Color output should be to a colorable writer

commands/config_install.go

@@ -96,16 +96,15 @@ func runConfigInstall(cmd *cobra.Command, args []string) error {
 		}
 	}()
 
-	cmd.PrintErrln()
-	cmd.PrintErrf(
-		"The following files have been created:\n"+
+	printColorable(
+		cmd.ErrOrStderr(),
+		"\nThe following files have been created:\n"+
 			"  - Configuration: %s\n"+
-			"  - Executable: %s\n",
+			"  - Executable: %s\n\n"+
+			"The configuration file will be auto-updated periodically in the background.\n",
 		color.CyanString(replaceHomeDir(configFilePath)),
 		color.CyanString(replaceHomeDir(binFilePath)),
 	)
-	cmd.PrintErrln()
-	cmd.PrintErrln("The configuration file will be auto-updated periodically in the background.")
 
 	isInPath, err := alt.InPath(binDir)
 	if err != nil {
@@ -120,16 +119,18 @@ func runConfigInstall(cmd *cobra.Command, args []string) error {
 	cmd.PrintErrln()
 
 	if isInPath {
-		cmd.PrintErrln("Run the new executable with:", color.GreenString(filepath.Base(binFilePath)))
+		printColorable(cmd.ErrOrStderr(), "Run the new executable with: %s\n", color.GreenString(filepath.Base(binFilePath)))
 	} else {
-		cmd.PrintErrf(
+		printColorable(
+			cmd.ErrOrStderr(),
 			"Add the following directory to your %s: %s\n",
 			envVarName,
 			color.YellowString(replaceHomeDir(binDir)),
 		)
 		cmd.PrintErrln()
-		cmd.PrintErrln(
-			"Then you will be able to run the new executable with:",
+		printColorable(
+			cmd.ErrOrStderr(),
+			"Then you will be able to run the new executable with: %s\n",
 			color.YellowString(filepath.Base(binFilePath)),
 		)
 	}

commands/root.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/fatih/color"
+	"github.com/mattn/go-colorable"
 	"github.com/platformsh/platformify/commands"
 	"github.com/platformsh/platformify/vendorization"
 	"github.com/spf13/cobra"
@@ -88,13 +89,13 @@ func newRootCommand(cnf *config.Config, assets *vendorization.VendorAssets) *cob
 				Stdin:              cmd.InOrStdin(),
 			}
 			if err := c.Init(); err != nil {
-				_, _ = fmt.Fprint(color.Error, color.RedString(err.Error()))
+				printColorable(cmd.ErrOrStderr(), color.RedString(err.Error()))
 				os.Exit(1)
 				return
 			}
 
 			if err := c.Exec(cmd.Context(), os.Args[1:]...); err != nil {
-				_, _ = fmt.Fprint(color.Error, color.RedString(err.Error()))
+				printColorable(cmd.ErrOrStderr(), color.RedString(err.Error()))
 				exitCode := 1
 				var execErr *exec.ExitError
 				if errors.As(err, &execErr) {
@@ -103,11 +104,11 @@ func newRootCommand(cnf *config.Config, assets *vendorization.VendorAssets) *cob
 				os.Exit(exitCode)
 			}
 		},
-		PersistentPostRun: func(_ *cobra.Command, _ []string) {
-			checkShellConfigLeftovers(cnf)
+		PersistentPostRun: func(cmd *cobra.Command, _ []string) {
+			checkShellConfigLeftovers(cnf, cmd.ErrOrStderr())
 			select {
 			case rel := <-updateMessageChan:
-				printUpdateMessage(rel, cnf)
+				printUpdateMessage(rel, cnf, cmd.ErrOrStderr())
 			default:
 			}
 		},
@@ -169,7 +170,7 @@ func newRootCommand(cnf *config.Config, assets *vendorization.VendorAssets) *cob
 }
 
 // checkShellConfigLeftovers checks .zshrc and .bashrc for any leftovers from the legacy CLI
-func checkShellConfigLeftovers(cnf *config.Config) {
+func checkShellConfigLeftovers(cnf *config.Config, stdErr io.Writer) {
 	start := fmt.Sprintf("# BEGIN SNIPPET: %s configuration", cnf.Application.Name)
 	end := "# END SNIPPET"
 	shellConfigSnippet := regexp.MustCompile(regexp.QuoteMeta(start) + "(?s).+?" + regexp.QuoteMeta(end))
@@ -195,44 +196,42 @@ func checkShellConfigLeftovers(cnf *config.Config) {
 		}
 
 		if shellConfigSnippet.Match(shellConfig) {
-			fmt.Fprintf(color.Error, "%s Your %s file contains code that is no longer needed for the New %s\n",
+			printColorable(stdErr, "%s Your %s file contains code that is no longer needed for the New %s\n",
 				color.YellowString("Warning:"),
 				shellConfigFile,
 				cnf.Application.Name,
 			)
-			fmt.Fprintf(color.Error, "%s %s\n", color.YellowString("Please remove the following lines from:"), shellConfigFile)
-			fmt.Fprintf(color.Error, "\t%s\n", strings.ReplaceAll(string(shellConfigSnippet.Find(shellConfig)), "\n", "\n\t"))
+			printColorable(stdErr, "%s %s\n", color.YellowString("Please remove the following lines from:"), shellConfigFile)
+			printColorable(stdErr, "\t%s\n", strings.ReplaceAll(string(shellConfigSnippet.Find(shellConfig)), "\n", "\n\t"))
 		}
 	}
 }
 
-func printUpdateMessage(newRelease *internal.ReleaseInfo, cnf *config.Config) {
+func printUpdateMessage(newRelease *internal.ReleaseInfo, cnf *config.Config, stdErr io.Writer) {
 	if newRelease == nil {
 		return
 	}
 
-	fmt.Fprintf(color.Error, "\n\n%s %s → %s\n",
+	printColorable(stdErr, "\n\n%s %s → %s\n",
 		color.YellowString(fmt.Sprintf("A new release of the %s is available:", cnf.Application.Name)),
 		color.CyanString(config.Version),
 		color.CyanString(newRelease.Version),
 	)
 
 	executable, err := os.Executable()
 	if err == nil && cnf.Wrapper.HomebrewTap != "" && isUnderHomebrew(executable) {
-		fmt.Fprintf(
-			color.Error,
+		printColorable(stdErr,
 			"To upgrade, run: brew update && brew upgrade %s\n",
 			color.YellowString(cnf.Wrapper.HomebrewTap),
 		)
 	} else if cnf.Wrapper.GitHubRepo != "" {
-		fmt.Fprintf(
-			color.Error,
+		printColorable(stdErr,
 			"To upgrade, follow the instructions at: https://github.com/%s#upgrade\n",
 			cnf.Wrapper.GitHubRepo,
 		)
 	}
 
-	fmt.Fprintf(color.Error, "%s\n\n", color.YellowString(newRelease.URL))
+	printColorable(stdErr, "%s\n\n", color.YellowString(newRelease.URL))
 }
 
 func isUnderHomebrew(binary string) bool {
@@ -258,3 +257,10 @@ func debugLog(format string, v ...any) {
 	prefix := color.New(color.ReverseVideo).Sprintf("DEBUG")
 	_, _ = fmt.Fprintf(color.Error, prefix+" "+strings.TrimSpace(format)+"\n", v...)
 }
+
+func printColorable(w io.Writer, format string, a ...any) {
+	if se, ok := w.(*os.File); ok {
+		w = colorable.NewColorable(se)
+	}
+	_, _ = fmt.Fprintf(w, format, a...)
+}