(v), pattern) ]
+             for v in sort!(names(m)) if isdefined(m, v) && isfound(pattern, string(v)) ]
 
     pushfirst!(rows, Any["name", "size", "summary"])
 
@@ -106,13 +106,13 @@ function versioninfo(io::IO=stdout; verbose::Bool=false, packages::Bool=false)
 
     println(io, "Environment:")
     for (k,v) in ENV
-        if contains(String(k), r"JULIA")
+        if isfound(r"JULIA", String(k))
             println(io, "  $(k) = $(v)")
         end
     end
     if verbose
         for (k,v) in ENV
-            if contains(String(k), r"PATH|FLAG|^TERM$|HOME")
+            if isfound(r"PATH|FLAG|^TERM$|HOME", String(k))
                 println(io, "  $(k) = $(v)")
             end
         end
diff --git a/stdlib/InteractiveUtils/test/runtests.jl b/stdlib/InteractiveUtils/test/runtests.jl
index 514ffa91eb64f5..53dcad6141be2b 100644
--- a/stdlib/InteractiveUtils/test/runtests.jl
+++ b/stdlib/InteractiveUtils/test/runtests.jl
@@ -31,7 +31,7 @@ function warntype_hastag(f, types, tag)
     iob = IOBuffer()
     code_warntype(iob, f, types)
     str = String(take!(iob))
-    return contains(str, tag)
+    return isfound(tag, str)
 end
 
 pos_stable(x) = x > 0 ? x : zero(x)
@@ -60,7 +60,7 @@ tag = "ANY"
 iob = IOBuffer()
 show(iob, Meta.lower(Main, :(x -> x^2)))
 str = String(take!(iob))
-@test !contains(str, tag)
+@test !isfound(tag, str)
 
 # Make sure non used variables are not emphasized
 has_unused() = (a = rand(5))
@@ -71,7 +71,7 @@ has_unused() = (a = rand(5))
 iob = IOBuffer()
 code_warntype(IOContext(iob, :color => true), x -> (x > 1 ? "foo" : nothing), Tuple{Int64})
 str = String(take!(iob))
-@test contains(str, Base.text_colors[Base.warn_color()])
+@test isfound(Base.text_colors[Base.warn_color()], str)
 
 # Make sure getproperty and setproperty! works with @code_... macros
 struct T1234321
@@ -150,7 +150,7 @@ end
 |:---- | ----:|:------- |
 """
 let v = repr(varinfo(_test_varinfo_))
-    @test contains(v, "| x              |   8 bytes | Float64 |")
+    @test isfound("| x              |   8 bytes | Float64 |", v)
 end
 
 # Issue 14173
@@ -180,9 +180,9 @@ end
             versioninfo(buf, verbose=true)
             ver = read(buf, String)
             @test startswith(ver, "Julia Version $VERSION")
-            @test contains(ver, "Environment:")
-            @test contains(ver, "Package Status:")
-            @test contains(ver, "no packages installed")
+            @test isfound("Environment:", ver)
+            @test isfound("Package Status:", ver)
+            @test isfound("no packages installed", ver)
             @test isempty(readdir(dir))
         end
     end
@@ -296,7 +296,7 @@ end # module ReflectionTest
 
 ix86 = r"i[356]86"
 
-if Sys.ARCH === :x86_64 || contains(string(Sys.ARCH), ix86)
+if Sys.ARCH === :x86_64 || isfound(ix86, string(Sys.ARCH))
     function linear_foo()
         x = 4
         y = 5
@@ -309,18 +309,18 @@ if Sys.ARCH === :x86_64 || contains(string(Sys.ARCH), ix86)
     code_native(buf,linear_foo,(), syntax = :att)
     output=String(take!(buf))
 
-    @test contains(output,rgx)
+    @test isfound(rgx, output)
 
     #test that the code output is intel syntax by checking it has no occurrences of '%'
     code_native(buf,linear_foo,(), syntax = :intel)
     output=String(take!(buf))
 
-    @test !contains(output,rgx)
+    @test !isfound(rgx, output)
 
     code_native(buf,linear_foo,())
     output=String(take!(buf))
 
-    @test contains(output,rgx)
+    @test isfound(rgx, output)
 end
 
 using InteractiveUtils: editor
diff --git a/stdlib/LibGit2/test/libgit2.jl b/stdlib/LibGit2/test/libgit2.jl
index f12cb8cc4d027e..95fe5cc7ddca0a 100644
--- a/stdlib/LibGit2/test/libgit2.jl
+++ b/stdlib/LibGit2/test/libgit2.jl
@@ -812,10 +812,10 @@ mktempdir() do dir
                     # test showing the commit
                     showstr = split(sprint(show, cmt), "\n")
                     # the time of the commit will vary so just test the first two parts
-                    @test contains(showstr[1], "Git Commit:")
-                    @test contains(showstr[2], "Commit Author: Name: TEST, Email: TEST@TEST.COM, Time:")
-                    @test contains(showstr[3], "Committer: Name: TEST, Email: TEST@TEST.COM, Time:")
-                    @test contains(showstr[4], "SHA:")
+                    @test isfound("Git Commit:", showstr[1])
+                    @test isfound("Commit Author: Name: TEST, Email: TEST@TEST.COM, Time:", showstr[2])
+                    @test isfound("Committer: Name: TEST, Email: TEST@TEST.COM, Time:", showstr[3])
+                    @test isfound("SHA:", showstr[4])
                     @test showstr[5] == "Message:"
                     @test showstr[6] == commit_msg1
                     @test LibGit2.revcount(repo, string(commit_oid1), string(commit_oid3)) == (-1,0)
@@ -996,7 +996,7 @@ mktempdir() do dir
                 # test showing a GitBlob
                 blob_show_strs = split(sprint(show, blob), "\n")
                 @test blob_show_strs[1] == "GitBlob:"
-                @test contains(blob_show_strs[2], "Blob id:")
+                @test isfound("Blob id:", blob_show_strs[2])
                 @test blob_show_strs[3] == "Contents are binary."
 
                 blob2 = LibGit2.GitBlob(repo, LibGit2.GitHash(blob))
@@ -1085,9 +1085,9 @@ mktempdir() do dir
                 @test diff_strs[3] == "Number of files: 2"
                 @test diff_strs[4] == "Old file:"
                 @test diff_strs[5] == "DiffFile:"
-                @test contains(diff_strs[6], "Oid:")
-                @test contains(diff_strs[7], "Path:")
-                @test contains(diff_strs[8], "Size:")
+                @test isfound("Oid:", diff_strs[6])
+                @test isfound("Path:", diff_strs[7])
+                @test isfound("Size:", diff_strs[8])
                 @test isempty(diff_strs[9])
                 @test diff_strs[10] == "New file:"
 
diff --git a/stdlib/Libdl/test/runtests.jl b/stdlib/Libdl/test/runtests.jl
index 8a7a7482449619..3c2a26bdd8d972 100644
--- a/stdlib/Libdl/test/runtests.jl
+++ b/stdlib/Libdl/test/runtests.jl
@@ -16,7 +16,7 @@ if !Sys.iswindows() || Sys.windows_version() >= Sys.WINDOWS_VISTA_VER
     end
 end
 @test length(filter(dlls) do dl
-        return contains(basename(dl), Regex("^libjulia(?:.*)\\.$(Libdl.dlext)(?:\\..+)?\$"))
+        return isfound(Regex("^libjulia(?:.*)\\.$(Libdl.dlext)(?:\\..+)?\$"), basename(dl))
     end) == 1 # look for something libjulia-like (but only one)
 
 # library handle pointer must not be NULL
@@ -165,9 +165,9 @@ end
 
 # opening a versioned library that does not exist does not result in adding extension twice
 err = @test_throws ErrorException Libdl.dlopen("./foo.$(Libdl.dlext).0")
-@test !contains(err.value.msg, "foo.$(Libdl.dlext).0.$(Libdl.dlext)")
+@test !isfound("foo.$(Libdl.dlext).0.$(Libdl.dlext)", err.value.msg)
 err = @test_throws ErrorException Libdl.dlopen("./foo.$(Libdl.dlext).0.22.1")
-@test !contains(err.value.msg, "foo.$(Libdl.dlext).0.22.1.$(Libdl.dlext)")
+@test !isfound("foo.$(Libdl.dlext).0.22.1.$(Libdl.dlext)", err.value.msg)
 
 # test dlsym
 let dl = C_NULL
diff --git a/stdlib/LinearAlgebra/src/blas.jl b/stdlib/LinearAlgebra/src/blas.jl
index 5733fa8ad528b3..9414ae00b7cbfc 100644
--- a/stdlib/LinearAlgebra/src/blas.jl
+++ b/stdlib/LinearAlgebra/src/blas.jl
@@ -125,7 +125,7 @@ function check()
     blas = vendor()
     if blas == :openblas || blas == :openblas64
         openblas_config = openblas_get_config()
-        openblas64 = contains(openblas_config, r".*USE64BITINT.*")
+        openblas64 = isfound(r".*USE64BITINT.*", openblas_config)
         if Base.USE_BLAS64 != openblas64
             if !openblas64
                 @error """
diff --git a/stdlib/LinearAlgebra/src/uniformscaling.jl b/stdlib/LinearAlgebra/src/uniformscaling.jl
index a153882f1ed709..aab6c0deb689a5 100644
--- a/stdlib/LinearAlgebra/src/uniformscaling.jl
+++ b/stdlib/LinearAlgebra/src/uniformscaling.jl
@@ -54,7 +54,7 @@ getindex(J::UniformScaling, i::Integer,j::Integer) = ifelse(i==j,J.λ,zero(J.λ)
 
 function show(io::IO, J::UniformScaling)
     s = "$(J.λ)"
-    if contains(s, r"\w+\s*[\+\-]\s*\w+")
+    if isfound(r"\w+\s*[\+\-]\s*\w+", s)
         s = "($s)"
     end
     print(io, "$(typeof(J))\n$s*I")
diff --git a/stdlib/LinearAlgebra/test/triangular.jl b/stdlib/LinearAlgebra/test/triangular.jl
index 284938e1fcd9d3..5fb26e6ae65e1b 100644
--- a/stdlib/LinearAlgebra/test/triangular.jl
+++ b/stdlib/LinearAlgebra/test/triangular.jl
@@ -539,14 +539,14 @@ end
 end
 
 @testset "special printing of Lower/UpperTriangular" begin
-    @test contains(sprint(show, MIME"text/plain"(), LowerTriangular(2ones(Int64,3,3))),
-        r"3×3 (LinearAlgebra\.)?LowerTriangular{Int64,Array{Int64,2}}:\n 2  ⋅  ⋅\n 2  2  ⋅\n 2  2  2")
-    @test contains(sprint(show, MIME"text/plain"(), UnitLowerTriangular(2ones(Int64,3,3))),
-        r"3×3 (LinearAlgebra\.)?UnitLowerTriangular{Int64,Array{Int64,2}}:\n 1  ⋅  ⋅\n 2  1  ⋅\n 2  2  1")
-    @test contains(sprint(show, MIME"text/plain"(), UpperTriangular(2ones(Int64,3,3))),
-        r"3×3 (LinearAlgebra\.)?UpperTriangular{Int64,Array{Int64,2}}:\n 2  2  2\n ⋅  2  2\n ⋅  ⋅  2")
-    @test contains(sprint(show, MIME"text/plain"(), UnitUpperTriangular(2ones(Int64,3,3))),
-        r"3×3 (LinearAlgebra\.)?UnitUpperTriangular{Int64,Array{Int64,2}}:\n 1  2  2\n ⋅  1  2\n ⋅  ⋅  1")
+    @test isfound(r"3×3 (LinearAlgebra\.)?LowerTriangular{Int64,Array{Int64,2}}:\n 2  ⋅  ⋅\n 2  2  ⋅\n 2  2  2",
+                  sprint(show, MIME"text/plain"(), LowerTriangular(2ones(Int64,3,3))))
+    @test isfound(r"3×3 (LinearAlgebra\.)?UnitLowerTriangular{Int64,Array{Int64,2}}:\n 1  ⋅  ⋅\n 2  1  ⋅\n 2  2  1",
+                  sprint(show, MIME"text/plain"(), UnitLowerTriangular(2ones(Int64,3,3))))
+    @test isfound(r"3×3 (LinearAlgebra\.)?UpperTriangular{Int64,Array{Int64,2}}:\n 2  2  2\n ⋅  2  2\n ⋅  ⋅  2",
+                  sprint(show, MIME"text/plain"(), UpperTriangular(2ones(Int64,3,3))))
+    @test isfound(r"3×3 (LinearAlgebra\.)?UnitUpperTriangular{Int64,Array{Int64,2}}:\n 1  2  2\n ⋅  1  2\n ⋅  ⋅  1",
+                  sprint(show, MIME"text/plain"(), UnitUpperTriangular(2ones(Int64,3,3))))
 end
 
 end # module TestTriangular
diff --git a/stdlib/Markdown/src/Common/block.jl b/stdlib/Markdown/src/Common/block.jl
index fd6c9de93d1ac0..ad63d7cea33822 100644
--- a/stdlib/Markdown/src/Common/block.jl
+++ b/stdlib/Markdown/src/Common/block.jl
@@ -211,11 +211,11 @@ function admonition(stream::IO, block::MD)
             let untitled = r"^([a-z]+)$",          # !!! <CATEGORY_NAME>
                 titled   = r"^([a-z]+) \"(.*)\"$", # !!! <CATEGORY_NAME> "<TITLE>"
                 line     = strip(readline(stream))
-                if contains(line, untitled)
+                if isfound(untitled, line)
                     m = match(untitled, line)
                     # When no title is provided we use CATEGORY_NAME, capitalising it.
                     m.captures[1], ucfirst(m.captures[1])
-                elseif contains(line, titled)
+                elseif isfound(titled, line)
                     m = match(titled, line)
                     # To have a blank TITLE provide an explicit empty string as TITLE.
                     m.captures[1], m.captures[2]
@@ -270,12 +270,12 @@ function list(stream::IO, block::MD)
         indent = isempty(bullet) ? (return false) : length(bullet)
         # Calculate the starting number and regex to use for bullet matching.
         initial, regex =
-            if contains(bullet, BULLETS)
+            if isfound(BULLETS, bullet)
                 # An unordered list. Use `-1` to flag the list as unordered.
                 -1, BULLETS
-            elseif contains(bullet, r"^ {0,3}\d+(\.|\))( |$)")
+            elseif isfound(r"^ {0,3}\d+(\.|\))( |$)", bullet)
                 # An ordered list. Either with `1. ` or `1) ` style numbering.
-                r = contains(bullet, ".") ? r"^ {0,3}(\d+)\.( |$)" : r"^ {0,3}(\d+)\)( |$)"
+                r = isfound(".", bullet) ? r"^ {0,3}(\d+)\.( |$)" : r"^ {0,3}(\d+)\)( |$)"
                 Base.parse(Int, match(r, bullet).captures[1]), r
             else
                 # Failed to match any bullets. This branch shouldn't actually be needed
diff --git a/stdlib/Markdown/src/Common/inline.jl b/stdlib/Markdown/src/Common/inline.jl
index 63a5fb887c7fa4..b2399e255ba787 100644
--- a/stdlib/Markdown/src/Common/inline.jl
+++ b/stdlib/Markdown/src/Common/inline.jl
@@ -152,7 +152,7 @@ function _is_mailto(s::AbstractString)
     length(s) < 6 && return false
     # slicing strings is a bit risky, but this equality check is safe
     lowercase(s[1:6]) == "mailto:" || return false
-    return contains(s[6:end], _email_regex)
+    return isfound(_email_regex, s[6:end])
 end
 
