Add '--version' flag to Help output (#1707)

command.go

@@ -1123,7 +1123,8 @@ Simply type ` + c.Name() + ` help [path to command] for full details.`,
 					c.Printf("Unknown help topic %#q\n", args)
 					CheckErr(c.Root().Usage())
 				} else {
-					cmd.InitDefaultHelpFlag() // make possible 'help' flag to be shown
+					cmd.InitDefaultHelpFlag()    // make possible 'help' flag to be shown
+					cmd.InitDefaultVersionFlag() // make possible 'version' flag to be shown
 					CheckErr(cmd.Help())
 				}
 			},

command_test.go

@@ -2343,3 +2343,90 @@ func TestSetContextPersistentPreRun(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+const VersionFlag = "--version"
+const HelpFlag = "--help"
+
+func TestNoRootRunCommandExecutedWithVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Long: "Long description"}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringContains(t, output, VersionFlag)
+}
+
+func TestNoRootRunCommandExecutedWithoutVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Long: "Long description"}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringOmits(t, output, VersionFlag)
+}
+
+func TestHelpCommandExecutedWithVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Long: "Long description", Run: emptyRun}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd, "help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringContains(t, output, VersionFlag)
+}
+
+func TestHelpCommandExecutedWithoutVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Long: "Long description", Run: emptyRun}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd, "help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringOmits(t, output, VersionFlag)
+}
+
+func TestHelpflagCommandExecutedWithVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Long: "Long description", Run: emptyRun}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd, HelpFlag)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringContains(t, output, VersionFlag)
+}
+
+func TestHelpflagCommandExecutedWithoutVersionSet(t *testing.T) {
+	rootCmd := &Command{Use: "root", Long: "Long description", Run: emptyRun}
+	rootCmd.AddCommand(&Command{Use: "child", Run: emptyRun})
+
+	output, err := executeCommand(rootCmd, HelpFlag)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, rootCmd.Long)
+	checkStringContains(t, output, HelpFlag)
+	checkStringOmits(t, output, VersionFlag)
+}