diff --git a/src/build/arg/mod.rs b/src/build/arg/mod.rs
index 25303145e11..ade62d78ce2 100644
--- a/src/build/arg/mod.rs
+++ b/src/build/arg/mod.rs
@@ -1701,6 +1701,7 @@ impl<'help> Arg<'help> {
     }
 
     /// Specifies the name of the [`ArgGroup`] the argument belongs to.
+    /// **The group must be defined separately via `App::group`.**
     ///
     /// # Examples
     ///
@@ -1716,7 +1717,7 @@ impl<'help> Arg<'help> {
     /// was one of said arguments.
     ///
     /// ```rust
-    /// # use clap::{App, Arg};
+    /// # use clap::{App, Arg, ArgGroup};
     /// let m = App::new("prog")
     ///     .arg(Arg::new("debug")
     ///         .long("debug")
@@ -1724,6 +1725,7 @@ impl<'help> Arg<'help> {
     ///     .arg(Arg::new("verbose")
     ///         .long("verbose")
     ///         .group("mode"))
+    ///     .group(ArgGroup::new("mode"))
     ///     .get_matches_from(vec![
     ///         "prog", "--debug"
     ///     ]);
@@ -1736,6 +1738,7 @@ impl<'help> Arg<'help> {
     }
 
     /// Specifies the names of multiple [`ArgGroup`]'s the argument belongs to.
+    /// **The groups must be defined separately via `App::group`.**
     ///
     /// # Examples
     ///
@@ -1751,7 +1754,7 @@ impl<'help> Arg<'help> {
     /// was one of said arguments.
     ///
     /// ```rust
-    /// # use clap::{App, Arg};
+    /// # use clap::{App, Arg, ArgGroup};
     /// let m = App::new("prog")
     ///     .arg(Arg::new("debug")
     ///         .long("debug")
@@ -1759,6 +1762,8 @@ impl<'help> Arg<'help> {
     ///     .arg(Arg::new("verbose")
     ///         .long("verbose")
     ///         .groups(&["mode", "verbosity"]))
+    ///     .group(ArgGroup::new("mode"))
+    ///     .group(ArgGroup::new("verbosity"))
     ///     .get_matches_from(vec![
     ///         "prog", "--debug"
     ///     ]);
@@ -3810,7 +3815,7 @@ impl<'help> Arg<'help> {
     ///     ]);
     ///
     /// assert!(res.is_ok());
-    /// assert_eq!(res.unwrap().value_of("config"), None);
+    /// assert_eq!(res.unwrap().value_of("cfg"), Some(""));
     /// ```
     /// [`ArgSettings::TakesValue`]: ./enum.ArgSettings.html#variant.TakesValue
     #[inline]
diff --git a/tests/groups.rs b/tests/groups.rs
index 40bd3b14291..e977e81f1a7 100644
--- a/tests/groups.rs
+++ b/tests/groups.rs
@@ -281,6 +281,7 @@ fn group_acts_like_arg() {
     let m = App::new("prog")
         .arg(Arg::new("debug").long("debug").group("mode"))
         .arg(Arg::new("verbose").long("verbose").group("mode"))
+        .group(ArgGroup::new("mode"))
         .get_matches_from(vec!["prog", "--debug"]);
     assert!(m.is_present("mode"));
 }
diff --git a/tests/help.rs b/tests/help.rs
index 1b1bc5601f7..20f340eb68b 100644
--- a/tests/help.rs
+++ b/tests/help.rs
@@ -35,7 +35,7 @@ FLAGS:
     -V, --version    Prints version information
 
 OPTIONS:
-    -O, --Option <option3>           specific vals [possible values: fast, slow]
+    -O, --Option3 <option3>          specific vals [possible values: fast, slow]
         --long-option-2 <option2>    tests long options with exclusions
         --maxvals3 <maxvals>...      Tests 3 max vals
         --minvals2 <minvals>...      Tests 2 min vals
diff --git a/tests/possible_values.rs b/tests/possible_values.rs
index 9583b3f2276..a89f2f7f21b 100644
--- a/tests/possible_values.rs
+++ b/tests/possible_values.rs
@@ -3,22 +3,22 @@ mod utils;
 use clap::{App, Arg, ErrorKind};
 
 #[cfg(feature = "suggestions")]
-static PV_ERROR: &str = "error: 'slo' isn't a valid value for '--Option <option3>'
+static PV_ERROR: &str = "error: 'slo' isn't a valid value for '--Option3 <option3>'
 \t[possible values: fast, slow]
 
 \tDid you mean 'slow'?
 
 USAGE:
-    clap-test --Option <option3>
+    clap-test --Option3 <option3>
 
 For more information try --help";
 
 #[cfg(not(feature = "suggestions"))]
-static PV_ERROR: &'static str = "error: 'slo' isn't a valid value for '--Option <option3>'
+static PV_ERROR: &'static str = "error: 'slo' isn't a valid value for '--Option3 <option3>'
 \t[possible values: fast, slow]
 
 USAGE:
-    clap-test --Option <option3>
+    clap-test --Option3 <option3>
 
 For more information try --help";
 
diff --git a/tests/utils.rs b/tests/utils.rs
index 5c0f96c2a5b..15d728359ad 100644
--- a/tests/utils.rs
+++ b/tests/utils.rs
@@ -85,7 +85,7 @@ pub fn complex_app() -> App<'static> {
                 .conflicts_with("option")
                 .requires("positional2"),
             Arg::from("[positional2] 'tests positionals with exclusions'"),
-            Arg::from("-O --Option [option3] 'specific vals'").possible_values(&opt3_vals),
+            Arg::from("-O --Option3 [option3] 'specific vals'").possible_values(&opt3_vals),
             Arg::from("[positional3]... 'tests specific values'").possible_values(&pos3_vals),
             Arg::from("--multvals [one] [two] 'Tests mutliple values, not mult occs'"),
             Arg::from("--multvalsmo... [one] [two] 'Tests mutliple values, and mult occs'"),