 # –––––––––––
diff --git a/stdlib/Markdown/src/render/plain.jl b/stdlib/Markdown/src/render/plain.jl
index dbee4dcf33fa68..5d2619e292b88e 100644
--- a/stdlib/Markdown/src/render/plain.jl
+++ b/stdlib/Markdown/src/render/plain.jl
@@ -120,7 +120,7 @@ plaininline(io::IO, md::Bold) = plaininline(io, "**", md.text, "**")
 plaininline(io::IO, md::Italic) = plaininline(io, "*", md.text, "*")
 
 function plaininline(io::IO, md::Code)
-    if contains(md.code, "`")
+    if isfound("`", md.code)
         n = maximum(length(m.match) for m in eachmatch(r"(`+)", md.code))
         s = "`"^((iseven(n) ? 1 : 2) + n)
         print(io, s, Base.startswith(md.code, "`") ? " " : "")
diff --git a/stdlib/Markdown/src/render/rst.jl b/stdlib/Markdown/src/render/rst.jl
index 737cf316c88516..44f1bc5eae5670 100644
--- a/stdlib/Markdown/src/render/rst.jl
+++ b/stdlib/Markdown/src/render/rst.jl
@@ -115,7 +115,7 @@ rstinline(io::IO, md::Vector) = !isempty(md) && rstinline(io, md...)
 # rstinline(io::IO, md::Image) = rstinline(io, ".. image:: ", md.url)
 
 function rstinline(io::IO, md::Link)
-    if contains(md.url, r":(func|obj|ref|exc|class|const|data):`\.*")
+    if isfound(r":(func|obj|ref|exc|class|const|data):`\.*", md.url)
         rstinline(io, md.url)
     else
         rstinline(io, "`", md.text, " <", md.url, ">`_")
diff --git a/stdlib/Markdown/src/render/terminal/formatting.jl b/stdlib/Markdown/src/render/terminal/formatting.jl
index 866fd7e6257299..d9e5ff1e2bceb0 100644
--- a/stdlib/Markdown/src/render/terminal/formatting.jl
+++ b/stdlib/Markdown/src/render/terminal/formatting.jl
@@ -11,7 +11,7 @@ lines(s) = split(s, "\n")
 
 # This could really be more efficient
 function wrapped_lines(io::IO, s::AbstractString; width = 80, i = 0)
-    if contains(s, r"\n")
+    if isfound(r"\n", s)
         return vcat(map(s->wrapped_lines(io, s, width = width, i = i), split(s, "\n"))...)
     end
     ws = words(s)
diff --git a/stdlib/Markdown/test/runtests.jl b/stdlib/Markdown/test/runtests.jl
index 8512b54324f773..b24076e4bacbe8 100644
--- a/stdlib/Markdown/test/runtests.jl
+++ b/stdlib/Markdown/test/runtests.jl
@@ -144,16 +144,16 @@ let text =
         @test Markdown.rst(md) == expected
     end
     let html = Markdown.html(md)
-        @test contains(html, ",<a href=\"#footnote-1\" class=\"footnote\">[1]</a>")
-        @test contains(html, ".<a href=\"#footnote-note\" class=\"footnote\">[note]</a>")
-        @test contains(html, "<div class=\"footnote\" id=\"footnote-1\"><p class=\"footnote-title\">1</p>")
-        @test contains(html, "<div class=\"footnote\" id=\"footnote-note\"><p class=\"footnote-title\">note</p>")
+        @test isfound(",<a href=\"#footnote-1\" class=\"footnote\">[1]</a>", html)
+        @test isfound(".<a href=\"#footnote-note\" class=\"footnote\">[note]</a>", html)
+        @test isfound("<div class=\"footnote\" id=\"footnote-1\"><p class=\"footnote-title\">1</p>", html)
+        @test isfound("<div class=\"footnote\" id=\"footnote-note\"><p class=\"footnote-title\">note</p>", html)
     end
     let latex = Markdown.latex(md)
-        @test contains(latex, ",\\footnotemark[1]")
-        @test contains(latex, ".\\footnotemark[note]")
-        @test contains(latex, "\n\\footnotetext[1]{Footnote text for")
-        @test contains(latex, "\n\\footnotetext[note]{A longer footnote:\n")
+        @test isfound(",\\footnotemark[1]", latex)
+        @test isfound(".\\footnotemark[note]", latex)
+        @test isfound("\n\\footnotetext[1]{Footnote text for", latex)
+        @test isfound("\n\\footnotetext[note]{A longer footnote:\n", latex)
     end
 end
 
@@ -239,9 +239,9 @@ let doc = Markdown.parse(
         3. b
         """
     )
-    @test contains(sprint(term, doc), "1. ")
-    @test contains(sprint(term, doc), "2. ")
-    @test !contains(sprint(term, doc), "3. ")
+    @test isfound("1. ", sprint(term, doc))
+    @test isfound("2. ", sprint(term, doc))
+    @test !isfound("3. ", sprint(term, doc))
 end
 
 # HTML output
diff --git a/stdlib/Pkg/src/read.jl b/stdlib/Pkg/src/read.jl
index f1698b1553a09c..1d5e9bc4362041 100644
--- a/stdlib/Pkg/src/read.jl
+++ b/stdlib/Pkg/src/read.jl
@@ -20,7 +20,7 @@ function available(names=readdir("METADATA"))
         versdir = joinpath("METADATA", pkg, "versions")
         isdir(versdir) || continue
         for ver in readdir(versdir)
-            contains(ver, Base.VERSION_REGEX) || continue
+            isfound(Base.VERSION_REGEX, ver) || continue
             isfile(versdir, ver, "sha1") || continue
             haskey(pkgs,pkg) || (pkgs[pkg] = Dict{VersionNumber,Available}())
             pkgs[pkg][VersionNumber(ver)] = Available(
@@ -41,7 +41,7 @@ function latest(names=readdir("METADATA"))
         isdir(versdir) || continue
         pkgversions = VersionNumber[]
         for ver in readdir(versdir)
-            contains(ver, Base.VERSION_REGEX) || continue
+            isfound(Base.VERSION_REGEX, ver) || continue
             isfile(versdir, ver, "sha1") || continue
             push!(pkgversions, VersionNumber(ver))
         end
@@ -116,7 +116,7 @@ function ispinned(prepo::LibGit2.GitRepo)
     LibGit2.isattached(prepo) || return false
     br = LibGit2.branch(prepo)
     # note: regex is based on the naming scheme used in Entry.pin()
-    return contains(br, r"^pinned\.[0-9a-f]{8}\.tmp$")
+    return isfound(r"^pinned\.[0-9a-f]{8}\.tmp$", br)
 end
 
 function installed_version(pkg::AbstractString, prepo::LibGit2.GitRepo, avail::Dict=available(pkg))
diff --git a/stdlib/Pkg/src/reqs.jl b/stdlib/Pkg/src/reqs.jl
index 300ed8d90aeb80..6c5d63d17687e2 100644
--- a/stdlib/Pkg/src/reqs.jl
+++ b/stdlib/Pkg/src/reqs.jl
@@ -27,7 +27,7 @@ struct Requirement <: Line
         end
         isempty(fields) && throw(PkgError("invalid requires entry: $content"))
         package = popfirst!(fields)
-        all(field->contains(field, Base.VERSION_REGEX), fields) ||
+        all(field->isfound(Base.VERSION_REGEX, field), fields) ||
             throw(PkgError("invalid requires entry for $package: $content"))
         versions = map(VersionNumber, fields)
         issorted(versions) || throw(PkgError("invalid requires entry for $package: $content"))
@@ -59,7 +59,7 @@ function read(readable::Vector{<:AbstractString})
     lines = Line[]
     for line in readable
         line = chomp(line)
-        push!(lines, contains(line, r"^\s*(?:#|$)") ? Comment(line) : Requirement(line))
+        push!(lines, isfound(r"^\s*(?:#|$)", line) ? Comment(line) : Requirement(line))
     end
     return lines
 end
@@ -67,7 +67,7 @@ end
 function read(readable::Union{IO,Base.AbstractCmd})
     lines = Line[]
     for line in eachline(readable)
-        push!(lines, contains(line, r"^\s*(?:#|$)") ? Comment(line) : Requirement(line))
+        push!(lines, isfound(r"^\s*(?:#|$)", line) ? Comment(line) : Requirement(line))
     end
     return lines
 end
diff --git a/stdlib/Pkg/test/pkg.jl b/stdlib/Pkg/test/pkg.jl
index c033d0fae4d6ff..06cf2b7f38851f 100644
--- a/stdlib/Pkg/test/pkg.jl
+++ b/stdlib/Pkg/test/pkg.jl
@@ -87,7 +87,7 @@ temp_pkg_dir() do
                 end
             end
             @test isa(ex,Pkg.PkgError)
-            @test contains(ex.msg, "Cannot clone Example from notarealprotocol://github.com/JuliaLang/Example.jl.git")
+            @test isfound("Cannot clone Example from notarealprotocol://github.com/JuliaLang/Example.jl.git", ex.msg)
         end
     end
 
@@ -415,16 +415,16 @@ temp_pkg_dir() do
         # Pkg.build works without the src directory now
         # but it's probably fine to require it.
         msg = read(`$(Base.julia_cmd()) --startup-file=no -e 'redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); import Pkg; Pkg.build("BuildFail")'`, String)
-        @test contains(msg, "Building BuildFail")
-        @test !contains(msg, "Build failed for BuildFail")
+        @test isfound("Building BuildFail", msg)
+        @test !isfound("Build failed for BuildFail", msg)
         open(depsbuild, "w") do fd
             println(fd, "error(\"Throw build error\")")
         end
         msg = read(`$(Base.julia_cmd()) --startup-file=no -e 'redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); import Pkg; Pkg.build("BuildFail")'`, String)
-        @test contains(msg, "Building BuildFail")
-        @test contains(msg, "Build failed for BuildFail")
-        @test contains(msg, "Pkg.build(\"BuildFail\")")
-        @test contains(msg, "Throw build error")
+        @test isfound("Building BuildFail", msg)
+        @test isfound("Build failed for BuildFail", msg)
+        @test isfound("Pkg.build(\"BuildFail\")", msg)
+        @test isfound("Throw build error", msg)
     end
 
     # issue #15948
@@ -432,8 +432,8 @@ temp_pkg_dir() do
         Pkg.rm(package)  # Remove package if installed
         @test Pkg.installed(package) === nothing  # Registered with METADATA but not installed
         msg = read(ignorestatus(`$(Base.julia_cmd()) --startup-file=no -e "redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); import Pkg; Pkg.build(\"$package\")"`), String)
-        @test contains(msg, "$package is not an installed package")
-        @test !contains(msg, "signal (15)")
+        @test isfound("$package is not an installed package", msg)
+        @test !isfound("signal (15)", msg)
     end
 
     # issue #20695
@@ -506,7 +506,7 @@ temp_pkg_dir() do
             Pkg.add("Iterators")
             Pkg.update("Iterators")
         end
-        @test all(!contains(l.message,"updated but were already imported") for l in logs)
+        @test all(!isfound("updated but were already imported", l.message) for l in logs)
 
         # Do it again, because the above Iterators test will update things prematurely
         LibGit2.with(LibGit2.GitRepo, metadata_dir) do repo
@@ -522,9 +522,9 @@ temp_pkg_dir() do
         logs,_ = Test.collect_test_logs() do
             Pkg.update("ColorTypes")
         end
-        @test any(contains(l, (:info,r"Upgrading ColorTypes: v0\.2\.2 => v\d+\.\d+\.\d+")) for l in logs)
-        @test any(contains(l, (:info,r"Upgrading Compat: v0\.7\.18 => v\d+\.\d+\.\d+")) for l in logs)
-        @test !any(contains(l, (:info,r"Upgrading Colors")) for l in logs)
+        @test any(isfound((:info, r"Upgrading ColorTypes: v0\.2\.2 => v\d+\.\d+\.\d+"), l) for l in logs)
+        @test any(isfound((:info, r"Upgrading Compat: v0\.7\.18 => v\d+\.\d+\.\d+"), l) for l in logs)
+        @test !any(isfound((:info, r"Upgrading Colors"), l) for l in logs)
 
         @test Pkg.installed("Colors") == v"0.6.4"
 
@@ -547,7 +547,7 @@ temp_pkg_dir() do
         Pkg.add(package)
         msg = read(ignorestatus(`$(Base.julia_cmd()) --startup-file=no -e
             "redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); using Example; import Pkg; Pkg.update(\"$package\")"`), String)
-        @test contains(msg, Regex("- $package.*Restart Julia to use the updated versions","s"))
+        @test isfound(Regex("- $package.*Restart Julia to use the updated versions","s"), msg)
     end
 
     # Verify that the --startup-file flag is respected by Pkg.build / Pkg.test
@@ -572,24 +572,24 @@ temp_pkg_dir() do
         withenv((Sys.iswindows() ? "USERPROFILE" : "HOME") => home) do
             code = "redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); import Pkg; Pkg.build(\"$package\")"
             msg = read(`$(Base.julia_cmd()) --startup-file=no -e $code`, String)
-            @test contains(msg, "JULIA_RC_LOADED defined false")
-            @test contains(msg, "Main.JULIA_RC_LOADED defined false")
+            @test isfound("JULIA_RC_LOADED defined false", msg)
+            @test isfound("Main.JULIA_RC_LOADED defined false", msg)
 
             msg = read(`$(Base.julia_cmd()) --startup-file=yes -e $code`, String)
-            @test contains(msg, "JULIA_RC_LOADED defined false")
-            @test contains(msg, "Main.JULIA_RC_LOADED defined true")
+            @test isfound("JULIA_RC_LOADED defined false", msg)
+            @test isfound("Main.JULIA_RC_LOADED defined true", msg)
 
             code = "redirect_stderr(stdout); using Logging; global_logger(SimpleLogger(stdout)); import Pkg; Pkg.test(\"$package\")"
 
             msg = read(`$(Base.julia_cmd()) --startup-file=no -e $code`, String)
-            @test contains(msg, "JULIA_RC_LOADED defined false")
-            @test contains(msg, "Main.JULIA_RC_LOADED defined false")
+            @test isfound("JULIA_RC_LOADED defined false", msg)
+            @test isfound("Main.JULIA_RC_LOADED defined false", msg)
 
             # Note: Since both the startup-file and "runtests.jl" are run in the Main
             # module any global variables created in the startup file can be referenced.
             msg = read(`$(Base.julia_cmd()) --startup-file=yes -e $code`, String)
-            @test contains(msg, "JULIA_RC_LOADED defined true")
-            @test contains(msg, "Main.JULIA_RC_LOADED defined true")
+            @test isfound("JULIA_RC_LOADED defined true", msg)
+            @test isfound("Main.JULIA_RC_LOADED defined true", msg)
         end
     end
 
@@ -660,7 +660,7 @@ end
 
 let io = IOBuffer()
     Base.showerror(io, Pkg.Entry.PkgTestError("ppp"), backtrace())
-    @test !contains(String(take!(io)), "backtrace()")
+    @test !isfound("backtrace()", String(take!(io)))
 end
 
 @testset "Relative path operations" begin
diff --git a/stdlib/Pkg3/bin/utils.jl b/stdlib/Pkg3/bin/utils.jl
index 4a84f6af96a13e..8d9d14295eab35 100644
--- a/stdlib/Pkg3/bin/utils.jl
+++ b/stdlib/Pkg3/bin/utils.jl
@@ -114,5 +114,5 @@ function write_toml(f::Function, names::String...)
     end
 end
 
