Create printer pkg, fix color force enable/disable

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

cmd/kubectx/delete.go

@@ -6,6 +6,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
 // DeleteOp indicates intention to delete contexts.
@@ -23,10 +24,10 @@ func (op DeleteOp) Run(_, stderr io.Writer) error {
 		}
 		if wasActiveContext {
 			// TODO we don't always run as kubectx (sometimes "kubectl ctx")
-			printWarning(stderr, "You deleted the current context. use \"kubectx\" to select a different one.")
+			printer.Warning(stderr, "You deleted the current context. use \"kubectx\" to select a different one.")
 		}
 
-		printSuccess(stderr, "deleted context %q", deletedName)
+		printer.Success(stderr, "deleted context %q", deletedName)
 	}
 	return nil
 }

cmd/kubectx/env.go

@@ -1,29 +1,2 @@
 package main
 
-import "os"
-
-const (
-	// EnvFZFIgnore describes the environment variable to set to disable
-	// interactive context selection when fzf is installed.
-	EnvFZFIgnore = "KUBECTX_IGNORE_FZF"
-
-	// EnvForceColor describes the environment variable to disable color usage
-	// when printing current context in a list.
-	EnvNoColor = `NO_COLOR`
-
-	// EnvForceColor describes the "internal" environment variable to force
-	// color usage to show current context in a list.
-	EnvForceColor = `_KUBECTX_FORCE_COLOR`
-
-	// EnvDebug describes the internal environment variable for more verbose logging.
-	EnvDebug = `DEBUG`
-)
-
-func useColors() bool {
-	if os.Getenv(EnvForceColor) != "" {
-		return true
-	} else if os.Getenv(EnvNoColor) != "" {
-		return false
-	}
-	return true
-}

cmd/kubectx/flags.go

@@ -7,10 +7,6 @@ import (
 	"strings"
 )
 
-type Op interface {
-	Run(stdout, stderr io.Writer) error
-}
-
 // UnsupportedOp indicates an unsupported flag.
 type UnsupportedOp struct{ Err error }
 

cmd/kubectx/fzf.go

@@ -11,6 +11,9 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/mattn/go-isatty"
+
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
 type InteractiveSwitchOp struct {
@@ -26,7 +29,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 
 	cmd.Env = append(os.Environ(),
 		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
-		fmt.Sprintf("%s=1", EnvForceColor))
+		fmt.Sprintf("%s=1", env.EnvForceColor))
 	if err := cmd.Run(); err != nil {
 		if _, ok := err.(*exec.ExitError); !ok {
 			return err
@@ -40,7 +43,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to switch context")
 	}
-	printSuccess(stderr, "Switched to context %q.", name)
+	printer.Success(stderr, "Switched to context %q.", name)
 	return nil
 }
 
@@ -60,6 +63,6 @@ func fzfInstalled() bool {
 
 // isInteractiveMode determines if we can do choosing with fzf.
 func isInteractiveMode(stdout *os.File) bool {
-	v := os.Getenv(EnvFZFIgnore)
+	v := os.Getenv(env.EnvFZFIgnore)
 	return v == "" && isTerminal(stdout) && fzfInstalled()
 }

cmd/kubectx/kubeconfig_test.go

@@ -8,6 +8,22 @@ import (
 	"testing"
 )
 
+
+func withTestVar(key, value string) func() {
+	// TODO(ahmetb) this method is currently duplicated
+	// consider extracting to internal/testutil or something
+
+	orig, ok := os.LookupEnv(key)
+	os.Setenv(key, value)
+	return func() {
+		if ok {
+			os.Setenv(key, orig)
+		} else {
+			os.Unsetenv(key)
+		}
+	}
+}
+
 func Test_homeDir(t *testing.T) {
 	type env struct{ k, v string }
 	cases := []struct {

cmd/kubectx/list.go

@@ -9,6 +9,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
 // ListOp describes listing contexts.
@@ -28,9 +29,9 @@ func (_ ListOp) Run(stdout, _ io.Writer) error {
 	// TODO support KUBECTX_CURRENT_BGCOLOR
 
 	currentColor := color.New(color.FgGreen, color.Bold)
-	if useColors() {
+	if v := printer.UseColors(); v != nil && *v {
 		currentColor.EnableColor()
-	} else {
+	} else if v != nil && !*v {
 		currentColor.DisableColor()
 	}
 

cmd/kubectx/main.go

@@ -5,15 +5,20 @@ import (
 	"io"
 	"os"
 
-	"github.com/fatih/color"
+	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
+type Op interface {
+	Run(stdout, stderr io.Writer) error
+}
+
 func main() {
 	op := parseArgs(os.Args[1:])
 	if err := op.Run(os.Stdout, os.Stderr); err != nil {
-		printError(os.Stderr, err.Error())
+		printer.Error(os.Stderr, err.Error())
 
-		if _, ok := os.LookupEnv(EnvDebug); ok {
+		if _, ok := os.LookupEnv(env.EnvDebug); ok {
 			// print stack trace in verbose mode
 			fmt.Fprintf(os.Stderr, "[DEBUG] error: %+v\n", err)
 		}
@@ -21,14 +26,3 @@ func main() {
 	}
 }
 
