define Run(stdout,stderr) method on **Ops

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

cmd/kubectx/current.go

@@ -7,7 +7,10 @@ import (
 	"github.com/pkg/errors"
 )
 
-func printCurrentContext(w io.Writer) error {
+// CurrentOp prints the current context
+type CurrentOp struct{}
+
+func (_op CurrentOp) Run(stdout, _ io.Writer) error {
 	cfgPath, err := kubeconfigPath()
 	if err != nil {
 		return errors.Wrap(err, "failed to determine kubeconfig path")
@@ -22,6 +25,6 @@ func printCurrentContext(w io.Writer) error {
 	if v == "" {
 		return errors.New("current-context is not set")
 	}
-	_, err = fmt.Fprintln(w, v)
+	_, err = fmt.Fprintln(stdout, v)
 	return err
 }

cmd/kubectx/delete.go

@@ -8,9 +8,14 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+// DeleteOp indicates intention to delete contexts.
+type DeleteOp struct {
+	Contexts []string // NAME or '.' to indicate current-context.
+}
+
 // deleteContexts deletes context entries one by one.
-func deleteContexts(w io.Writer, ctxs []string) error {
+func (op DeleteOp) Run(_, stderr io.Writer) error {
-	for _, ctx := range ctxs {
+	for _, ctx := range op.Contexts {
 		// TODO inefficency here. we open/write/close the same file many times.
 		deletedName, wasActiveContext, err := deleteContext(ctx)
 		if err != nil {
@@ -20,7 +25,7 @@ func deleteContexts(w io.Writer, ctxs []string) error {
 			// TODO we don't always run as kubectx (sometimes "kubectl ctx")
 			printWarning("You deleted the current context. use \"kubectx\" to select a different one.")
 		}
-		fmt.Fprintf(w, "deleted context %q\n", deletedName) // TODO write with printSuccess (i.e. green)
+		fmt.Fprintf(stderr, "deleted context %q\n", deletedName) // TODO write with printSuccess (i.e. green)
 	}
 	return nil
 }
@@ -49,10 +54,6 @@ func deleteContext(name string) (deleteName string, wasActiveContext bool, err e
 	if err := modifyDocToDeleteContext(rootNode, name); err != nil {
 		return "", false, errors.Wrap(err, "failed to modify yaml doc")
 	}
-
-	if err := resetFile(f); err != nil {
-		return "", false, err
-	}
 	return name, wasActiveContext, errors.Wrap(saveKubeconfigRaw(f, rootNode), "failed to save kubeconfig file")
 }
 

cmd/kubectx/flags.go

@@ -1,40 +1,23 @@
 package main
 
-import "strings"
+import (
+	"io"
+	"strings"
 
-type Op interface{}
+	"github.com/pkg/errors"
+)
 
-// HelpOp describes printing help.
+type Op interface {
-type HelpOp struct{}
+	Run(stdout, stderr io.Writer) error
-
-// ListOp describes listing contexts.
-type ListOp struct{}
-
-// CurrentOp prints the current context
-type CurrentOp struct{}
-
-// SwitchOp indicates intention to switch contexts.
-type SwitchOp struct {
-	Target string // '-' for back and forth, or NAME
 }
 
-// UnsetOp indicates intention to remove current-context preference.
+// UnsupportedOp indicates an unsupported flag.
-type UnsetOp struct{}
+type UnsupportedOp struct{ Err error }
 
-// DeleteOp indicates intention to delete contexts.
+func (op UnsupportedOp) Run(_, _ io.Writer) error {
-type DeleteOp struct {
+	return op.Err
-	Contexts []string // NAME or '.' to indicate current-context.
 }
 
-// RenameOp indicates intention to rename contexts.
-type RenameOp struct {
-	New string // NAME of New context
-	Old string // NAME of Old context (or '.' for current-context)
-}
-
-// UnknownOp indicates an unsupported flag.
-type UnknownOp struct{ Args []string }
-
 // parseArgs looks at flags (excl. executable name, i.e. argv[0])
 // and decides which operation should be taken.
 func parseArgs(argv []string) Op {
@@ -43,8 +26,7 @@ func parseArgs(argv []string) Op {
 	}
 
 	if argv[0] == "-d" {
-		ctxs := argv[1:]
+		return DeleteOp{Contexts: argv[1:]}
-		return DeleteOp{ctxs}
 	}
 
 	if len(argv) == 1 {
@@ -59,21 +41,16 @@ func parseArgs(argv []string) Op {
 			return UnsetOp{}
 		}
 
-		new, old, ok := parseRenameSyntax(v) // a=b a=.
+		if new, old, ok := parseRenameSyntax(v); ok {
-		if ok {
+			return RenameOp{New: new, Old: old}
-			return RenameOp{new, old}
 		}
 
 		if strings.HasPrefix(v, "-") && v != "-" {
-			return UnknownOp{argv}
+			return UnsupportedOp{Err: errors.Errorf("unsupported option %s", v)}
 		}
-
-		// TODO handle -d
-		// TODO handle -u/--unset
-		// TODO handle -c/--current
 		return SwitchOp{Target: argv[0]}
 	}
 
 	// TODO handle too many arguments e.g. "kubectx a b c"
-	return UnknownOp{}
+	return UnsupportedOp{Err: errors.New("too many arguments")}
 }

cmd/kubectx/flags_test.go

@@ -59,8 +59,8 @@ func Test_parseArgs_new(t *testing.T) {
 			want: RenameOp{"a", "."}},
 		{name: "unrecognized flag",
 			args: []string{"-x"},
-			want: UnknownOp{Args: []string{"-x"}}},
+			want: UnsupportedOp{Args: []string{"-x"}}},
-		// TODO add more UnknownOp cases
+		// TODO add more UnsupportedOp cases
 