-toml_key(str::String) = contains(str, r"[^\w-]") ? repr(str) : str
+toml_key(str::String) = isfound(r"[^\w-]", str) ? repr(str) : str
 toml_key(strs::String...) = join(map(toml_key, [strs...]), '.')
diff --git a/stdlib/Pkg3/src/Operations.jl b/stdlib/Pkg3/src/Operations.jl
index c1e71492ecb15d..3bebbd81b2fb0d 100644
--- a/stdlib/Pkg3/src/Operations.jl
+++ b/stdlib/Pkg3/src/Operations.jl
@@ -494,7 +494,7 @@ function find_stdlib_deps(ctx::Context, path::String)
             endswith(file, ".jl") || continue
             filecontent = read(joinpath(root, file), String)
             for ((uuid, stdlib), r) in zip(ctx.stdlibs, regexps)
-                if contains(filecontent, r)
+                if isfound(r, filecontent)
                     stdlib_deps[uuid] = stdlib
                 end
             end
diff --git a/stdlib/Pkg3/src/Pkg2/reqs.jl b/stdlib/Pkg3/src/Pkg2/reqs.jl
index 2af7083a8c84b1..1b65073f6dfaf3 100644
--- a/stdlib/Pkg3/src/Pkg2/reqs.jl
+++ b/stdlib/Pkg3/src/Pkg2/reqs.jl
@@ -25,7 +25,7 @@ struct Requirement <: Line
         end
         isempty(fields) && throw(PkgError("invalid requires entry: $content"))
         package = popfirst!(fields)
-        all(field->contains(field, Base.VERSION_REGEX), fields) ||
+        all(field->isfound(Base.VERSION_REGEX, field), fields) ||
             throw(PkgError("invalid requires entry for $package: $content"))
         versions = VersionNumber.(fields)
         issorted(versions) || throw(PkgError("invalid requires entry for $package: $content"))
@@ -36,11 +36,11 @@ end
 function read(readable::Union{IO,Base.AbstractCmd})
     lines = Line[]
     for line in eachline(readable)
-        push!(lines, contains(line, r"^\s*(?:#|$)") ? Comment(line) : Requirement(line))
+        push!(lines, isfound(r"^\s*(?:#|$)", line) ? Comment(line) : Requirement(line))
     end
     return lines
 end
 read(file::AbstractString) = isfile(file) ? open(read,file) : Line[]
 
 
-end # module
\ No newline at end of file
+end # module
diff --git a/stdlib/Pkg3/src/PlatformEngines.jl b/stdlib/Pkg3/src/PlatformEngines.jl
index 5a936f86d090fb..66a03d1878cb4d 100644
--- a/stdlib/Pkg3/src/PlatformEngines.jl
+++ b/stdlib/Pkg3/src/PlatformEngines.jl
@@ -363,7 +363,7 @@ function parse_7z_list(output::AbstractString)
 
     # Find index of " Name". (can't use `findfirst(generator)` until this is
     # closed: https://github.com/JuliaLang/julia/issues/16884
-    header_row = find(contains(l, " Name") && contains(l, " Attr") for l in lines)[1]
+    header_row = find(isfound(" Name", l) && isfound(" Attr", l) for l in lines)[1]
     name_idx = search(lines[header_row], "Name")[1]
     attr_idx = search(lines[header_row], "Attr")[1] - 1
 
diff --git a/stdlib/Pkg3/src/REPLMode.jl b/stdlib/Pkg3/src/REPLMode.jl
index a7a21bc8c346e3..a97d1113f3c8c2 100644
--- a/stdlib/Pkg3/src/REPLMode.jl
+++ b/stdlib/Pkg3/src/REPLMode.jl
@@ -131,11 +131,11 @@ let uuid = raw"(?i)[0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12}(
 end
 
 function parse_package(word::AbstractString)::PackageSpec
-    if contains(word, uuid_re)
+    if isfound(uuid_re, word)
         return PackageSpec(UUID(word))
-    elseif contains(word, name_re)
+    elseif isfound(name_re, word)
         return PackageSpec(String(match(name_re, word).captures[1]))
-    elseif contains(word, name_uuid_re)
+    elseif isfound(name_uuid_re, word)
         m = match(name_uuid_re, word)
         return PackageSpec(String(m.captures[1]), UUID(m.captures[2]))
     else
diff --git a/stdlib/Pkg3/src/Types.jl b/stdlib/Pkg3/src/Types.jl
index 867569932a6bad..f796c32dd378d5 100644
--- a/stdlib/Pkg3/src/Types.jl
+++ b/stdlib/Pkg3/src/Types.jl
@@ -762,11 +762,11 @@ function find_registered!(
         open(joinpath(registry, "Registry.toml")) do io
             # skip forward until [packages] section
             for line in eachline(io)
-                contains(line, r"^ \s* \[ \s* packages \s* \] \s* $"x) && break
+                isfound(r"^ \s* \[ \s* packages \s* \] \s* $"x, line) && break
             end
             # find lines with uuid or name we're looking for
             for line in eachline(io)
-                contains(line,regex) || continue
+                isfound(regex, line) || continue
                 m = match(line_re, line)
                 m == nothing &&
                     error("misformatted registry.toml package entry: $line")
diff --git a/stdlib/Pkg3/test/pkg.jl b/stdlib/Pkg3/test/pkg.jl
index b3be6fbdb69699..d6e72975cf804f 100644
--- a/stdlib/Pkg3/test/pkg.jl
+++ b/stdlib/Pkg3/test/pkg.jl
@@ -147,7 +147,7 @@ temp_pkg_dir() do project_path
         try
             Pkg3.add([PackageSpec(TEST_PKG.name, VersionSpec(v"55"))])
         catch e
-            @test contains(sprint(showerror, e), TEST_PKG.name)
+            @test isfound(TEST_PKG.name, sprint(showerror, e))
         end
     end
 
diff --git a/stdlib/REPL/src/REPLCompletions.jl b/stdlib/REPL/src/REPLCompletions.jl
index b2247f30d69694..0f9aec21e52e9d 100644
--- a/stdlib/REPL/src/REPLCompletions.jl
+++ b/stdlib/REPL/src/REPLCompletions.jl
@@ -126,7 +126,7 @@ function complete_keyword(s::Union{String,SubString{String}})
 end
 
 function complete_path(path::AbstractString, pos; use_envpath=false)
-    if Base.Sys.isunix() && contains(path, r"^~(?:/|$)")
+    if Base.Sys.isunix() && isfound(r"^~(?:/|$)", path)
         # if the path is just "~", don't consider the expanded username as a prefix
         if path == "~"
             dir, prefix = homedir(), ""
@@ -419,7 +419,7 @@ function afterusing(string::String, startpos::Int)
     r = findfirst(r"\s(gnisu|tropmi)\b", rstr)
     isempty(r) && return false
     fr = reverseind(str, last(r))
-    return contains(str[fr:end], r"^\b(using|import)\s*((\w+[.])*\w+\s*,\s*)*$")
+    return isfound(r"^\b(using|import)\s*((\w+[.])*\w+\s*,\s*)*$", str[fr:end])
 end
 
 function bslash_completions(string, pos)
diff --git a/stdlib/REPL/src/docview.jl b/stdlib/REPL/src/docview.jl
index 22edebcd79592f..59ad9daa524306 100644
--- a/stdlib/REPL/src/docview.jl
+++ b/stdlib/REPL/src/docview.jl
@@ -479,7 +479,7 @@ const builtins = ["abstract type", "baremodule", "begin", "break",
 
 moduleusings(mod) = ccall(:jl_module_usings, Any, (Any,), mod)
 
-filtervalid(names) = filter(x->!contains(x, r"#"), map(string, names))
+filtervalid(names) = filter(x->!isfound(r"#", x), map(string, names))
 
 accessible(mod::Module) =
     [filter!(s -> !Base.isdeprecated(mod, s), names(mod, all = true, imported = true));
diff --git a/stdlib/REPL/src/latex_symbols.jl b/stdlib/REPL/src/latex_symbols.jl
index 339b30496d81ba..96f44381ae7095 100644
--- a/stdlib/REPL/src/latex_symbols.jl
+++ b/stdlib/REPL/src/latex_symbols.jl
@@ -25,7 +25,7 @@ for c in child_nodes(root(xdoc))
             id = attribute(ce, "id")
             U = string(map(s -> Char(parse(Int, s, base = 16)),
                            split(id[2:end], "-"))...)
-            if contains(L, r"^\\[A-Za-z]+$") && !isa(U,String)
+            if isfound(r"^\\[A-Za-z]+$", L) && !isa(U,String)
                 if L in Ls
                     println("# duplicated symbol $L ($id)")
                 else
diff --git a/stdlib/REPL/test/repl.jl b/stdlib/REPL/test/repl.jl
index 01383edde18054..ee876d362de159 100644
--- a/stdlib/REPL/test/repl.jl
+++ b/stdlib/REPL/test/repl.jl
@@ -119,8 +119,8 @@ fake_repl() do stdin_write, stdout_read, repl
     #    readuntil(stdout_read, "shell> ")
     #    write(stdin_write, "echo hello >/dev/null\n")
     #    let s = readuntil(stdout_read, "\n", keep=true)
-    #        @test contains(s, "shell> ") # make sure we echoed the prompt
-    #        @test contains(s, "echo hello >/dev/null") # make sure we echoed the input
+    #        @test isfound("shell> ", s) # make sure we echoed the prompt
+    #        @test isfound("echo hello >/dev/null", s) # make sure we echoed the input
     #    end
     #    @test readuntil(stdout_read, "\n", keep=true) == "\e[0m\n"
     #end
@@ -131,8 +131,8 @@ fake_repl() do stdin_write, stdout_read, repl
         readuntil(stdout_read, "shell> ")
         write(stdin_write, "'\n") # invalid input
         s = readuntil(stdout_read, "\n")
-        @test contains(s, "shell> ") # check for the echo of the prompt
-        @test contains(s, "'") # check for the echo of the input
+        @test isfound("shell> ", s) # check for the echo of the prompt
+        @test isfound("'", s) # check for the echo of the input
         s = readuntil(stdout_read, "\n\n")
         @test startswith(s, "\e[0mERROR: unterminated single quote\nStacktrace:\n [1] ") ||
               startswith(s, "\e[0m\e[1m\e[91mERROR: \e[39m\e[22m\e[91munterminated single quote\e[39m\nStacktrace:\n [1] ")
@@ -146,8 +146,8 @@ fake_repl() do stdin_write, stdout_read, repl
     #        readuntil(stdout_read, "shell> ")
     #        write(stdin_write, "echo \$123 >$tmp\n")
     #        let s = readuntil(stdout_read, "\n")
-    #            @test contains(s, "shell> ") # make sure we echoed the prompt
-    #            @test contains(s, "echo \$123 >$tmp") # make sure we echoed the input
+    #            @test isfound("shell> ", s) # make sure we echoed the prompt
+    #            @test isfound("echo \$123 >$tmp", s) # make sure we echoed the input
     #        end
     #        @test readuntil(stdout_read, "\n", keep=true) == "\e[0m\n"
     #        @test read(tmp, String) == "123\n"
@@ -173,11 +173,11 @@ fake_repl() do stdin_write, stdout_read, repl
                 # if shell width is precisely the text width,
                 # we may print some extra characters to fix the cursor state
                 s = readuntil(stdout_read, "\n", keep=true)
-                @test contains(s, "shell> ")
+                @test isfound("shell> ", s)
                 s = readuntil(stdout_read, "\n", keep=true)
                 @test s == "\r\r\n"
             else
-                @test contains(s, "shell> ")
+                @test isfound("shell> ", s)
             end
             s = readuntil(stdout_read, "\n", keep=true)
             @test s == "\e[0m\n" # the child has exited
@@ -193,7 +193,7 @@ fake_repl() do stdin_write, stdout_read, repl
     let
         write(stdin_write, "\0\n")
         s = readuntil(stdout_read, "\n\n")
-        @test !contains(s, "invalid character")
+        @test !isfound("invalid character", s)
     end
 
     # Test that accepting a REPL result immediately shows up, not
@@ -699,7 +699,7 @@ function test19864()
     REPL.print_response(buf, Error19864(), [], false, false, nothing)
     return String(take!(buf))
 end
-@test contains(test19864(), "correct19864")
+@test isfound("correct19864", test19864())
 
 # Test containers in error messages are limited #18726
 let io = IOBuffer()
@@ -837,28 +837,27 @@ for keys = [altkeys, merge(altkeys...)],
 
             # Check that the correct prompt was displayed
             output = readuntil(stdout_read, "1 * 1;", keep=true)
-            @test !contains(LineEdit.prompt_string(altprompt), output)
-            @test !contains("julia> ", output)
+            @test !isfound(output, LineEdit.prompt_string(altprompt))
+            @test !isfound(output, "julia> ")
 
             # Check the history file
             history = read(histfile, String)
-            @test contains(history,
-                           r"""
-                           ^\#\ time:\ .*\n
-                            \#\ mode:\ julia\n
-                            \t1\ \+\ 1;\n
-                            \#\ time:\ .*\n
-                            \#\ mode:\ julia\n
-                            \tmulti=2;\n
-                            \tline=2;\n
-                            \#\ time:\ .*\n
-                            \#\ mode:\ julia\n
-                            \tmulti=3;\n
-                            \tline=1;\n
-                            \#\ time:\ .*\n
-                            \#\ mode:\ julia\n
-                            \t1\ \*\ 1;\n$
-                           """xm)
+            @test isfound(r"""
+                          ^\#\ time:\ .*\n
+                           \#\ mode:\ julia\n
+                           \t1\ \+\ 1;\n
+                           \#\ time:\ .*\n
+                           \#\ mode:\ julia\n
+                           \tmulti=2;\n
+                           \tline=2;\n
+                           \#\ time:\ .*\n
+                           \#\ mode:\ julia\n
+                           \tmulti=3;\n
+                           \tline=1;\n
+                           \#\ time:\ .*\n
+                           \#\ mode:\ julia\n
+                           \t1\ \*\ 1;\n$
+                          """xm, history)
         end
     finally
         rm(histfile, force=true)
diff --git a/stdlib/REPL/test/replcompletions.jl b/stdlib/REPL/test/replcompletions.jl
index d780ea2d47624a..a2b80e814eca8a 100644
--- a/stdlib/REPL/test/replcompletions.jl
+++ b/stdlib/REPL/test/replcompletions.jl
@@ -440,7 +440,7 @@ let s = "CompletionFoo.kwtest( "
     c, r, res = test_complete(s)
     @test !res
     @test length(c) == 1
-    @test contains(c[1], "x, y, w...")
+    @test isfound("x, y, w...", c[1])
 end
 
 # Test of inference based getfield completion
diff --git a/stdlib/Serialization/test/runtests.jl b/stdlib/Serialization/test/runtests.jl
index 0a3e66dadf0dbc..591079b87ac0cd 100644
--- a/stdlib/Serialization/test/runtests.jl
+++ b/stdlib/Serialization/test/runtests.jl
@@ -442,8 +442,8 @@ using .Shell, .Instance1
 io = IOBuffer()
 serialize(io, foo)
 str = String(take!(io))
-@test !contains(str, "Instance1")
-@test contains(str, "Shell")
+@test !isfound("Instance1", str)
+@test isfound("Shell", str)
 
 end  # module Test13452
 
diff --git a/stdlib/SparseArrays/test/sparsevector.jl b/stdlib/SparseArrays/test/sparsevector.jl
index 268263191cb78e..79eff93e09a380 100644
--- a/stdlib/SparseArrays/test/sparsevector.jl
+++ b/stdlib/SparseArrays/test/sparsevector.jl
@@ -41,9 +41,9 @@ end
     end
 end
 @testset "show" begin
-    @test contains(string(spv_x1), "1.25")
-    @test contains(string(spv_x1), "-0.75")
-    @test contains(string(spv_x1), "3.5")
+    @test isfound("1.25", string(spv_x1))
+    @test isfound("-0.75", string(spv_x1))
+    @test isfound("3.5", string(spv_x1))
 end
 
 ### Comparison helper to ensure exact equality with internal structure
diff --git a/stdlib/SuiteSparse/test/cholmod.jl b/stdlib/SuiteSparse/test/cholmod.jl
index 08afc74660832c..01c962af78b9bd 100644
--- a/stdlib/SuiteSparse/test/cholmod.jl
+++ b/stdlib/SuiteSparse/test/cholmod.jl
@@ -631,8 +631,8 @@ GC.gc()
 @testset "Issue 11747 - Wrong show method defined for FactorComponent" begin
     v = cholfact(sparse(Float64[ 10 1 1 1; 1 10 0 0; 1 0 10 0; 1 0 0 10])).L
     for s in (sprint(show, MIME("text/plain"), v), sprint(show, v))
-        @test contains(s, "method:  simplicial")
-        @test !contains(s, "#undef")
+        @test isfound("method:  simplicial", s)
+        @test !isfound("#undef", s)
     end
 end
 
diff --git a/stdlib/Test/src/Test.jl b/stdlib/Test/src/Test.jl
index bdffcc68808a35..55549bf8e74003 100644
--- a/stdlib/Test/src/Test.jl
+++ b/stdlib/Test/src/Test.jl
@@ -533,8 +533,8 @@ end
 
 # Test for warning messages (deprecated)
 
-contains_warn(output, s::AbstractString) = contains(output, s)
-contains_warn(output, s::Regex) = contains(output, s)
+contains_warn(output, s::AbstractString) = isfound(s, output)
+contains_warn(output, s::Regex) = isfound(s, output)
 contains_warn(output, s::Function) = s(output)
 contains_warn(output, S::Union{AbstractArray,Tuple}) = all(s -> contains_warn(output, s), S)
 
diff --git a/stdlib/Test/src/logging.jl b/stdlib/Test/src/logging.jl
index b02bdadcd481c4..51ef840e33b135 100644
--- a/stdlib/Test/src/logging.jl
+++ b/stdlib/Test/src/logging.jl
@@ -3,7 +3,7 @@
 using Logging
 import Logging: Info,
     shouldlog, handle_message, min_enabled_level, catch_exceptions
-import Base: contains
+import Base: isfound
 
 #-------------------------------------------------------------------------------
 # Log records
@@ -113,7 +113,7 @@ corresponding to the arguments to passed to `AbstractLogger` via the
 Elements which are present will be matched pairwise with the log record fields
 using `==` by default, with the special cases that `Symbol`s may be used for
 the standard log levels, and `Regex`s in the pattern will match string or
-Symbol fields using `contains`.
+Symbol fields using `isfound`.
 
