diff --git a/test/irb/test_debug_cmd.rb b/test/irb/test_debug_cmd.rb
new file mode 100644
index 000000000..11905ac60
--- /dev/null
+++ b/test/irb/test_debug_cmd.rb
@@ -0,0 +1,249 @@
+# frozen_string_literal: false
+
+require "pty" unless RUBY_ENGINE == 'truffleruby'
+require "tempfile"
+
+require_relative "helper"
+
+module TestIRB
+  class DebugCommandTestCase < TestCase
+    IRB_AND_DEBUGGER_OPTIONS = {
+      "RUBY_DEBUG_NO_RELINE" => "true", "NO_COLOR" => "true", "RUBY_DEBUG_HISTORY_FILE" => '', "USE_SINGLELINE" => "true"
+    }
+
+    def test_backtrace
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        def foo
+          binding.irb
+        end
+        foo
+      RUBY
+
+      output = run_ruby_file do
+        type "backtrace"
+        type "q!"
+      end
+
+      assert_match(/\(rdbg:irb\) backtrace/, output)
+      assert_match(/Object#foo at #{@ruby_file.to_path}/, output)
+    end
+
+    def test_debug
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'ruby'
+        binding.irb
+        puts "hello"
+      ruby
+
+      output = run_ruby_file do
+        type "debug"
+        type "next"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg\) next/, output)
+      assert_match(/=>   2\| puts "hello"/, output)
+    end
+
+    def test_next
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'ruby'
+        binding.irb
+        puts "hello"
+      ruby
+
+      output = run_ruby_file do
+        type "next"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) next/, output)
+      assert_match(/=>   2\| puts "hello"/, output)
+    end
+
+    def test_break
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        binding.irb
+        puts "Hello"
+      RUBY
+
+      output = run_ruby_file do
+        type "break 2"
+        type "continue"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) break/, output)
+      assert_match(/=>   2\| puts "Hello"/, output)
+    end
+
+    def test_delete
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        binding.irb
+        puts "Hello"
+        binding.irb
+        puts "World"
+      RUBY
+
+      output = run_ruby_file do
+        type "break 4"
+        type "continue"
+        type "delete 0"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) delete/, output)
+      assert_match(/deleted: #0  BP - Line/, output)
+    end
+
+    def test_step
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        def foo
+          puts "Hello"
+        end
+        binding.irb
+        foo
+      RUBY
+
+      output = run_ruby_file do
+        type "step"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) step/, output)
+      assert_match(/=>   2|   puts "Hello"/, output)
+    end
+
+    def test_continue
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        binding.irb
+        puts "Hello"
+        binding.irb
+        puts "World"
+      RUBY
+
+      output = run_ruby_file do
+        type "continue"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) continue/, output)
+      assert_match(/=> 3: binding.irb/, output)
+    end
+
+    def test_finish
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        def foo
+          binding.irb
+          puts "Hello"
+        end
+        foo
+      RUBY
+
+      output = run_ruby_file do
+        type "finish"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) finish/, output)
+      assert_match(/=>   4\| end/, output)
+    end
+
+    def test_info
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        def foo
+          a = "He" + "llo"
+          binding.irb
+        end
+        foo
+      RUBY
+
+      output = run_ruby_file do
+        type "info"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) info/, output)
+      assert_match(/%self = main/, output)
+      assert_match(/a = "Hello"/, output)
+    end
+
+    def test_catch
+      omit if RUBY_ENGINE == 'truffleruby'
+      write_ruby <<~'RUBY'
+        binding.irb
+        1 / 0
+      RUBY
+
+      output = run_ruby_file do
+        type "catch ZeroDivisionError"
+        type "continue"
+        type "continue"
+      end
+
+      assert_match(/\(rdbg:irb\) catch/, output)
+      assert_match(/Stop by #0  BP - Catch  "ZeroDivisionError"/, output)
+    end
+
+    private
+
+    def run_ruby_file(&block)
+      cmd = "ruby -Ilib #{@ruby_file.to_path}"
+      @commands = []
+      lines = []
+
+      yield
+
+      PTY.spawn(IRB_AND_DEBUGGER_OPTIONS, cmd) do |read, write, pid|
+        Timeout.timeout(3) do
+          while line = safe_gets(read)
+            lines << line
+
+            # means the breakpoint is triggered
+            if line.match?(/binding\.irb/)
+              while command = @commands.shift
+                write.puts(command)
+              end
+            end
+          end
+        end
+      end
+
+      lines.join
+    rescue Timeout::Error
+      message = <<~MSG
+      Test timedout.
+
+      #{'=' * 30} OUTPUT #{'=' * 30}
+        #{lines.map { |l| "  #{l}" }.join}
+      #{'=' * 27} END OF OUTPUT #{'=' * 27}
+      MSG
+      assert_block(message) { false }
+    end
+
+    # read.gets could raise exceptions on some platforms
+    # https://github.com/ruby/ruby/blob/master/ext/pty/pty.c#L729-L736
+    def safe_gets(read)
+      read.gets
+    rescue Errno::EIO
+      nil
+    end
+
+    def type(command)
+      @commands << command
+    end
+
+    def write_ruby(program)
+      @ruby_file = Tempfile.create(%w{irb- .rb})
+      @ruby_file.write(program)
+      @ruby_file.close
+    end
+  end
+end