Function colorSupported

app/cli/cmd/color.go:65–91

colorSupported decides whether ANSI color should be emitted, given a way to look up environment variables and whether stderr is an interactive terminal. It is kept pure so the decision logic can be unit tested. Precedence: 1. NO_COLOR set, any value -> no color (https://no-color.org/). Universal op

(lookupEnv func(string) (string, bool), isTerminal bool)

//     render ANSI (see colorCapableCISignals); otherwise no color. This keeps
//     piped output and ANSI-incapable consoles (e.g. Jenkins) clean.
func colorSupported(lookupEnv func(string) (string, bool), isTerminal bool) bool {
	if _, ok := lookupEnv("NO_COLOR"); ok {
		return false
	}

	for _, key := range []string{"CLICOLOR_FORCE", "FORCE_COLOR"} {
		if v, ok := lookupEnv(key); ok && v != "" && v != "0" {
			return true
		}
	}

	if v, ok := lookupEnv("TERM"); ok && v == "dumb" {
		return false
	}

	if isTerminal {
		return true
	}

	for _, key := range colorCapableCISignals {
		if _, ok := lookupEnv(key); ok {
			return true
		}
	}

	return false
}