 # Examples
 
@@ -181,9 +181,9 @@ function match_logs(f, patterns...; match_mode::Symbol=:all, kwargs...)
     logs,value = collect_test_logs(f; kwargs...)
     if match_mode == :all
         didmatch = length(logs) == length(patterns) &&
-            all(contains(l,p) for (p,l) in zip(patterns, logs))
+            all(isfound(p, l) for (p,l) in zip(patterns, logs))
     elseif match_mode == :any
-        didmatch = all(any(contains(l,p) for l in logs) for p in patterns)
+        didmatch = all(any(isfound(p, l) for l in logs) for p in patterns)
     end
     didmatch,logs,value
 end
@@ -202,12 +202,12 @@ function parse_level(level::Symbol)
 end
 
 logfield_contains(a, b) = a == b
-logfield_contains(a, r::Regex) = contains(a, r)
-logfield_contains(a::Symbol, r::Regex) = contains(String(a), r)
+logfield_contains(a, r::Regex) = isfound(r, a)
+logfield_contains(a::Symbol, r::Regex) = isfound(r, String(a))
 logfield_contains(a::LogLevel, b::Symbol) = a == parse_level(b)
 logfield_contains(a, b::Ignored) = true
 
-function contains(r::LogRecord, pattern::Tuple)
+function isfound(r::LogRecord, pattern::Tuple)
     stdfields = (r.level, r.message, r._module, r.group, r.id, r.file, r.line)
     all(logfield_contains(f, p) for (f, p) in zip(stdfields[1:length(pattern)], pattern))
 end
diff --git a/stdlib/Test/test/runtests.jl b/stdlib/Test/test/runtests.jl
index e661a6bcb7736a..9be227a0166468 100644
--- a/stdlib/Test/test/runtests.jl
+++ b/stdlib/Test/test/runtests.jl
@@ -119,87 +119,87 @@ let fails = @testset NoThrowTestSet begin
     end
 
     let str = sprint(show, fails[1])
-        @test contains(str, "Expression: error()")
-        @test contains(str, "Thrown: ErrorException")
+        @test isfound("Expression: error()", str)
+        @test isfound("Thrown: ErrorException", str)
     end
 
     let str = sprint(show, fails[2])
-        @test contains(str, "Expression: 1 + 1")
-        @test contains(str, "No exception thrown")
+        @test isfound("Expression: 1 + 1", str)
+        @test isfound("No exception thrown", str)
     end
 
     let str = sprint(show, fails[3])
-        @test contains(str, "Expression: 1 + 1 == 2 + 2")
-        @test contains(str, "Evaluated: 2 == 4")
+        @test isfound("Expression: 1 + 1 == 2 + 2", str)
+        @test isfound("Evaluated: 2 == 4", str)
     end
 
     let str = sprint(show, fails[4])
-        @test contains(str, "Expression: 1 / 1 ≈ 2 / 1")
-        @test contains(str, "Evaluated: 1.0 ≈ 2.0")
+        @test isfound("Expression: 1 / 1 ≈ 2 / 1", str)
+        @test isfound("Evaluated: 1.0 ≈ 2.0", str)
     end
 
     let str = sprint(show, fails[5])
-        @test contains(str, "Expression: 1 + 0 == 2 + 0 == 3 + 0")
-        @test contains(str, "Evaluated: 1 == 2 == 3")
+        @test isfound("Expression: 1 + 0 == 2 + 0 == 3 + 0", str)
+        @test isfound("Evaluated: 1 == 2 == 3", str)
     end
 
     let str = sprint(show, fails[6])
-        @test contains(str, "Expression: 1 - 2 == 2 - 1")
-        @test contains(str, "Evaluated: -1 == 1")
+        @test isfound("Expression: 1 - 2 == 2 - 1", str)
+        @test isfound("Evaluated: -1 == 1", str)
     end
 
     let str = sprint(show, fails[7])
-        @test contains(str, "Expression: (==)(1:2...)")
-        @test !contains(str, "Evaluated")
+        @test isfound("Expression: (==)(1:2...)", str)
+        @test !isfound("Evaluated", str)
     end
 
     let str = sprint(show, fails[8])
-        @test contains(str, "Expression: isequal(0 / 0, 1 / 0)")
-        @test contains(str, "Evaluated: isequal(NaN, Inf)")
+        @test isfound("Expression: isequal(0 / 0, 1 / 0)", str)
+        @test isfound("Evaluated: isequal(NaN, Inf)", str)
     end
 
     let str = sprint(show, fails[9])
-        @test contains(str, "Expression: isequal(1:2...)")
-        @test contains(str, "Evaluated: isequal(1, 2)")
+        @test isfound("Expression: isequal(1:2...)", str)
+        @test isfound("Evaluated: isequal(1, 2)", str)
     end
 
     let str = sprint(show, fails[10])
-        @test contains(str, "Expression: isapprox(0 / 1, -1 / 0)")
-        @test contains(str, "Evaluated: isapprox(0.0, -Inf)")
+        @test isfound("Expression: isapprox(0 / 1, -1 / 0)", str)
+        @test isfound("Evaluated: isapprox(0.0, -Inf)", str)
     end
 
     let str = sprint(show, fails[11])
-        @test contains(str, "Expression: isapprox(1 / 2, 2 / 1, atol=1 / 1)")
-        @test contains(str, "Evaluated: isapprox(0.5, 2.0; atol=1.0)")
+        @test isfound("Expression: isapprox(1 / 2, 2 / 1, atol=1 / 1)", str)
+        @test isfound("Evaluated: isapprox(0.5, 2.0; atol=1.0)", str)
     end
 
     let str = sprint(show, fails[12])
-        @test contains(str, "Expression: isapprox(1 - 2, 2 - 1; atol=1 - 1)")
-        @test contains(str, "Evaluated: isapprox(-1, 1; atol=0)")
+        @test isfound("Expression: isapprox(1 - 2, 2 - 1; atol=1 - 1)", str)
+        @test isfound("Evaluated: isapprox(-1, 1; atol=0)", str)
     end
 
     let str = sprint(show, fails[13])
-        @test contains(str, "Expression: isapprox(1, 2; k...)")
-        @test contains(str, "Evaluated: isapprox(1, 2; atol=0, nans=true)")
+        @test isfound("Expression: isapprox(1, 2; k...)", str)
+        @test isfound("Evaluated: isapprox(1, 2; atol=0, nans=true)", str)
     end
 
     let str = sprint(show, fails[14])
-        @test contains(str, "Unexpected Pass")
-        @test contains(str, "Expression: true")
+        @test isfound("Unexpected Pass", str)
+        @test isfound("Expression: true", str)
     end
 
     let str = sprint(show, fails[15])
-        @test contains(str, "Expression: ==(1, 1:2...)")
-        @test contains(str, "MethodError: no method matching ==(::$Int, ::$Int, ::$Int)")
+        @test isfound("Expression: ==(1, 1:2...)", str)
+        @test isfound("MethodError: no method matching ==(::$Int, ::$Int, ::$Int)", str)
     end
 end
 
 @testset "printing of a TestSetException" begin
     tse_str = sprint(show, Test.TestSetException(1, 2, 3, 4, Vector{Union{Test.Error, Test.Fail}}()))
-    @test contains(tse_str, "1 passed")
-    @test contains(tse_str, "2 failed")
-    @test contains(tse_str, "3 errored")
-    @test contains(tse_str, "4 broken")
+    @test isfound("1 passed", tse_str)
+    @test isfound("2 failed", tse_str)
+    @test isfound("3 errored", tse_str)
+    @test isfound("4 broken", tse_str)
 end
 
 @test Test.finish(Test.FallbackTestSet()) !== nothing
@@ -513,7 +513,7 @@ Base.getindex(a::SillyArray, i) = rand() > 0.5 ? 0 : false
 @testset "@inferred works with A[i] expressions" begin
     @test @inferred((1:3)[2]) == 2
     test_result = @test_throws ErrorException @inferred(SillyArray()[2])
-    @test contains(test_result.value.msg, "Bool")
+    @test isfound("Bool", test_result.value.msg)
 end
 # Issue #14928
 # Make sure abstract error type works.
@@ -550,30 +550,30 @@ end
     local msg = read(pipeline(ignorestatus(`$(Base.julia_cmd()) --startup-file=no --color=no $f`), stderr=devnull), String)
     # NOTE: This test depends on the code generated by @testset getting compiled,
     # to get good backtraces. If it fails, check the implementation of `testset_beginend`.
-    @test !contains(msg, "do_test(")
-    @test !contains(msg, "include(")
-    @test contains(msg, "at " * f * ":3")
-    @test contains(msg, "at " * f * ":4")
+    @test !isfound("do_test(", msg)
+    @test !isfound("include(", msg)
+    @test isfound("at " * f * ":3", msg)
+    @test isfound("at " * f * ":4", msg)
     rm(f; force=true)
 end
 
 let io = IOBuffer()
     exc = Test.TestSetException(1,2,3,4,Vector{Union{Test.Error, Test.Fail}}())
     Base.showerror(io, exc, backtrace())
-    @test !contains(String(take!(io)), "backtrace()")
+    @test !isfound("backtrace()", String(take!(io)))
 end
 
 @testset "#19750" begin
     io = IOBuffer()
     exc = Test.TestSetException(1,2,3,4,Vector{Union{Test.Error, Test.Fail}}())
     Base.showerror(io, exc, backtrace())
-    @test !contains(String(take!(io)), "backtrace()")
+    @test !isfound("backtrace()", String(take!(io)))
 
     exc = Test.FallbackTestSetException("msg")
     Base.showerror(io, exc, backtrace())
     str = String(take!(io))
-    @test contains(str, "msg")
-    @test !contains(str, "backtrace()")
+    @test isfound("msg", str)
+    @test !isfound("backtrace()", str)
 end
 
 let msg = read(pipeline(ignorestatus(`$(Base.julia_cmd()) --startup-file=no --color=no -e '
@@ -595,15 +595,14 @@ let msg = read(pipeline(ignorestatus(`$(Base.julia_cmd()) --startup-file=no --co
                 @test foo(fill(1., 4)) == 15
             end
         end'`), stderr=devnull), String)
-    @test contains(msg,
-        """
+    @test isfound("""
         Test Summary: | Pass  Fail  Total
         Foo Tests     |    2     2      4
           Animals     |    1     1      2
             Felines   |    1            1
             Canines   |          1      1
           Arrays      |    1     1      2
-        """)
+        """, msg)
 end
 
 # 20489
@@ -646,9 +645,9 @@ end
     """)
 
     local msg = read(pipeline(ignorestatus(`$(Base.julia_cmd()) --startup-file=no --color=no $f`), stderr=devnull), String)
-    @test contains(msg, "at " * f * ":" * "3")
-    @test contains(msg, "at " * f * ":" * "4")
-    @test contains(msg, "at " * f * ":" * "5")
+    @test isfound("at " * f * ":" * "3", msg)
+    @test isfound("at " * f * ":" * "4", msg)
+    @test isfound("at " * f * ":" * "5", msg)
 
     rm(f; force=true)
 end
@@ -663,14 +662,14 @@ end
     x, y = 0.9, 0.1
     @test x ≈ y atol=0.01
     """)
-    @test contains(msg, "Evaluated: 0.9 ≈ 0.1 (atol=0.01)")
+    @test isfound("Evaluated: 0.9 ≈ 0.1 (atol=0.01)", msg)
 
     msg = f("""
     using Test
     x, y = 0.9, 0.1
     @test x ≈ y nans=true atol=0.01
     """)
-    @test contains(msg, "Evaluated: 0.9 ≈ 0.1 (nans=true, atol=0.01)")
+    @test isfound("Evaluated: 0.9 ≈ 0.1 (nans=true, atol=0.01)", msg)
 end
 
 @testset "@test_logs" begin
@@ -810,7 +809,7 @@ end
     """)
     run(pipeline(ignorestatus(`$(Base.julia_cmd()) --startup-file=no --color=no $f`), stderr=err))
     msg = read(err, String)
-    @test contains(msg, "Expected `desc` to be an AbstractTestSet, it is a String")
+    @test isfound("Expected `desc` to be an AbstractTestSet, it is a String", msg)
     rm(f; force=true)
 end
 
diff --git a/test/backtrace.jl b/test/backtrace.jl
index 4477dd1e98be20..a500d7d1977605 100644
--- a/test/backtrace.jl
+++ b/test/backtrace.jl
@@ -161,5 +161,5 @@ end
 let st = stacktrace(bt23971)
     @test StackTraces.is_top_level_frame(st[1])
     @test string(st[1].file) == @__FILE__
-    @test !contains(string(st[2].file), "missing")
+    @test !isfound("missing", string(st[2].file))
 end
diff --git a/test/char.jl b/test/char.jl
index d1e1288ef11cf4..6287d57d580b99 100644
--- a/test/char.jl
+++ b/test/char.jl
@@ -232,7 +232,7 @@ end
         end
         @test sprint(show, c) == rep
         if Base.isoverlong(c)
-            @test contains(sprint(show, "text/plain", c), rep*": [overlong]")
+            @test isfound(rep*": [overlong]", sprint(show, "text/plain", c))
         end
     end
 
diff --git a/test/cmdlineargs.jl b/test/cmdlineargs.jl
index a40767b2855e1f..97be90f5273a5f 100644
--- a/test/cmdlineargs.jl
+++ b/test/cmdlineargs.jl
@@ -222,26 +222,26 @@ let exename = `$(Base.julia_cmd()) --sysimage-native-code=yes --startup-file=no`
     let code = writereadpipeline("code_llvm(stdout, +, (Int64, Int64), false, true)", `$exename -g0`)
         @test code[2]
         code = code[1]
-        @test contains(code, "llvm.module.flags")
-        @test !contains(code, "llvm.dbg.cu")
-        @test !contains(code, "int.jl")
-        @test !contains(code, "Int64")
+        @test isfound("llvm.module.flags", code)
+        @test !isfound("llvm.dbg.cu", code)
+        @test !isfound("int.jl", code)
+        @test !isfound("Int64", code)
     end
     let code = writereadpipeline("code_llvm(stdout, +, (Int64, Int64), false, true)", `$exename -g1`)
         @test code[2]
         code = code[1]
-        @test contains(code, "llvm.module.flags")
-        @test contains(code, "llvm.dbg.cu")
-        @test contains(code, "int.jl")
-        @test !contains(code, "Int64")
+        @test isfound("llvm.module.flags", code)
+        @test isfound("llvm.dbg.cu", code)
+        @test isfound("int.jl", code)
+        @test !isfound("Int64", code)
     end
     let code = writereadpipeline("code_llvm(stdout, +, (Int64, Int64), false, true)", `$exename -g2`)
         @test code[2]
         code = code[1]
-        @test contains(code, "llvm.module.flags")
-        @test contains(code, "llvm.dbg.cu")
-        @test contains(code, "int.jl")
-        @test contains(code, "\"Int64\"")
+        @test isfound("llvm.module.flags", code)
+        @test isfound("llvm.dbg.cu", code)
+        @test isfound("int.jl", code)
+        @test isfound("\"Int64\"", code)
     end
 