-func printError(w io.Writer, format string, args ...interface{}) {
-	fmt.Fprintf(w, color.RedString("error: ")+format+"\n", args...)
-}
-
-func printWarning(w io.Writer, format string, args ...interface{}) {
-	fmt.Fprintf(w, color.YellowString("warning: ")+format+"\n", args...)
-}
-
-func printSuccess(w io.Writer, format string, args ...interface{}) {
-	fmt.Fprintf(w, color.GreenString(fmt.Sprintf(format+"\n", args...)))
-}

cmd/kubectx/rename.go

@@ -7,6 +7,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
 // RenameOp indicates intention to rename contexts.
@@ -49,7 +50,7 @@ func (op RenameOp) Run(_, stderr io.Writer) error {
 	}
 
 	if kc.ContextExists(op.New) {
-		printWarning(stderr, "context %q exists, overwriting it.", op.New)
+		printer.Warning(stderr, "context %q exists, overwriting it.", op.New)
 		if err := kc.DeleteContextEntry(op.New); err != nil {
 			return errors.Wrap(err, "failed to delete new context to overwrite it")
 		}
@@ -66,6 +67,6 @@ func (op RenameOp) Run(_, stderr io.Writer) error {
 	if err := kc.Save(); err != nil {
 		return errors.Wrap(err, "failed to save modified kubeconfig")
 	}
-	printSuccess(stderr, "Context %q renamed to %q.", op.Old, op.New)
+	printer.Success(stderr, "Context %q renamed to %q.", op.Old, op.New)
 	return nil
 }

cmd/kubectx/switch.go

@@ -6,6 +6,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
+	"github.com/ahmetb/kubectx/internal/printer"
 )
 
 // SwitchOp indicates intention to switch contexts.
@@ -24,7 +25,7 @@ func (op SwitchOp) Run(_, stderr io.Writer) error {
 	if err != nil {
 		return errors.Wrap(err, "failed to switch context")
 	}
-	printSuccess(stderr, "Switched to context %q.", newCtx)
+	printer.Success(stderr, "Switched to context %q.", newCtx)
 	return nil
 }
 

internal/env/constants.go

@@ -0,0 +1,19 @@
+package env
+
+const (
+	// EnvFZFIgnore describes the environment variable to set to disable
+	// interactive context selection when fzf is installed.
+	EnvFZFIgnore = "KUBECTX_IGNORE_FZF"
+
+	// EnvForceColor describes the environment variable to disable color usage
+	// when printing current context in a list.
+	EnvNoColor = `NO_COLOR`
+
+	// EnvForceColor describes the "internal" environment variable to force
+	// color usage to show current context in a list.
+	EnvForceColor = `_KUBECTX_FORCE_COLOR`
+
+	// EnvDebug describes the internal environment variable for more verbose logging.
+	EnvDebug = `DEBUG`
+)
+

internal/printer/color.go

@@ -0,0 +1,20 @@
+package printer
+
+import (
+	"os"
+
+	"github.com/ahmetb/kubectx/internal/env"
+)
+
+// UseColors returns true if colors are force-enabled,
+// false if colors are disabled, or nil for default behavior
+// which is determined based on factors like if stdout is tty.
+func UseColors() *bool {
+	tr, fa := true, false
+	if os.Getenv(env.EnvForceColor) != "" {
+		return &tr
+	} else if os.Getenv(env.EnvNoColor) != "" {
+		return &fa
+	}
+	return nil
+}

internal/printer/color_test.go

@@ -1,8 +1,10 @@
-package main
+package printer
 
 import (
 	"os"
 	"testing"
+
+	"github.com/google/go-cmp/cmp"
 )
 
 func withTestVar(key, value string) func() {
@@ -17,20 +19,24 @@ func withTestVar(key, value string) func() {
 	}
 }
 
+var (
+	tr, fa = true, false
+)
+
 func Test_useColors_forceColors(t *testing.T) {
 	defer withTestVar("_KUBECTX_FORCE_COLOR", "1")()
 	defer withTestVar("NO_COLOR", "1")()
 
-	if !useColors() {
-		t.Fatal("expected useColors() = true")
+	if v := UseColors(); !cmp.Equal(v, &tr) {
+		t.Fatalf("expected UseColors() = true; got = %v", v)
 	}
 }
 
 func Test_useColors_disableColors(t *testing.T) {
 	defer withTestVar("NO_COLOR", "1")()
 
-	if useColors() {
-		t.Fatal("expected useColors() = false")
+	if v := UseColors(); !cmp.Equal(v, &fa) {
+		t.Fatalf("expected UseColors() = false; got = %v", v)
 	}
 }
 
@@ -38,7 +44,7 @@ func Test_useColors_default(t *testing.T) {
 	defer withTestVar("NO_COLOR", "")()
 	defer withTestVar("_KUBECTX_FORCE_COLOR", "")()
 
-	if !useColors() {
-		t.Fatal("expected useColors() = true")
+	if v := UseColors(); v != nil {
+		t.Fatalf("expected UseColors() = nil; got=%v", *v)
 	}
 }

internal/printer/printer.go

@@ -0,0 +1,42 @@
+package printer
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/fatih/color"
+)
+
+var (
+	errorColor   = color.New(color.FgRed, color.Bold)
+	warningColor = color.New(color.FgYellow, color.Bold)
+	successColor = color.New(color.FgGreen)
+)
+
+func init() {
+	colors := UseColors()
+	if colors == nil {
+		return
+	}
+	if *colors {
+		errorColor.EnableColor()
+		warningColor.EnableColor()
+		successColor.EnableColor()
+	} else {
+		errorColor.DisableColor()
+		warningColor.DisableColor()
+		successColor.DisableColor()
+	}
+}
+
+func Error(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.RedString("error: ")+format+"\n", args...)
+}
+
+func Warning(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.YellowString("warning: ")+format+"\n", args...)
+}
+
+func Success(w io.Writer, format string, args ...interface{}) {
+	fmt.Fprintf(w, color.GreenString(fmt.Sprintf(format+"\n", args...)))
+}