implement short -v version flag (issue #654)

cobra.go

@@ -51,7 +51,7 @@ var EnableCommandSorting = true
 // if the CLI is started from explorer.exe.
 // To disable the mousetrap, just set this variable to blank string ("").
 // Works only on Microsoft Windows.
-var MousetrapHelpText string = `This is a command line tool.
+var MousetrapHelpText = `This is a command line tool.
 
 You need to open cmd.exe and run it from there.
 `

command.go

@@ -932,7 +932,7 @@ func (c *Command) InitDefaultVersionFlag() {
 		} else {
 			usage += c.Name()
 		}
-		c.Flags().Bool("version", false, usage)
+		c.Flags().BoolP("version", "v", false, usage)
 	}
 }
 

command_test.go

@@ -854,6 +854,16 @@ func TestVersionFlagExecuted(t *testing.T) {
 	checkStringContains(t, output, "root version 1.0.0")
 }
 
+func TestShortVersionFlagExecuted(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}
+
+	output, err := executeCommand(rootCmd, "-v", "arg1")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	checkStringContains(t, output, "root version 1.0.0")
+}
+
 func TestVersionTemplate(t *testing.T) {
 	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}
 	rootCmd.SetVersionTemplate(`customized version: {{.Version}}`)
@@ -866,6 +876,18 @@ func TestVersionTemplate(t *testing.T) {
 	checkStringContains(t, output, "customized version: 1.0.0")
 }
 
+func TestShortVersionTemplate(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}
+	rootCmd.SetVersionTemplate(`customized version: {{.Version}}`)
+
+	output, err := executeCommand(rootCmd, "-v", "arg1")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, "customized version: 1.0.0")
+}
+
 func TestVersionFlagExecutedOnSubcommand(t *testing.T) {
 	rootCmd := &Command{Use: "root", Version: "1.0.0"}
 	rootCmd.AddCommand(&Command{Use: "sub", Run: emptyRun})
@@ -886,20 +908,47 @@ func TestVersionFlagOnlyAddedToRoot(t *testing.T) {
 	if err == nil {
 		t.Errorf("Expected error")
 	}
-
 	checkStringContains(t, err.Error(), "unknown flag: --version")
 }
 
+func TestShortVersionFlagOnlyAddedToRoot(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}
+	rootCmd.AddCommand(&Command{Use: "sub", Run: emptyRun})
+	_, err := executeCommand(rootCmd, "sub", "-v")
+	if err == nil {
+		t.Errorf("Expected error")
+	}
+	checkStringContains(t, err.Error(), "unknown shorthand flag: 'v' in -v")
+}
+
 func TestVersionFlagOnlyExistsIfVersionNonEmpty(t *testing.T) {
 	rootCmd := &Command{Use: "root", Run: emptyRun}
-
 	_, err := executeCommand(rootCmd, "--version")
 	if err == nil {
 		t.Errorf("Expected error")
 	}
 	checkStringContains(t, err.Error(), "unknown flag: --version")
 }
 
+func TestShortVersionFlagOnlyExistsIfVersionNonEmpty(t *testing.T) {
+	rootCmd := &Command{Use: "root", Run: emptyRun}
+	_, err := executeCommand(rootCmd, "-v")
+	if err == nil {
+		t.Errorf("Expected error")
+	}
+	checkStringContains(t, err.Error(), "unknown shorthand flag: 'v' in -v")
+}
+
+func TestShortVersionAndLongVersion(t *testing.T) {
+	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}
+	output, err := executeCommand(rootCmd, "-v", "--version")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	checkStringContains(t, output, "root version 1.0.0")
+}
+
 func TestUsageIsNotPrintedTwice(t *testing.T) {
 	var cmd = &Command{Use: "root"}
 	var sub = &Command{Use: "sub"}