     # --check-bounds
@@ -445,9 +445,9 @@ let exename = joinpath(Sys.BINDIR, Base.julia_exename()),
             p = run(pipeline(`$exename --sysimage=$nonexist_image`, stderr=err), wait=false)
             close(err.in)
             let s = read(err, String)
-                @test contains(s, "ERROR: could not load library \"$nonexist_image\"\n")
-                @test !contains(s, "Segmentation fault")
-                @test !contains(s, "EXCEPTION_ACCESS_VIOLATION")
+                @test isfound("ERROR: could not load library \"$nonexist_image\"\n", s)
+                @test !isfound("Segmentation fault", s)
+                @test !isfound("EXCEPTION_ACCESS_VIOLATION", s)
             end
             @test !success(p)
             @test !Base.process_signaled(p)
@@ -503,7 +503,7 @@ for precomp in ("yes", "no")
         -E 'include("____nonexistent_file")'`)
     @test !success
     @test out == ""
-    @test contains(bt, "include_relative(::Module, ::String) at $(joinpath(".", "loading.jl"))")
+    @test isfound("include_relative(::Module, ::String) at $(joinpath(".", "loading.jl"))", bt)
     lno = match(r"at \.[\/\\]loading\.jl:(\d+)", bt)
     @test length(lno.captures) == 1
     @test parse(Int, lno.captures[1]) > 0
diff --git a/test/codegen.jl b/test/codegen.jl
index 475d2e1abe973a..2c960a410988e9 100644
--- a/test/codegen.jl
+++ b/test/codegen.jl
@@ -21,7 +21,7 @@ get_llvm_noopt(@nospecialize(f), @nospecialize(t), strip_ir_metadata=true, dump_
 
 if opt_level > 0
     # Make sure getptls call is removed at IR level with optimization on
-    @test !contains(get_llvm(identity, Tuple{String}), " call ")
+    @test !isfound(" call ", get_llvm(identity, Tuple{String}))
 end
 
 jl_string_ptr(s::String) = ccall(:jl_string_ptr, Ptr{UInt8}, (Any,), s)
@@ -36,7 +36,7 @@ function test_loads_no_call(ir, load_types)
             end
             continue
         end
-        @test !contains(line, " call ")
+        @test !isfound(" call ", line)
         load_split = split(line, " load ", limit=2)
         if !coverage && length(load_split) >= 2
             @test load_idx <= length(load_types)
@@ -89,7 +89,7 @@ end
 
 if opt_level > 0
     # Make sure `jl_string_ptr` is inlined
-    @test !contains(get_llvm(jl_string_ptr, Tuple{String}), " call ")
+    @test !isfound(" call ", get_llvm(jl_string_ptr, Tuple{String}))
     s = "aaa"
     @test jl_string_ptr(s) == pointer_from_objref(s) + sizeof(Int)
     # String
@@ -172,23 +172,23 @@ breakpoint_ptrstruct(a::RealStruct) =
     ccall(:jl_breakpoint, Cvoid, (Ref{PtrStruct},), a)
 
 if opt_level > 0
-    @test !contains(get_llvm(pointer_not_safepoint, Tuple{}), "%gcframe")
+    @test !isfound("%gcframe", get_llvm(pointer_not_safepoint, Tuple{}))
     compare_large_struct_ir = get_llvm(compare_large_struct, Tuple{typeof(create_ref_struct())})
-    @test contains(compare_large_struct_ir, "call i32 @memcmp")
-    @test !contains(compare_large_struct_ir, "%gcframe")
+    @test isfound("call i32 @memcmp", compare_large_struct_ir)
+    @test !isfound("%gcframe", compare_large_struct_ir)
 
-    @test contains(get_llvm(MutableStruct, Tuple{}), "jl_gc_pool_alloc")
+    @test isfound(Tuple{}, get_llvm(MutableStruct), "jl_gc_pool_alloc")
     breakpoint_mutable_ir = get_llvm(breakpoint_mutable, Tuple{MutableStruct})
-    @test !contains(breakpoint_mutable_ir, "%gcframe")
-    @test !contains(breakpoint_mutable_ir, "jl_gc_pool_alloc")
+    @test !isfound("%gcframe", breakpoint_mutable_ir)
+    @test !isfound("jl_gc_pool_alloc", breakpoint_mutable_ir)
 
     breakpoint_badref_ir = get_llvm(breakpoint_badref, Tuple{MutableStruct})
-    @test !contains(breakpoint_badref_ir, "%gcframe")
-    @test !contains(breakpoint_badref_ir, "jl_gc_pool_alloc")
+    @test !isfound("%gcframe", breakpoint_badref_ir)
+    @test !isfound("jl_gc_pool_alloc", breakpoint_badref_ir)
 
     breakpoint_ptrstruct_ir = get_llvm(breakpoint_ptrstruct, Tuple{RealStruct})
-    @test !contains(breakpoint_ptrstruct_ir, "%gcframe")
-    @test !contains(breakpoint_ptrstruct_ir, "jl_gc_pool_alloc")
+    @test !isfound("%gcframe", breakpoint_ptrstruct_ir)
+    @test !isfound("jl_gc_pool_alloc", breakpoint_ptrstruct_ir)
 end
 
 function two_breakpoint(a::Float64)
@@ -206,19 +206,19 @@ end
 if opt_level > 0
     breakpoint_f64_ir = get_llvm((a)->ccall(:jl_breakpoint, Cvoid, (Ref{Float64},), a),
                                  Tuple{Float64})
-    @test !contains(breakpoint_f64_ir, "jl_gc_pool_alloc")
+    @test !isfound("jl_gc_pool_alloc", breakpoint_f64_ir)
     breakpoint_any_ir = get_llvm((a)->ccall(:jl_breakpoint, Cvoid, (Ref{Any},), a),
                                  Tuple{Float64})
-    @test contains(breakpoint_any_ir, "jl_gc_pool_alloc")
+    @test isfound("jl_gc_pool_alloc", breakpoint_any_ir)
     two_breakpoint_ir = get_llvm(two_breakpoint, Tuple{Float64})
-    @test !contains(two_breakpoint_ir, "jl_gc_pool_alloc")
-    @test contains(two_breakpoint_ir, "llvm.lifetime.end")
+    @test !isfound("jl_gc_pool_alloc", two_breakpoint_ir)
+    @test isfound("llvm.lifetime.end", two_breakpoint_ir)
 
     @test load_dummy_ref(1234) === 1234
     load_dummy_ref_ir = get_llvm(load_dummy_ref, Tuple{Int})
-    @test !contains(load_dummy_ref_ir, "jl_gc_pool_alloc")
+    @test !isfound("jl_gc_pool_alloc", load_dummy_ref_ir)
     # Hopefully this is reliable enough. LLVM should be able to optimize this to a direct return.
-    @test contains(load_dummy_ref_ir, "ret $Iptr %0")
+    @test isfound("ret $Iptr %0", load_dummy_ref_ir)
 end
 
 # Issue 22770
@@ -308,11 +308,11 @@ g24108(x::B24108) = f24108(x.x.x)
 @test g22421_2(Ref(7), Ref(8), false) === 24
 
 if opt_level > 0
-    @test !contains(get_llvm(g22421_1, Tuple{Base.RefValue{Int},Base.RefValue{Int},Bool}),
-                    "%gcframe")
-    @test !contains(get_llvm(g22421_2, Tuple{Base.RefValue{Int},Base.RefValue{Int},Bool}),
-                    "%gcframe")
-    @test !contains(get_llvm(g24108, Tuple{B24108}), "%gcframe")
+    @test !isfound("%gcframe",
+                   get_llvm(g22421_1, Tuple{Base.RefValue{Int},Base.RefValue{Int},Bool}))
+    @test !isfound("%gcframe",
+                   get_llvm(g22421_2, Tuple{Base.RefValue{Int},Base.RefValue{Int},Bool}))
+    @test !isfound("%gcframe", get_llvm(g24108, Tuple{B24108}))
 end
 
 # Issue 24632
@@ -323,8 +323,8 @@ end
 
 # A bit coarse-grained perhaps, but ok for now. What we want to check is that the load from
 # the semi-boxed union on the if-branch of the `isa` is not annotated !nonnull
-@test contains(get_llvm_noopt(foo24632, (Bool,), false), "!dereferenceable_or_null")
-@test !contains(get_llvm_noopt(foo24632, (Bool,), false), "!nonnull")
+@test isfound("!dereferenceable_or_null", get_llvm_noopt(foo24632, (Bool,), false))
+@test !isfound("!nonnull", get_llvm_noopt(foo24632, (Bool,), false))
 
 str_22330 = """
 Base.convert(::Type{Array{T,n}}, a::Array) where {T<:Number,n} =
diff --git a/test/compile.jl b/test/compile.jl
index da4b8853bce54a..a65f3c95e19b7b 100644
--- a/test/compile.jl
+++ b/test/compile.jl
@@ -273,7 +273,7 @@ try
         error("__precompile__ disabled test failed")
     catch exc
         isa(exc, ErrorException) || rethrow(exc)
-        contains(exc.msg, "__precompile__(false)") && rethrow(exc)
+        isfound("__precompile__(false)", exc.msg) && rethrow(exc)
     end
 
     # Issue #12720
@@ -340,7 +340,7 @@ try
         error("\"LoadError: break me\" test failed")
     catch exc
         isa(exc, ErrorException) || rethrow(exc)
-        contains(exc.msg, "ERROR: LoadError: break me") && rethrow(exc)
+        isfound("ERROR: LoadError: break me", exc.msg) && rethrow(exc)
     end
 
     # Test transitive dependency for #21266
@@ -458,7 +458,7 @@ let dir = mktempdir()
         let fname = tempname()
             try
                 @test readchomp(pipeline(`$exename -E $(testcode)`, stderr=fname)) == "nothing"
-                @test contains(read(fname, String), Regex("Replacing module `$Test_module`"))
+                @test isfound(Regex("Replacing module `$Test_module`"), read(fname, String))
             finally
                 rm(fname, force=true)
             end
diff --git a/test/compiler/compiler.jl b/test/compiler/compiler.jl
index d6c107b3f669b1..fa1c7e3b4663c5 100644
--- a/test/compiler/compiler.jl
+++ b/test/compiler/compiler.jl
@@ -890,7 +890,7 @@ end
 f22290() = return 3
 for i in 1:3
     ir = sprint(io -> code_llvm(io, f22290, Tuple{}))
-    @test contains(ir, "julia_f22290")
+    @test isfound("julia_f22290", ir)
 end
 
 # constant inference of isdefined
diff --git a/test/core.jl b/test/core.jl
index f68234ca609fdd..f220b48c02c10e 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -1205,9 +1205,9 @@ let
     @test_throws InexactError unsafe_wrap(Array, pointer(a), -3)
     # Misaligned pointer
     res = @test_throws ArgumentError unsafe_wrap(Array, pointer(a) + 1, length(a))
-    @test contains(res.value.msg, "is not properly aligned to $(sizeof(Int)) bytes")
+    @test isfound("is not properly aligned to $(sizeof(Int)) bytes", res.value.msg)
     res = @test_throws ArgumentError unsafe_wrap(Array, pointer(a) + 1, (1, 1))
-    @test contains(res.value.msg, "is not properly aligned to $(sizeof(Int)) bytes")
+    @test isfound("is not properly aligned to $(sizeof(Int)) bytes", res.value.msg)
 end
 
 struct FooBar2515
@@ -4760,7 +4760,7 @@ ptr18236 = cfunction(identity, VecElement{Float64}, Tuple{VecElement{Float64}})
 @eval @noinline f18236(ptr) = ccall(ptr, VecElement{Float64},
                                     (VecElement{Float64},), $v18236)
 @test f18236(ptr18236) === v18236
-@test !contains(sprint(code_llvm, f18236, Tuple{Ptr{Cvoid}}), "double undef")
+@test !isfound("double undef", sprint(code_llvm, f18236, Tuple{Ptr{Cvoid}}))
 # VecElement of struct, not necessarily useful but does have special
 # ABI so should be handled correctly
 # This struct should be small enough to be passed by value in C ABI
diff --git a/test/deprecation_exec.jl b/test/deprecation_exec.jl
index 86ae275dcb0ec4..94c70d5a5a5dca 100644
--- a/test/deprecation_exec.jl
+++ b/test/deprecation_exec.jl
@@ -247,109 +247,109 @@ with_logger(NullLogger()) do
 @testset "Deprecated logging" begin
 
 # Test info
-@test contains(sprint(info, "test"), "INFO:")
-@test contains(sprint(info, "test"), "INFO: test")
-@test contains(sprint(info, "test ", 1, 2, 3), "INFO: test 123")
-@test contains(sprint(io->info(io,"test", prefix="MYINFO: ")), "MYINFO: test")
+@test isfound("INFO:", sprint(info, "test"))
+@test isfound("INFO: test", sprint(info, "test"))
+@test isfound("INFO: test 123", sprint(info, "test ", 1, 2, 3))
+@test isfound("MYINFO: test", sprint(io->info(io,"test", prefix="MYINFO: ")))
 
 # Test warn
-@test contains(sprint(Base.warn_once, "test"), "WARNING: test")
+@test isfound("WARNING: test", sprint(Base.warn_once, "test"))
 @test isempty(sprint(Base.warn_once, "test"))
 
-@test contains(sprint(warn), "WARNING:")
-@test contains(sprint(warn, "test"), "WARNING: test")
-@test contains(sprint(warn, "test ", 1, 2, 3), "WARNING: test 123")
-@test contains(sprint(io->warn(io, "test", prefix="MYWARNING: ")), "MYWARNING: test")
-@test contains(sprint(io->warn(io, "testonce", once=true)), "WARNING: testonce")
+@test isfound("WARNING:", sprint(warn))
+@test isfound("WARNING: test", sprint(warn, "test"))
+@test isfound("WARNING: test 123", sprint(warn, "test ", 1, 2, 3))
+@test isfound("MYWARNING: test", sprint(io->warn(io, "test", prefix="MYWARNING: ")))
+@test isfound("WARNING: testonce", sprint(io->warn(io, "testonce", once=true)))
 @test isempty(sprint(io->warn(io, "testonce", once=true)))
 @test !isempty(sprint(io->warn(io, "testonce", once=true, key=hash("testonce",hash("testanother")))))
 let bt = backtrace()
     ws = split(chomp(sprint(io->warn(io, "test", bt = bt))), '\n')
     bs = split(chomp(sprint(Base.show_backtrace, bt)), '\n')
-    @test contains(ws[1],"WARNING: test")
+    @test isfound("WARNING: test", ws[1])
     for (l,b) in zip(ws[2:end],bs[2:end])
-        @test contains(l, b)
+        @test isfound(b, l)
     end
 end
 
