add colors to CLI commands

command.go

@@ -31,6 +31,34 @@ import (
 // FParseErrWhitelist configures Flag parse errors to be ignored
 type FParseErrWhitelist flag.ParseErrorsWhitelist
 
+// TerminalColor is a type used for the names of the different
+// colors in the terminal
+type TerminalColor int
+
+// Colors represents the different colors one can use in the terminal
+const (
+	ColorBlack TerminalColor = iota + 30
+	ColorRed
+	ColorGreen
+	ColorYellow
+	ColorBlue
+	ColorMagenta
+	ColorCyan
+	ColorLightGray
+)
+
+// This sequence starts at 90, so we reset iota
+const (
+	ColorDarkGray TerminalColor = iota + 90
+	ColorLightRed
+	ColorLightGreen
+	ColorLightYellow
+	ColorLightBlue
+	ColorLightMagenta
+	ColorLightCyan
+	ColorWhite
+)
+
 // Command is just that, a command for your application.
 // E.g.  'go run ...' - 'run' is the command. Cobra requires
 // you to define the usage and description as part of your command
@@ -47,6 +75,12 @@ type Command struct {
 	// Example: add [-F file | -D dir]... [-f format] profile
 	Use string
 
+	// DisableColors is a boolean used to disable the coloring in the command line
+	DisableColors bool
+
+	// Color represents the color to use to print the command in the terminal
+	Color TerminalColor
+
 	// Aliases is an array of aliases that can be used instead of the first word in Use.
 	Aliases []string
 
@@ -467,10 +501,18 @@ var minNamePadding = 11
 
 // NamePadding returns padding for the name.
 func (c *Command) NamePadding() int {
+	additionalPadding := c.additionalNamePadding()
 	if c.parent == nil || minNamePadding > c.parent.commandsMaxNameLen {
-		return minNamePadding
+		return minNamePadding + additionalPadding
 	}
-	return c.parent.commandsMaxNameLen
+	return c.parent.commandsMaxNameLen + additionalPadding
+}
+
+func (c *Command) additionalNamePadding() int {
+	// additionalPadding is used to pad non visible characters
+	// This happens for example when using colors, where \033[31m isn't seen
+	// but still is counted towards the padding
+	return len(c.ColoredName()) - len(c.Name())
 }
 
 // UsageTemplate returns usage template for the command.
@@ -493,7 +535,7 @@ Examples:
 {{.Example}}{{end}}{{if .HasAvailableSubCommands}}
 
 Available Commands:{{range .Commands}}{{if (or .IsAvailableCommand (eq .Name "help"))}}
-  {{rpad .Name .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableLocalFlags}}
+  {{rpad .ColoredName .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{if .HasAvailableLocalFlags}}
 
 Flags:
 {{.LocalFlags.FlagUsages | trimTrailingWhitespaces}}{{end}}{{if .HasAvailableInheritedFlags}}
@@ -1293,6 +1335,25 @@ func (c *Command) Name() string {
 	return name
 }
 
+// isColoringEnabled will be queried to know whether or not we should enable
+// the coloring on a command. This will usually be called on the Root command
+// and applied for every command.
+func (c *Command) isColoringEnabled() bool {
+	_, noColorEnv := os.LookupEnv("NO_COLOR")
+	if c.DisableColors || noColorEnv {
+		return false
+	}
+	return true
+}
+
+// ColoredName returns the command's Name in the correct color if specified
+func (c *Command) ColoredName() string {
+	if c.Color != 0 && c.Root().isColoringEnabled() {
+		return fmt.Sprintf("\033[%dm%s\033[0m", c.Color, c.Name())
+	}
+	return c.Name()
+}
+
 // HasAlias determines if a given string is an alias of the command.
 func (c *Command) HasAlias(s string) bool {
 	for _, a := range c.Aliases {

command_test.go

@@ -3,6 +3,7 @@ package cobra
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
@@ -1989,3 +1990,76 @@ func TestFParseErrWhitelistSiblingCommand(t *testing.T) {
 	}
 	checkStringContains(t, output, "unknown flag: --unknown")
 }
+
+func commandIsColoredRed(c *Command) error {
+	if c.Name() != "cmd" {
+		return fmt.Errorf("Unexpected name with Colored Command: %s", c.Name())
+	}
+	// If a color is specified, the ColoredName and the Name should be different
+	if c.Name() == c.ColoredName() {
+		return errors.New("Name and ColoredName should not give the same result")
+	}
+	if c.ColoredName() != "\033[31m"+c.Name()+"\033[0m" {
+		return errors.New("ColoredName should only add color to the name")
+	}
+	if c.additionalNamePadding() == 0 {
+		return errors.New("With a color, the additionalNamePadding should be more than 0")
+	}
+	return nil
+}
+
+func commandIsNotColored(c *Command) error {
+	if c.Name() != "cmd" {
+		return errors.New("Unexpected name with simple Command")
+	}
+	// If no color is specified, the ColoredName should equal the Name
+	if c.Name() != c.ColoredName() {
+		return errors.New("Name and ColoredName should give the same result")
+	}
+	if c.additionalNamePadding() != 0 {
+		return errors.New("With no color, the additionalNamePadding should be 0")
+	}
+	return nil
+}
+
+func TestColoredName(t *testing.T) {
+	c := &Command{
+		Use: "cmd",
+	}
+	err := commandIsNotColored(c)
+	if err != nil {
+		t.Error(err)
+	}
+	c = &Command{
+		Use:   "cmd",
+		Color: ColorRed,
+	}
+	err = commandIsColoredRed(c)
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestColoredNameWithNoColorSetup(t *testing.T) {
+	c := &Command{
+		Use:   "cmd",
+		Color: ColorRed,
+	}
+	err := commandIsColoredRed(c)
+	if err != nil {
+		t.Error(err)
+	}
+
+	os.Setenv("NO_COLOR", "true")
+	err = commandIsNotColored(c)
+	if err != nil {
+		t.Error(err)
+	}
+	os.Unsetenv("NO_COLOR")
+
+	c.DisableColors = true
+	err = commandIsNotColored(c)
+	if err != nil {
+		t.Error(err)
+	}
+}