feat: Add info about optional flags to usage (#416)

help_test.go

@@ -51,7 +51,7 @@ func TestHelpOptionalArgs(t *testing.T) {
 		assert.NoError(t, err)
 	})
 	assert.True(t, exited)
-	expected := `Usage: test-app [<one> [<two>]]
+	expected := `Usage: test-app [<one> [<two>]] [flags]
 
 Arguments:
   [<one>]    One optional arg.
@@ -105,7 +105,7 @@ func TestHelp(t *testing.T) {
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app --required <command>
+		expected := `Usage: test-app --required <command> [flags]
 
 A test app.
 
@@ -120,13 +120,13 @@ Flags:
   -s, --[no-]sort            Is sortable or not.
 
 Commands:
-  one --required
+  one --required [flags]
     A subcommand.
 
-  two <three> --required --required-two --required-three
+  two <three> --required --required-two --required-three [flags]
     Sub-sub-arg.
 
-  two four --required --required-two
+  two four --required --required-two [flags]
     Sub-sub-command.
 
 Run "test-app <command> --help" for more information on a command.
@@ -144,7 +144,7 @@ Run "test-app <command> --help" for more information on a command.
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app two <three> --required --required-two --required-three
+		expected := `Usage: test-app two <three> --required --required-two --required-three [flags]
 
 Sub-sub-arg.
 
@@ -215,18 +215,18 @@ func TestFlagsLast(t *testing.T) {
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app --required <command>
+		expected := `Usage: test-app --required <command> [flags]
 
 A test app.
 
 Commands:
-  one --required
+  one --required [flags]
     A subcommand.
 
-  two <three> --required --required-two --required-three
+  two <three> --required --required-two --required-three [flags]
     Sub-sub-arg.
 
-  two four --required --required-two
+  two four --required --required-two [flags]
     Sub-sub-command.
 
 Flags:
@@ -253,7 +253,7 @@ Run "test-app <command> --help" for more information on a command.
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app two <three> --required --required-two --required-three
+		expected := `Usage: test-app two <three> --required --required-two --required-three [flags]
 
 Sub-sub-arg.
 
@@ -320,7 +320,7 @@ func TestHelpTree(t *testing.T) {
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app <command>
+		expected := `Usage: test-app <command> [flags]
 
 A test app.
 
@@ -353,7 +353,7 @@ Run "test-app <command> --help" for more information on a command.
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app one (un,uno) <command>
+		expected := `Usage: test-app one (un,uno) <command> [flags]
 
 subcommand one
 
@@ -414,7 +414,7 @@ func TestHelpCompactNoExpand(t *testing.T) {
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app <command>
+		expected := `Usage: test-app <command> [flags]
 
 A test app.
 
@@ -443,7 +443,7 @@ Run "test-app <command> --help" for more information on a command.
 			assert.NoError(t, err)
 		})
 		assert.True(t, exited)
-		expected := `Usage: test-app one (un,uno) <command>
+		expected := `Usage: test-app one (un,uno) <command> [flags]
 
 subcommand one
 
@@ -607,7 +607,7 @@ func TestAutoGroup(t *testing.T) {
 		}),
 	)
 	_, _ = app.Parse([]string{"--help", "two"})
-	assert.Equal(t, `Usage: test two
+	assert.Equal(t, `Usage: test two [flags]
 
 A non grouped subcommand.
 
@@ -691,7 +691,7 @@ func TestHelpGrouping(t *testing.T) {
 			assert.True(t, exited)
 			assert.NoError(t, err)
 		})
-		expected := `Usage: test-app <command>
+		expected := `Usage: test-app <command> [flags]
 
 A test app.
 
@@ -710,26 +710,26 @@ Group B
   --grouped-b-string=STRING    A string flag grouped in B.
 
 Commands:
-  two
+  two [flags]
     A non grouped subcommand.
 
 Group title taken from the kong.ExplicitGroups option
   A group header
 
-  one thing <arg>
+  one thing <arg> [flags]
     subcommand thing
 
-  one <other>
+  one <other> [flags]
     subcommand other
 
-  three
+  three [flags]
     Another subcommand grouped in A.
 
 Group B
-  one <stuff>
+  one <stuff> [flags]
     subcommand stuff
 
-  four
+  four [flags]
     Another subcommand grouped in B.
 
 Run "test-app <command> --help" for more information on a command.
@@ -747,7 +747,7 @@ Run "test-app <command> --help" for more information on a command.
 			assert.NoError(t, err)
 			assert.True(t, exited)
 		})
-		expected := `Usage: test-app two
+		expected := `Usage: test-app two [flags]
 
 A non grouped subcommand.
 
@@ -796,7 +796,7 @@ func TestUsageOnError(t *testing.T) {
 	_, err := p.Parse([]string{})
 	p.FatalIfErrorf(err)
 
-	expected := `Usage: test --flag=STRING
+	expected := `Usage: test --flag=STRING [flags]
 
 Some description.
 
@@ -824,7 +824,7 @@ func TestShortUsageOnError(t *testing.T) {
 	assert.Error(t, err)
 	p.FatalIfErrorf(err)
 
-	expected := `Usage: test --flag=STRING
+	expected := `Usage: test --flag=STRING [flags]
 Run "test --help" for more information.
 
 test: error: missing flags: --flag=STRING

helpwrap1.19_test.go

@@ -32,7 +32,7 @@ func TestCustomWrap(t *testing.T) {
 
 	_, err := app.Parse([]string{"--help"})
 	assert.NoError(t, err)
-	expected := `Usage: test-app
+	expected := `Usage: test-app [flags]
 
 A test app.
 

kong_test.go

@@ -1576,7 +1576,7 @@ func TestPassthroughCmdOnlyArgs(t *testing.T) {
 		} `cmd:"" passthrough:""`
 	}
 	_, err := kong.New(&cli)
-	assert.EqualError(t, err, "<anonymous struct>.Command: passthrough command command [<args> ...] must not have subcommands or flags")
+	assert.EqualError(t, err, "<anonymous struct>.Command: passthrough command command [<args> ...] [flags] must not have subcommands or flags")
 }
 
 func TestPassthroughCmdOnlyStringArgs(t *testing.T) {

model.go

@@ -162,6 +162,16 @@ func (n *Node) Summary() string {
 	} else if len(n.Children) > 0 {
 		summary += " <command>"
 	}
+	allFlags := n.Flags
+	if n.Parent != nil {
+		allFlags = append(allFlags, n.Parent.Flags...)
+	}
+	for _, flag := range allFlags {
+		if !flag.Required {
+			summary += " [flags]"
+			break
+		}
+	}
 	return summary
 }