 # PR #16213
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 
 logging(devnull, LogTest, :bar;  kind=:info)
-@test all(contains.(sprint(LogTest.bar), ["WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull, LogTest;  kind=:info)
-@test all(contains.(sprint(LogTest.bar), ["WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull;  kind=:info)
-@test all(contains.(sprint(LogTest.bar), ["WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(kind=:info)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 
 logging(devnull, LogTest, :bar;  kind=:warn)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull, LogTest;  kind=:warn)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull;  kind=:warn)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(kind=:warn)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 
 logging(devnull, LogTest, :bar;  kind=:error)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn"]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn"], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull, LogTest;  kind=:error)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn"]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn"]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn"], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn"], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull;  kind=:error)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn"]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn"]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn"]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn"], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn"], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn"], sprint(foo)))
 
 logging(kind=:error)
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 
 logging(devnull, LogTest, :bar)
 @test sprint(LogTest.bar) == ""
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull, LogTest)
 @test sprint(LogTest.bar) == ""
 @test sprint(LogTest.pooh) == ""
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 logging(devnull)
 @test sprint(LogTest.bar) == ""
@@ -357,9 +357,9 @@ logging(devnull)
 @test sprint(foo) == ""
 
 logging()
-@test all(contains.(sprint(LogTest.bar), ["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""]))
-@test all(contains.(sprint(LogTest.pooh), ["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""]))
-@test all(contains.(sprint(foo), ["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""]))
+@test all(isfound.(["INFO: barinfo", "WARNING: barwarn", "ERROR: \"barerror\""], sprint(LogTest.bar)))
+@test all(isfound.(["INFO: poohinfo", "WARNING: poohwarn", "ERROR: \"pooherror\""], sprint(LogTest.pooh)))
+@test all(isfound.(["INFO: fooinfo", "WARNING: foowarn", "ERROR: \"fooerror\""], sprint(foo)))
 
 end # @testset
 
diff --git a/test/dict.jl b/test/dict.jl
index 0c1f33ec4645bd..2963ba4cb972b3 100644
--- a/test/dict.jl
+++ b/test/dict.jl
@@ -355,9 +355,9 @@ end
     # Check explicitly for the expected strings, since the CPU bitness effects
     # dictionary ordering.
     result = String(take!(buf))
-    @test contains(result, "Dict")
-    @test contains(result, "(1=>2)=>(3=>45)")
-    @test contains(result, "(3=>10)=>(10=>11)")
+    @test isfound("Dict", result)
+    @test isfound("(1=>2)=>(3=>45)", result)
+    @test isfound("(3=>10)=>(10=>11)", result)
 end
 
 mutable struct Alpha end
@@ -368,7 +368,7 @@ Base.show(io::IO, ::Alpha) = print(io,"α")
 
     Base.show(io, MIME("text/plain"), Dict(Alpha()=>1))
     local str = String(take!(sbuff))
-    @test !contains(str, "…")
+    @test !isfound("…", str)
     @test endswith(str, "α => 1")
 end
 
diff --git a/test/docs.jl b/test/docs.jl
index 48d4668a023d2d..11ab575ab03d40 100644
--- a/test/docs.jl
+++ b/test/docs.jl
@@ -669,10 +669,10 @@ end
 @test (@repl :@r_str) !== nothing
 
 # Simple tests for apropos:
-@test contains(sprint(apropos, "pearson"), "cor")
-@test contains(sprint(apropos, r"ind(exes|ices)"), "eachindex")
+@test isfound("cor", sprint(apropos, "pearson"))
+@test isfound("eachindex", sprint(apropos, r"ind(exes|ices)"))
 using Profile
-@test contains(sprint(apropos, "print"), "Profile.print")
+@test isfound("Profile.print", sprint(apropos, "print"))
 
 # Issue #13068.
 
diff --git a/test/env.jl b/test/env.jl
index b3e19250a3ab1b..433b15b255de86 100644
--- a/test/env.jl
+++ b/test/env.jl
@@ -50,8 +50,8 @@ end
         io = IOBuffer()
         show(io, ENV)
         s = String(take!(io))
-        @test contains(s, "$k1=$k1")
-        @test contains(s, "$k2=$k2")
+        @test isfound("$k1=$k1", s)
+        @test isfound("$k2=$k2", s)
 
         @test pop!(ENV, k1) == k1
         @test !haskey(ENV, k1)
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 1841715856e0ad..cea33dd2110815 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -30,8 +30,8 @@ Base.show_method_candidates(buf, Base.MethodError(method_c1,(1, 1, 1)))
 # matches the implicit constructor -> convert method
 Base.show_method_candidates(buf, Base.MethodError(Tuple{}, (1, 1, 1)))
 let mc = String(take!(buf))
-    @test contains(mc, "\nClosest candidates are:\n  Tuple{}")
-    @test !contains(mc, cfile)
+    @test isfound("\nClosest candidates are:\n  Tuple{}", mc)
+    @test !isfound(cfile, mc)
 end
 
 c2line = @__LINE__
@@ -107,12 +107,12 @@ m_error = try TestKWError.method_c6_in_module(1, x=1) catch e; e; end
 showerror(buf, m_error)
 error_out3 = String(take!(buf))
 
-@test contains(error_out, "method_c6(; x)$cfile$(c6line + 1) got unsupported keyword argument \"y\"")
-@test contains(error_out, "method_c6(!Matched::Any; y)$cfile$(c6line + 2)")
-@test contains(error_out1, "method_c6(::Any; y)$cfile$(c6line + 2) got unsupported keyword argument \"x\"")
-@test contains(error_out2, "method_c6_in_module(; x)$cfile$(c6mline + 2) got unsupported keyword argument \"y\"")
-@test contains(error_out2, "method_c6_in_module(!Matched::Any; y)$cfile$(c6mline + 3)")
-@test contains(error_out3, "method_c6_in_module(::Any; y)$cfile$(c6mline + 3) got unsupported keyword argument \"x\"")
+@test isfound("method_c6(; x)$cfile$(c6line + 1) got unsupported keyword argument \"y\"", error_out)
+@test isfound("method_c6(!Matched::Any; y)$cfile$(c6line + 2)", error_out)
+@test isfound("method_c6(::Any; y)$cfile$(c6line + 2) got unsupported keyword argument \"x\"", error_out1)
+@test isfound("method_c6_in_module(; x)$cfile$(c6mline + 2) got unsupported keyword argument \"y\"", error_out2)
+@test isfound("method_c6_in_module(!Matched::Any; y)$cfile$(c6mline + 3)", error_out2)
+@test isfound("method_c6_in_module(::Any; y)$cfile$(c6mline + 3) got unsupported keyword argument \"x\"", error_out3)
 
 c7line = @__LINE__() + 1
 method_c7(a, b; kargs...) = a
@@ -127,7 +127,7 @@ let no_kwsorter_match, e
     no_kwsorter_match() = 0
     no_kwsorter_match(a;y=1) = y
     e = try no_kwsorter_match(y=1) catch ex; ex; end
-    @test contains(sprint(showerror, e), r"no method matching.+\(; y=1\)")
+    @test isfound(r"no method matching.+\(; y=1\)", sprint(showerror, e))
 end
 
 ac15639line = @__LINE__
@@ -195,8 +195,8 @@ let
     f11007(::MethodType11007) = nothing
     err_str = @except_str(invoke(f11007, Tuple{InvokeType11007},
                                  InstanceType11007()), MethodError)
-    @test !contains(err_str, "::$(curmod_prefix)InstanceType11007")
-    @test contains(err_str, "::$(curmod_prefix)InvokeType11007")
+    @test !isfound("::$(curmod_prefix)InstanceType11007", err_str)
+    @test isfound("::$(curmod_prefix)InvokeType11007", err_str)
 end
 
 module __tmp_replutil
@@ -206,37 +206,37 @@ import ..@except_str
 global +
 +() = nothing
 err_str = @except_str 1 + 2 MethodError
-@test contains(err_str, "import Base.+")
+@test isfound("import Base.+", err_str)
 
 err_str = @except_str Float64[](1) MethodError
-@test !contains(err_str, "import Base.Array")
+@test !isfound("import Base.Array", err_str)
 
 Array() = 1
 err_str = @except_str Array(1) MethodError
-@test contains(err_str, "import Base.Array")
+@test isfound("import Base.Array", err_str)
 
 end
 
 let
     g11007(::AbstractVector) = nothing
     err_str = @except_str g11007([[1] [1]]) MethodError
-    @test contains(err_str, "row vector")
-    @test contains(err_str, "column vector")
+    @test isfound("row vector", err_str)
+    @test isfound("column vector", err_str)
 end
 
 struct TypeWithIntParam{T <: Integer} end
 let undefvar
     err_str = @except_strbt sqrt(-1) DomainError
-    @test contains(err_str, "Try sqrt(Complex(x)).")
+    @test isfound("Try sqrt(Complex(x)).", err_str)
     err_str = @except_strbt 2^(1-2) DomainError
-    @test contains(err_str, "Cannot raise an integer x to a negative power -1")
+    @test isfound("Cannot raise an integer x to a negative power -1", err_str)
     err_str = @except_strbt (-1)^0.25 DomainError
-    @test contains(err_str, "Exponentiation yielding a complex result requires a complex argument")
+    @test isfound("Exponentiation yielding a complex result requires a complex argument", err_str)
     A = zeros(10, 10)
     A[2,1] = 1
     A[1,2] = -1
     err_str = @except_strbt eigmax(A) DomainError
-    @test contains(err_str, "DomainError with [0.0 -1.0 …")
+    @test isfound("DomainError with [0.0 -1.0 …", err_str)
 
     err_str = @except_str (1, 2, 3)[4] BoundsError
     @test err_str == "BoundsError: attempt to access (1, 2, 3)\n  at index [4]"
@@ -297,29 +297,29 @@ let err_str,
     j = reinterpret(EightBitTypeT{Int32}, 0x54)
 
     err_str = @except_str Bool() MethodError
-    @test contains(err_str, "MethodError: no method matching Bool()")
+    @test isfound("MethodError: no method matching Bool()", err_str)
     err_str = @except_str :a() MethodError
-    @test contains(err_str, "MethodError: objects of type Symbol are not callable")
+    @test isfound("MethodError: objects of type Symbol are not callable", err_str)
     err_str = @except_str EightBitType() MethodError
-    @test contains(err_str, "MethodError: no method matching $(curmod_prefix)EightBitType()")
+    @test isfound("MethodError: no method matching $(curmod_prefix)EightBitType()", err_str)
     err_str = @except_str i() MethodError
-    @test contains(err_str, "MethodError: objects of type $(curmod_prefix)EightBitType are not callable")
+    @test isfound("MethodError: objects of type $(curmod_prefix)EightBitType are not callable", err_str)
     err_str = @except_str EightBitTypeT() MethodError
-    @test contains(err_str, "MethodError: no method matching $(curmod_prefix)EightBitTypeT()")
+    @test isfound("MethodError: no method matching $(curmod_prefix)EightBitTypeT()", err_str)
     err_str = @except_str EightBitTypeT{Int32}() MethodError
-    @test contains(err_str, "MethodError: no method matching $(curmod_prefix)EightBitTypeT{Int32}()")
+    @test isfound("MethodError: no method matching $(curmod_prefix)EightBitTypeT{Int32}()", err_str)
     err_str = @except_str j() MethodError
-    @test contains(err_str, "MethodError: objects of type $(curmod_prefix)EightBitTypeT{Int32} are not callable")
+    @test isfound("MethodError: objects of type $(curmod_prefix)EightBitTypeT{Int32} are not callable", err_str)
     err_str = @except_str FunctionLike()() MethodError
-    @test contains(err_str, "MethodError: no method matching (::$(curmod_prefix)FunctionLike)()")
+    @test isfound("MethodError: no method matching (::$(curmod_prefix)FunctionLike)()", err_str)
     err_str = @except_str [1,2](1) MethodError
-    @test contains(err_str, "MethodError: objects of type Array{$Int,1} are not callable\nUse square brackets [] for indexing an Array.")
+    @test isfound("MethodError: objects of type Array{$Int,1} are not callable\nUse square brackets [] for indexing an Array.", err_str)
     # Issue 14940
     err_str = @except_str randn(1)() MethodError
-    @test contains(err_str, "MethodError: objects of type Array{Float64,1} are not callable")
+    @test isfound("MethodError: objects of type Array{Float64,1} are not callable", err_str)
 end
 @test repr("text/plain", FunctionLike()) == "(::$(curmod_prefix)FunctionLike) (generic function with 0 methods)"
-@test contains(repr("text/plain", getfield(Base, Symbol("@doc"))), r"^@doc \(macro with \d+ method[s]?\)$")
+@test isfound(r"^@doc \(macro with \d+ method[s]?\)$", repr("text/plain", getfield(Base, Symbol("@doc"))))
 
 method_defs_lineno = @__LINE__() + 1
 Base.Symbol() = throw(ErrorException("1"))
@@ -382,7 +382,7 @@ let err, buf = IOBuffer()
     try Array() catch err end
     Base.show_method_candidates(buf,err)
     @test isa(err, MethodError)
-    @test contains(String(take!(buf)), "Closest candidates are:")
+    @test isfound("Closest candidates are:", String(take!(buf)))
 end
 
 # @macroexpand tests
@@ -449,7 +449,7 @@ foo_9965(x::Int) = 2x
     @test typeof(ex) == MethodError
     io = IOBuffer()
     Base.show_method_candidates(io, ex, pairs((w = true,)))
-    @test contains(String(take!(io)), "got unsupported keyword argument \"w\"")
+    @test isfound("got unsupported keyword argument \"w\"", String(take!(io)))
 end
 
 # Issue #20556
@@ -471,7 +471,7 @@ let
         "MethodError: no method matching $(EnclosingModule.AbstractTypeNoConstructors)()")
 
     # Test that the 'default' sysimg.jl method is not displayed.
-    @test !contains(sprint(showerror, method_error), "where T at sysimg.jl")
+    @test !isfound("where T at sysimg.jl", sprint(showerror, method_error))
 
     # Test that tab-completion will not show the 'default' sysimg.jl method.
     for method_string in REPL.REPLCompletions.complete_methods(:(EnclosingModule.AbstractTypeNoConstructors()))
@@ -491,14 +491,14 @@ end
     end::MethodError
     str = sprint(Base.showerror, ex1)
     @test startswith(str, "MethodError: no method matching f21006(::Tuple{})")
-    @test !contains(str, "The applicable method may be too new")
+    @test !isfound("The applicable method may be too new", str)
 
     # If newer applicable methods are available, world age should be mentioned.
     f21006(x) = x
     @test f21006(()) === ()
     str = sprint(Base.showerror, ex1)
     @test startswith(str, "MethodError: no method matching f21006(::Tuple{})")
-    @test contains(str, "The applicable method may be too new: running in world age $(ex1.world)")
+    @test isfound("The applicable method may be too new: running in world age $(ex1.world)", str)
 
     # This method error should be thrown in a world new enough for `f21006(())`.
     # Also makes sure it's printed correctly.
@@ -509,7 +509,7 @@ end
     end::MethodError
     str = sprint(Base.showerror, ex2)
     @test startswith(str, "MethodError: no method matching f21006(::Tuple{}, ::Tuple{})")
-    @test !contains(str, "The applicable method may be too new")
+    @test !isfound("The applicable method may be too new", str)
 
     # If the method is available in the exception world or if the exception world is invalid,
     # don't warn about world age
@@ -517,7 +517,7 @@ end
                 MethodError(ex1.f, ex1.args, typemax(UInt)))
         str = sprint(Base.showerror, ex3)
         @test startswith(str, "MethodError: no method matching f21006(::Tuple{})")
-        @test !contains(str, "The applicable method may be too new")
+        @test !isfound("The applicable method may be too new", str)
     end
 end
 
diff --git a/test/goto.jl b/test/goto.jl
index 4e8063ffb09902..e4b9fa48e4837d 100644
--- a/test/goto.jl
+++ b/test/goto.jl
@@ -75,7 +75,7 @@ let e = Meta.lower(@__MODULE__, quote
         end
     end)
     @test (e::Expr).head === :error
-    @test contains(e.args[1], r"label \"#\d+#a\" referenced but not defined")
+    @test isfound(r"label \"#\d+#a\" referenced but not defined", e.args[1])
 end
 
 function goto_test5_3()
diff --git a/test/llvmcall.jl b/test/llvmcall.jl
index ddc67eb7ac84e5..0bfc997eb121fe 100644
--- a/test/llvmcall.jl
+++ b/test/llvmcall.jl
@@ -87,7 +87,7 @@ function declared_floor(x::Float64)
 end
 @test declared_floor(4.2) ≈ 4.
 ir = sprint(code_llvm, declared_floor, Tuple{Float64})
-@test contains(ir, "call double @llvm.floor.f64") # should be inlined
+@test isfound("call double @llvm.floor.f64", ir) # should be inlined
 
 function doubly_declared_floor(x::Float64)
     llvmcall(
diff --git a/test/llvmcall2.jl b/test/llvmcall2.jl
index 63f6785f029fba..99cd93a1b3de1e 100644
--- a/test/llvmcall2.jl
+++ b/test/llvmcall2.jl
@@ -7,7 +7,7 @@ function declared_floor(x::Float64)
 end
 @test declared_floor(4.2) == 4.0
 ir = sprint(code_llvm, declared_floor, Tuple{Float64})
-@test contains(ir, "call double @llvm.floor.f64") # should be inlined
+@test isfound("call double @llvm.floor.f64", ir) # should be inlined
 
 function doubly_declared_floor(x::Float64)
     a = ccall("llvm.floor.f64", llvmcall, Float64, (Float64,), x)
diff --git a/test/logging.jl b/test/logging.jl
index 88ebb8f0c226f5..800b51da334b38 100644
--- a/test/logging.jl
+++ b/test/logging.jl
@@ -59,7 +59,7 @@ end
     @test record.file == Base.source_path()
     @test record.line == kwargs[:real_line]
     @test record.id isa Symbol
-    @test contains(String(record.id), r"^.*logging_[[:xdigit:]]{8}$")
+    @test isfound(r"^.*logging_[[:xdigit:]]{8}$", String(record.id))
 
     # User-defined metadata
     @test kwargs[:bar_val] === bar_val
@@ -69,13 +69,13 @@ end
 
     # Keyword values accessible from message block
     record2 = logs[2]
-    @test contains(record2, (Info,"test2"))
+    @test isfound((Info, "test2"), record2)
     kwargs = record2.kwargs
     @test kwargs[:value_in_msg_block] === 1000.0
 
     # Splatting of keywords
     record3 = logs[3]
-    @test contains(record3, (Info,"test3"))
+    @test isfound((Info, "test3"), record3)
     kwargs = record3.kwargs
     @test sort(collect(keys(kwargs))) == [:a, :b]
     @test kwargs[:a] === 1
diff --git a/test/math.jl b/test/math.jl
index 94a97b13e11d74..139f1ab7a1b0e0 100644
--- a/test/math.jl
+++ b/test/math.jl
@@ -43,7 +43,7 @@ end
 
     @test Float16(3.0) < pi
     @test pi < Float16(4.0)
-    @test contains(sprint(show,π),"3.14159")
+    @test isfound("3.14159", sprint(show, π))
     @test widen(pi) === pi
 end
 
diff --git a/test/misc.jl b/test/misc.jl
index 6cdd03a463b5ef..2a66a449a48f26 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -14,7 +14,7 @@ let
         error("unexpected")
     catch ex
         @test isa(ex, AssertionError)
-        @test contains(ex.msg, "1 == 2")
+        @test isfound("1 == 2", ex.msg)
     end
 end
 # test @assert message
@@ -44,8 +44,8 @@ let
         error("unexpected")
     catch ex
         @test isa(ex, AssertionError)
-        @test !contains(ex.msg,  "1 == 2")
-        @test contains(ex.msg, "random_object")
+        @test !isfound("1 == 2", ex.msg)
+        @test isfound("random_object", ex.msg)
     end
 end
 # if the second argument is an expression, c
@@ -82,7 +82,7 @@ let
     exename = Base.julia_cmd()
     script = "$redir_err; module A; f() = 1; end; A.f() = 1"
     warning_str = read(`$exename --warn-overwrite=yes --startup-file=no -e $script`, String)
-    @test contains(warning_str, "f()")
+    @test isfound("f()", warning_str)
 end
 
 # lock / unlock
@@ -371,16 +371,16 @@ end
 
 let optstring = repr("text/plain", Base.JLOptions())
     @test startswith(optstring, "JLOptions(\n")
-    @test !contains(optstring, "Ptr")
+    @test !isfound("Ptr", optstring)
     @test endswith(optstring, "\n)")
-    @test contains(optstring, " = \"")
+    @test isfound(" = \"", optstring)
 end
 let optstring = repr(Base.JLOptions())
     @test startswith(optstring, "JLOptions(")
     @test endswith(optstring, ")")
-    @test !contains(optstring, "\n")
-    @test !contains(optstring, "Ptr")
-    @test contains(optstring, " = \"")
+    @test !isfound("\n", optstring)
+    @test !isfound("Ptr", optstring)
+    @test isfound(" = \"", optstring)
 end
 
 # Base.securezero! functions (#17579)
@@ -579,7 +579,7 @@ end
 
 include("testenv.jl")
 
-let flags = Cmd(filter(a->!contains(a, "depwarn"), collect(test_exeflags)))
+let flags = Cmd(filter(a->!isfound("depwarn", a), collect(test_exeflags)))
     local cmd = `$test_exename $flags deprecation_exec.jl`
 
     if !success(pipeline(cmd; stdout=stdout, stderr=stderr))
diff --git a/test/mpfr.jl b/test/mpfr.jl
index f1396333923494..c1621d95e8fcba 100644
--- a/test/mpfr.jl
+++ b/test/mpfr.jl
@@ -903,7 +903,7 @@ end
         @test x == parse(BigFloat, sx)
         @test ≈(x, parse(BigFloat, scx), rtol=1e-4)
         for s in (sx, scx)
-            @test contains(s, 'e') == contains_e
+            @test isfound('e', s) == contains_e
             @test startswith(s, starts)
             @test endswith(s, ends)
         end
diff --git a/test/offsetarray.jl b/test/offsetarray.jl
index 42e05f1d4c252f..d43b2c0fbc831d 100644
--- a/test/offsetarray.jl
+++ b/test/offsetarray.jl
@@ -164,8 +164,8 @@ str = String(take!(io))
 show(io, parent(v))
 @test str == String(take!(io))
 smry = summary(v)
-@test contains(smry, "OffsetArray{Float64,1")
-@test contains(smry, "with indices -1:1")
+@test isfound("OffsetArray{Float64,1", smry)
+@test isfound("with indices -1:1", smry)
 function cmp_showf(printfunc, io, A)
     ioc = IOContext(io, :limit => true, :compact => true)
     printfunc(ioc, A)
diff --git a/test/osutils.jl b/test/osutils.jl
index ebbd7c9084c3dd..a984fca775b53d 100644
--- a/test/osutils.jl
+++ b/test/osutils.jl
@@ -40,8 +40,8 @@ if Sys.iswindows()
     @testset "path variables use correct path delimiters on windows" begin
         for path in (Base.SYSCONFDIR, Base.DATAROOTDIR, Base.DOCDIR,
                      Base.LIBDIR, Base.PRIVATE_LIBDIR, Base.INCLUDEDIR)
-            @test !contains(path, "/")
-            @test !contains(path, "\\\\")
+            @test !isfound("/", path)
+            @test !isfound("\\\\", path)
         end
     end
 end
diff --git a/test/reduce.jl b/test/reduce.jl
index ed5734dc879b2a..e3ec4b55175920 100644
--- a/test/reduce.jl
+++ b/test/reduce.jl
@@ -323,10 +323,10 @@ struct SomeFunctor end
 @test in(1, 1:3) == true
 @test in(2, 1:3) == true
 
-# contains
+# isfound
 
-@test contains("quick fox", "fox") == true
-@test contains("quick fox", "lazy dog") == false
+@test isfound("fox", "quick fox") == true
+@test isfound("lazy dog", "quick fox") == false
 
 # count
 
@@ -375,7 +375,7 @@ A = reshape(map(UInt8, 1:100), (10,10))
 @test sum([-0.0, -0.0]) === -0.0
 @test prod([-0.0, -0.0]) === 0.0
 
-#contains
+# containment
 let A = Vector(1:10)
     @test A ∋ 5
     @test A ∌ 11
diff --git a/test/reflection.jl b/test/reflection.jl
index dbb544b2e8ac15..c22c11720cd6b4 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -331,20 +331,20 @@ function test_typed_ast_printing(Base.@nospecialize(f), Base.@nospecialize(types
     for str in (sprint(code_warntype, f, types),
                 repr("text/plain", src))
         for var in must_used_vars
-            @test contains(str, string(var))
+            @test isfound(string(var), str)
         end
-        @test !contains(str, "Any")
-        @test !contains(str, "ANY")
+        @test !isfound("Any", str)
+        @test !isfound("ANY", str)
         # Check that we are not printing the bare slot numbers
         for i in 1:length(src.slotnames)
             name = src.slotnames[i]
             if name in dupnames
-                if name in must_used_vars && contains(str, Regex("_$i\\b"))
+                if name in must_used_vars && isfound(Regex("_$i\\b"), str)
                     must_used_checked[name] = true
                     global used_dup_var_tested15714 = true
                 end
             else
-                @test !contains(str, Regex("_$i\\b"))
+                @test !isfound(Regex("_$i\\b"), str)
                 if name in must_used_vars
                     global used_unique_var_tested15714 = true
                 end
@@ -363,7 +363,7 @@ function test_typed_ast_printing(Base.@nospecialize(f), Base.@nospecialize(types
     # Use the variable names that we know should be present in the optimized AST
     for i in 2:length(src.slotnames)
         name = src.slotnames[i]
-        if name in must_used_vars && contains(str, Regex("_$i\\b"))
+        if name in must_used_vars && isfound(Regex("_$i\\b"), str)
             must_used_checked[name] = true
         end
     end
diff --git a/test/regex.jl b/test/regex.jl
index 7db1e282907b2b..754fd6af4c7020 100644
--- a/test/regex.jl
+++ b/test/regex.jl
@@ -31,7 +31,7 @@ show(buf, r"")
 @test read(buf, String) == "r\"\""
 
 # see #10994, #11447: PCRE2 allows NUL chars in the pattern
-@test contains("a\0b", Regex("^a\0b\$"))
+@test isfound(Regex("^a\0b\$"), "a\0b")
 
 # regex match / search string must be a String
 @test_throws ArgumentError match(r"test", GenericString("this is a test"))
diff --git a/test/show.jl b/test/show.jl
index 0ffda8661e1e72..e81fa7e0b3a97d 100644
--- a/test/show.jl
+++ b/test/show.jl
@@ -432,7 +432,7 @@ let a = Expr(:quote,Expr(:$,:x8d003))
 end
 
 # issue #9865
-@test contains(replstr(Set(1:100)), r"^Set\(\[.+….+\]\)$")
+@test isfound(r"^Set\(\[.+….+\]\)$", replstr(Set(1:100)))
 
 # issue #11413
 @test string(:(*{1, 2})) == "*{1, 2}"
@@ -538,7 +538,7 @@ let filename = tempname()
     @test ret == [2]
 
     # stdin is unavailable on the workers. Run test on master.
-    @test contains(read(filename, String), "WARNING: hello")
+    @test isfound("WARNING: hello", read(filename, String))
     ret = eval(Main, quote
         remotecall_fetch(1, $filename) do fname
             open(fname) do f
@@ -549,7 +549,7 @@ let filename = tempname()
         end
     end)
 
-    @test contains(ret, "WARNING: hello")
+    @test isfound("WARNING: hello", ret)
     rm(filename)
 end
 
@@ -580,28 +580,28 @@ end
 @test !Base.inbase(Core)
 
 let repr = sprint(show, "text/plain", methods(Base.inbase))
-    @test contains(repr, "inbase(m::Module)")
+    @test isfound("inbase(m::Module)", repr)
 end
 let repr = sprint(show, "text/html", methods(Base.inbase))
-    @test contains(repr, "inbase(m::<b>Module</b>)")
+    @test isfound("inbase(m::<b>Module</b>)", repr)
 end
 
 f5971(x, y...; z=1, w...) = nothing
 let repr = sprint(show, "text/plain", methods(f5971))
-    @test contains(repr, "f5971(x, y...; z, w...)")
+    @test isfound("f5971(x, y...; z, w...)", repr)
 end
 let repr = sprint(show, "text/html", methods(f5971))
-    @test contains(repr, "f5971(x, y...; <i>z, w...</i>)")
+    @test isfound("f5971(x, y...; <i>z, w...</i>)", repr)
 end
 f16580(x, y...; z=1, w=y+x, q...) = nothing
 let repr = sprint(show, "text/html", methods(f16580))
-    @test contains(repr, "f16580(x, y...; <i>z, w, q...</i>)")
+    @test isfound("f16580(x, y...; <i>z, w, q...</i>)", repr)
 end
 
 if isempty(Base.GIT_VERSION_INFO.commit)
-    @test contains(Base.url(which(sin, (Float64,))), "https://github.com/JuliaLang/julia/tree/v$VERSION/base/special/trig.jl#L")
+    @test isfound("https://github.com/JuliaLang/julia/tree/v$VERSION/base/special/trig.jl#L", Base.url(which(sin, (Float64,))))
 else
-    @test contains(Base.url(which(sin, (Float64,))), "https://github.com/JuliaLang/julia/tree/$(Base.GIT_VERSION_INFO.commit)/base/special/trig.jl#L")
+    @test isfound("https://github.com/JuliaLang/julia/tree/$(Base.GIT_VERSION_INFO.commit)/base/special/trig.jl#L", Base.url(which(sin, (Float64,))))
 end
 
 # print_matrix should be able to handle small and large objects easily, test by
@@ -611,7 +611,7 @@ end
 @test replstr(Matrix(1.0I, 10, 10)) == "10×10 Array{Float64,2}:\n 1.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0\n 0.0  1.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0\n 0.0  0.0  1.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0\n 0.0  0.0  0.0  1.0  0.0  0.0  0.0  0.0  0.0  0.0\n 0.0  0.0  0.0  0.0  1.0  0.0  0.0  0.0  0.0  0.0\n 0.0  0.0  0.0  0.0  0.0  1.0  0.0  0.0  0.0  0.0\n 0.0  0.0  0.0  0.0  0.0  0.0  1.0  0.0  0.0  0.0\n 0.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0  0.0  0.0\n 0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0  0.0\n 0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0"
 # an array too long vertically to fit on screen, and too long horizontally:
 @test replstr(Vector(1.:100.)) == "100-element Array{Float64,1}:\n   1.0\n   2.0\n   3.0\n   4.0\n   5.0\n   6.0\n   7.0\n   8.0\n   9.0\n  10.0\n   ⋮  \n  92.0\n  93.0\n  94.0\n  95.0\n  96.0\n  97.0\n  98.0\n  99.0\n 100.0"
-@test contains(replstr(Vector(1.:100.)'), r"1×100 (LinearAlgebra\.)?Adjoint{Float64,Array{Float64,1}}:\n 1.0  2.0  3.0  4.0  5.0  6.0  7.0  …  95.0  96.0  97.0  98.0  99.0  100.0")
+@test isfound(r"1×100 (LinearAlgebra\.)?Adjoint{Float64,Array{Float64,1}}:\n 1.0  2.0  3.0  4.0  5.0  6.0  7.0  …  95.0  96.0  97.0  98.0  99.0  100.0", replstr(Vector(1.:100.)'))
 # too big in both directions to fit on screen:
 @test replstr((1.:100.)*(1:100)') == "100×100 Array{Float64,2}:\n   1.0    2.0    3.0    4.0    5.0    6.0  …    97.0    98.0    99.0    100.0\n   2.0    4.0    6.0    8.0   10.0   12.0      194.0   196.0   198.0    200.0\n   3.0    6.0    9.0   12.0   15.0   18.0      291.0   294.0   297.0    300.0\n   4.0    8.0   12.0   16.0   20.0   24.0      388.0   392.0   396.0    400.0\n   5.0   10.0   15.0   20.0   25.0   30.0      485.0   490.0   495.0    500.0\n   6.0   12.0   18.0   24.0   30.0   36.0  …   582.0   588.0   594.0    600.0\n   7.0   14.0   21.0   28.0   35.0   42.0      679.0   686.0   693.0    700.0\n   8.0   16.0   24.0   32.0   40.0   48.0      776.0   784.0   792.0    800.0\n   9.0   18.0   27.0   36.0   45.0   54.0      873.0   882.0   891.0    900.0\n  10.0   20.0   30.0   40.0   50.0   60.0      970.0   980.0   990.0   1000.0\n   ⋮                                  ⋮    ⋱                                 \n  92.0  184.0  276.0  368.0  460.0  552.0     8924.0  9016.0  9108.0   9200.0\n  93.0  186.0  279.0  372.0  465.0  558.0     9021.0  9114.0  9207.0   9300.0\n  94.0  188.0  282.0  376.0  470.0  564.0     9118.0  9212.0  9306.0   9400.0\n  95.0  190.0  285.0  380.0  475.0  570.0     9215.0  9310.0  9405.0   9500.0\n  96.0  192.0  288.0  384.0  480.0  576.0  …  9312.0  9408.0  9504.0   9600.0\n  97.0  194.0  291.0  388.0  485.0  582.0     9409.0  9506.0  9603.0   9700.0\n  98.0  196.0  294.0  392.0  490.0  588.0     9506.0  9604.0  9702.0   9800.0\n  99.0  198.0  297.0  396.0  495.0  594.0     9603.0  9702.0  9801.0   9900.0\n 100.0  200.0  300.0  400.0  500.0  600.0     9700.0  9800.0  9900.0  10000.0"
 
@@ -659,20 +659,13 @@ end
 
 # test structured zero matrix printing for select structured types
 let A = reshape(1:16, 4, 4)
-    @test contains(replstr(Diagonal(A)),
-        r"4×4 (LinearAlgebra\.)?Diagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  ⋅   ⋅   ⋅\n ⋅  6   ⋅   ⋅\n ⋅  ⋅  11   ⋅\n ⋅  ⋅   ⋅  16")
-    @test contains(replstr(Bidiagonal(A, :U)),
-        r"4×4 (LinearAlgebra\.)?Bidiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  5   ⋅   ⋅\n ⋅  6  10   ⋅\n ⋅  ⋅  11  15\n ⋅  ⋅   ⋅  16")
-    @test contains(replstr(Bidiagonal(A, :L)),
-        r"4×4 (LinearAlgebra\.)?Bidiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  ⋅   ⋅   ⋅\n 2  6   ⋅   ⋅\n ⋅  7  11   ⋅\n ⋅  ⋅  12  16")
-    @test contains(replstr(SymTridiagonal(A + A')),
-        r"4×4 (LinearAlgebra\.)?SymTridiagonal{Int(32|64),Array{Int(32|64),1}}:\n 2   7   ⋅   ⋅\n 7  12  17   ⋅\n ⋅  17  22  27\n ⋅   ⋅  27  32")
-    @test contains(replstr(Tridiagonal(diag(A, -1), diag(A), diag(A, +1))),
-        r"4×4 (LinearAlgebra\.)?Tridiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  5   ⋅   ⋅\n 2  6  10   ⋅\n ⋅  7  11  15\n ⋅  ⋅  12  16")
-    @test contains(replstr(UpperTriangular(copy(A))),
-        r"4×4 (LinearAlgebra\.)?UpperTriangular{Int(32|64),Array{Int(32|64),2}}:\n 1  5   9  13\n ⋅  6  10  14\n ⋅  ⋅  11  15\n ⋅  ⋅   ⋅  16")
-    @test contains(replstr(LowerTriangular(copy(A))),
-        r"4×4 (LinearAlgebra\.)?LowerTriangular{Int(32|64),Array{Int(32|64),2}}:\n 1  ⋅   ⋅   ⋅\n 2  6   ⋅   ⋅\n 3  7  11   ⋅\n 4  8  12  16")
+    @test isfound(r"4×4 (LinearAlgebra\.)?Diagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  ⋅   ⋅   ⋅\n ⋅  6   ⋅   ⋅\n ⋅  ⋅  11   ⋅\n ⋅  ⋅   ⋅  16", replstr(Diagonal(A)))
+    @test isfound(r"4×4 (LinearAlgebra\.)?Bidiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  5   ⋅   ⋅\n ⋅  6  10   ⋅\n ⋅  ⋅  11  15\n ⋅  ⋅   ⋅  16", replstr(Bidiagonal(A, :U)))
+    @test isfound(r"4×4 (LinearAlgebra\.)?Bidiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  ⋅   ⋅   ⋅\n 2  6   ⋅   ⋅\n ⋅  7  11   ⋅\n ⋅  ⋅  12  16", replstr(Bidiagonal(A, :L)))
+    @test isfound(r"4×4 (LinearAlgebra\.)?SymTridiagonal{Int(32|64),Array{Int(32|64),1}}:\n 2   7   ⋅   ⋅\n 7  12  17   ⋅\n ⋅  17  22  27\n ⋅   ⋅  27  32", replstr(SymTridiagonal(A + A')))
+    @test isfound(r"4×4 (LinearAlgebra\.)?Tridiagonal{Int(32|64),Array{Int(32|64),1}}:\n 1  5   ⋅   ⋅\n 2  6  10   ⋅\n ⋅  7  11  15\n ⋅  ⋅  12  16", replstr(Tridiagonal(diag(A, -1), diag(A), diag(A, +1))))
+    @test isfound(r"4×4 (LinearAlgebra\.)?UpperTriangular{Int(32|64),Array{Int(32|64),2}}:\n 1  5   9  13\n ⋅  6  10  14\n ⋅  ⋅  11  15\n ⋅  ⋅   ⋅  16", replstr(UpperTriangular(copy(A))))
+    @test isfound(r"4×4 (LinearAlgebra\.)?LowerTriangular{Int(32|64),Array{Int(32|64),2}}:\n 1  ⋅   ⋅   ⋅\n 2  6   ⋅   ⋅\n 3  7  11   ⋅\n 4  8  12  16", replstr(LowerTriangular(copy(A))))
 end
 
 # Vararg methods in method tables
@@ -744,8 +737,8 @@ end
 @test string(Tuple{Array}) == "Tuple{Array}"
 
 # PR #16651
-@test !contains(repr(fill(1.,10,10)), "\u2026")
-@test contains(sprint((io, x) -> show(IOContext(io, :limit => true), x), fill(1.,30,30)), "\u2026")
+@test !isfound("\u2026", repr(fill(1.,10,10)))
+@test isfound("\u2026", sprint((io, x) -> show(IOContext(io, :limit => true), x), fill(1.,30,30)))
 
 # showcompact() also sets :multiline=>false (#16817)
 let io = IOBuffer(),
@@ -788,12 +781,12 @@ let repr = sprint(dump, Int64)
 end
 let repr = sprint(dump, Any)
     @test length(repr) == 4
-    @test contains(repr, r"^Any\n")
+    @test isfound(r"^Any\n", repr)
     @test endswith(repr, '\n')
 end
 let repr = sprint(dump, Integer)
-    @test contains(repr, "Integer <: Real")
-    @test !contains(repr, "Any")
+    @test isfound("Integer <: Real", repr)
+    @test !isfound("Any", repr)
 end
 let repr = sprint(dump, Union{Integer, Float32})
     @test repr == "Union{Integer, Float32}\n" || repr == "Union{Float32, Integer}\n"
@@ -892,7 +885,7 @@ let m = which(T20332{Int}(), (Int,)),
     mi = ccall(:jl_specializations_get_linfo, Ref{Core.MethodInstance}, (Any, Any, Any, UInt),
                m, Tuple{T20332{T}, Int} where T, Core.svec(), typemax(UInt))
     # test that this doesn't throw an error
-    @test contains(repr(mi), "MethodInstance for")
+    @test isfound("MethodInstance for", repr(mi))
 end
 
 @test sprint(show, Main) == "Main"
@@ -946,7 +939,7 @@ end
 
 let io = IOBuffer()
     show(io, MIME"text/html"(), f_with_params.body.name.mt)
-    @test contains(String(take!(io)), "f_with_params")
+    @test isfound("f_with_params", String(take!(io)))
 end
 
 @testset "printing of Val's" begin
@@ -1082,7 +1075,7 @@ end
     io = IOBuffer()
     show(io, "text/html", m)
     s = String(take!(io))
-    @test contains(s, " in Base.Math ")
+    @test isfound(" in Base.Math ", s)
 end
 
 module TestShowType
@@ -1142,11 +1135,11 @@ end
 
     display(td, d)
     result = String(take!(td.io))
-    @test contains(result, summary(d))
+    @test isfound(summary(d), result)
 
     # Is every pair in the string?
     for el in d
-        @test contains(result, string(el))
+        @test isfound(string(el), result)
     end
 end
 
@@ -1154,14 +1147,14 @@ end
     K20111(x) = y -> x
     buf = IOBuffer()
     show(buf, methods(K20111(1)))
-    @test contains(String(take!(buf)), " 1 method for generic function")
+    @test isfound(" 1 method for generic function", String(take!(buf)))
 end
 
 @generated f22798(x::Integer, y) = :x
 @testset "#22798" begin
     buf = IOBuffer()
     show(buf, methods(f22798))
-    @test contains(String(take!(buf)), "f22798(x::Integer, y)")
+    @test isfound("f22798(x::Integer, y)", String(take!(buf)))
 end
 
 @testset "Intrinsic printing" begin
@@ -1169,8 +1162,8 @@ end
     let io = IOBuffer()
         show(io, MIME"text/plain"(), Core.Intrinsics.arraylen)
         str = String(take!(io))
-        @test contains(str, "arraylen")
-        @test contains(str, "(intrinsic function")
+        @test isfound("arraylen", str)
+        @test isfound("(intrinsic function", str)
     end
 end
 
diff --git a/test/spawn.jl b/test/spawn.jl
index a468df6741de59..c7abfbe61e29f7 100644
--- a/test/spawn.jl
+++ b/test/spawn.jl
@@ -48,8 +48,8 @@ end
 @test length(run(pipeline(`$echocmd hello`, sortcmd), wait=false).processes) == 2
 
 out = read(`$echocmd hello` & `$echocmd world`, String)
-@test contains(out,"world")
-@test contains(out,"hello")
+@test isfound("world", out)
+@test isfound("hello", out)
 @test read(pipeline(`$echocmd hello` & `$echocmd world`, sortcmd), String) == "hello\nworld\n"
 
 @test (run(`$printfcmd "       \033[34m[stdio passthrough ok]\033[0m\n"`); true)
diff --git a/test/stacktraces.jl b/test/stacktraces.jl
index 59e9268c892dd3..ed4f5294956349 100644
--- a/test/stacktraces.jl
+++ b/test/stacktraces.jl
@@ -141,7 +141,7 @@ end
 
 # Test that `removes_frames!` can correctly remove frames from within the module
 trace = StackTracesTestMod.unfiltered_stacktrace()
-@test contains(string(trace), "unfiltered_stacktrace")
+@test isfound("unfiltered_stacktrace", string(trace))
 
 trace = StackTracesTestMod.filtered_stacktrace()
-@test !contains(string(trace), "filtered_stacktrace")
+@test !isfound("filtered_stacktrace", string(trace))
diff --git a/test/staged.jl b/test/staged.jl
index 8d1cb76be7253e..b677ab65d762d2 100644
--- a/test/staged.jl
+++ b/test/staged.jl
@@ -274,10 +274,10 @@ end
 let a = Any[]
     @test f23168(a, 3) == (6, Int)
     @test a == [1, 6, 3]
-    @test contains(string(code_lowered(f23168, (Vector{Any},Int))), "x + x")
-    @test contains(string(Base.uncompressed_ast(first(methods(f23168)))), "2 * x")
-    @test contains(string(code_lowered(f23168, (Vector{Any},Int), generated=false)), "2 * x")
-    @test contains(string(code_typed(f23168, (Vector{Any},Int))), "(Base.add_int)(x, x)")
+    @test isfound("x + x", string(code_lowered(f23168, (Vector{Any},Int))))
+    @test isfound("2 * x", string(Base.uncompressed_ast(first(methods(f23168)))))
+    @test isfound("2 * x", string(code_lowered(f23168, (Vector{Any},Int), generated=false)))
+    @test isfound("(Base.add_int)(x, x)", string(code_typed(f23168, (Vector{Any},Int))))
 end
 
 # issue #18747
diff --git a/test/strings/search.jl b/test/strings/search.jl
index b494d72c83ee4d..8af8509340e2a1 100644
--- a/test/strings/search.jl
+++ b/test/strings/search.jl
@@ -313,9 +313,9 @@ end
 @test findfirst(r"az", "foo,bar,baz") == 10:11
 @test findnext(r"az", "foo,bar,baz", 12) == 0:-1
 
-# contains with a String and Char needle
-@test contains("foo", "o")
-@test contains("foo", 'o')
+# isfound with a String and Char needle
+@test isfound("o", "foo")
+@test isfound('o', "foo")
 
 @test_throws ErrorException "ab" ∈ "abc"
 
@@ -327,4 +327,4 @@ end
 
 @test @inferred findall(equalto('a'), "éa") == [3]
 @test @inferred findall(equalto('€'), "€€") == [1, 4]
-@test @inferred isempty(findall(equalto('é'), ""))
\ No newline at end of file
+@test @inferred isempty(findall(equalto('é'), ""))
diff --git a/test/strings/types.jl b/test/strings/types.jl
index 1b12b7cf634c83..26ba7222d0a18a 100644
--- a/test/strings/types.jl
+++ b/test/strings/types.jl
@@ -154,8 +154,8 @@ end
 @test parse(Float32, SubString("10",1,1)) === 1.0f0
 
 # issue #5870
-@test !contains(SubString("",1,0), Regex("aa"))
-@test contains(SubString("",1,0), Regex(""))
+@test !isfound(Regex("aa"), SubString("",1,0))
+@test isfound(Regex(""), SubString("",1,0))
 
 # isvalid, length, prevind, nextind for SubString{String}
 let s = "lorem ipsum", sdict = Dict(
diff --git a/test/threads.jl b/test/threads.jl
index a05415b4dfe9ce..d60af1974cf633 100644
--- a/test/threads.jl
+++ b/test/threads.jl
@@ -475,8 +475,8 @@ test_nested_loops()
                      append=false))
         out = readchomp(joinpath(dir, "out.txt"))
         err = readchomp(joinpath(dir, "err.txt"))
-        @test contains(out, "libat_store") || contains(out, "atomic_store")
-        @test !contains(err, "__atomic_store")
+        @test isfound("libat_store", out) || isfound("atomic_store", out)
+        @test !isfound("__atomic_store", err)
     end
 end
 
diff --git a/test/worlds.jl b/test/worlds.jl
index db1d03755e2d90..0bc9e72cd8a314 100644
--- a/test/worlds.jl
+++ b/test/worlds.jl
@@ -152,7 +152,7 @@ let ex = t265.exception
         The applicable method may be too new: running in world age $wc265, while current world is $wc."""
     @test startswith(str, cmps)
     cmps = "\n  h265() at $loc_h265 (method too new to be called from this world context.)"
-    @test contains(str, cmps)
+    @test isfound(cmps, str)
 end
 
 # test for generated function correctness