 		// TODO consider these cases
 		// - kubectx foo --help

cmd/kubectx/help.go

@@ -5,7 +5,14 @@ import (
 	"io"
 )
 
-func printHelp(out io.Writer) {
+// HelpOp describes printing help.
+type HelpOp struct{}
+
+func (_ HelpOp) Run(stdout, _ io.Writer) error {
+	return printUsage(stdout)
+}
+
+func printUsage(out io.Writer) error {
 	help := `USAGE:
   kubectx                       : list the contexts
   kubectx <NAME>                : switch to context <NAME>
@@ -20,5 +27,6 @@ func printHelp(out io.Writer) {
 
   kubectx -h,--help             : show this message`
 
-	fmt.Fprintf(out, "%s\n", help)
+	_, err := fmt.Fprintf(out, "%s\n", help)
+	return err
 }

cmd/kubectx/kubeconfig.go

@@ -29,7 +29,10 @@ func kubeconfigPath() (string, error) {
 }
 
 func homeDir() string {
-	// TODO move tests out of kubeconfigPath to TestHomeDir()
+	// TODO move tests for this out of kubeconfigPath to TestHomeDir()
+	if v := os.Getenv("XDG_CACHE_HOME"); v != "" {
+		return v
+	}
 	home := os.Getenv("HOME")
 	if home == "" {
 		home = os.Getenv("USERPROFILE") // windows
@@ -37,6 +40,8 @@ func homeDir() string {
 	return home
 }
 
+
+// TODO parseKubeconfig doesn't seem necessary when there's a raw version that returns what's needed
 func parseKubeconfig(path string) (kubeconfig, error) {
 	// TODO refactor to accept io.Reader instead of file
 	var v kubeconfig

cmd/kubectx/kubeconfig_raw.go

@@ -17,6 +17,14 @@ func parseKubeconfigRaw(r io.Reader) (*yaml.Node, error) {
 }
 
 func saveKubeconfigRaw(w io.Writer, rootNode *yaml.Node) error {
+	if f, ok := w.(*os.File); ok {
+		if err := f.Truncate(0); err != nil {
+			return errors.Wrap(err, "failed to truncate")
+		}
+		if _, err := f.Seek(0, 0); err != nil {
+			return errors.Wrap(err, "failed to seek")
+		}
+	}
 	enc := yaml.NewEncoder(w)
 	enc.SetIndent(2)
 	return enc.Encode(rootNode)
@@ -39,14 +47,3 @@ func openKubeconfig() (f *os.File, rootNode *yaml.Node, err error) {
 	}
 	return f, kc, nil
 }
-
-// resetFile deletes contents of a file and sets the seek
-// position to 0.
-func resetFile(f *os.File) error {
-	if err := f.Truncate(0); err != nil {
-		return errors.Wrap(err, "failed to truncate")
-	}
-
-	_, err := f.Seek(0, 0)
-	return errors.Wrap(err, "failed to seek")
-}

cmd/kubectx/list.go

@@ -19,7 +19,10 @@ type kubeconfig struct {
 	Contexts       []context `yaml:"contexts"`
 }
 
-func printListContexts(out io.Writer) error {
+// ListOp describes listing contexts.
+type ListOp struct{}
+
+func (_ ListOp) Run(stdout, stderr io.Writer) error {
 	// TODO extract printing and sorting into a function that's testable
 
 	cfgPath, err := kubeconfigPath()
@@ -41,12 +44,11 @@ func printListContexts(out io.Writer) error {
 	// TODO support KUBECTX_CURRENT_FGCOLOR
 	// TODO support KUBECTX_CURRENT_BGCOLOR
 	for _, c := range ctxs {
-		out := c
+		s := c
 		if c == cfg.CurrentContext {
-			out = color.New(color.FgYellow, color.Bold).Sprint(c)
+			s = color.New(color.FgGreen, color.Bold).Sprint(c)
 		}
-		fmt.Println(out)
+		fmt.Fprintf(stdout, "%s\n", s)
 	}
 	return nil
 }
-

cmd/kubectx/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"fmt"
 	"os"
-	"strings"
 
 	"github.com/fatih/color"
 )
@@ -13,56 +12,9 @@ func main() {
 	var op Op
 	op = parseArgs(os.Args[1:])
 
-	// TODO consider addin Run() operation to each operation type
+	if err := op.Run(os.Stdout, os.Stderr); err != nil {
-	switch v := op.(type) {
+		printError(err.Error())
-	case HelpOp:
-		printHelp(os.Stdout)
-	case CurrentOp:
-		if err := printCurrentContext(os.Stdout); err != nil {
-			printError(err.Error())
-			os.Exit(1)
-		}
-	case UnsetOp:
-		if err := unsetContext(); err != nil {
-			printError(err.Error())
-			os.Exit(1)
-		}
-	case ListOp:
-		// TODO fzf installed show interactive selection
-
-		if err := printListContexts(os.Stdout); err != nil {
-			printError("%v", err)
-			os.Exit(1)
-		}
-	case DeleteOp:
-		if err := deleteContexts(os.Stderr, v.Contexts); err != nil {
-			printError("%v", err)
-			os.Exit(1)
-		}
-	case RenameOp:
-		if err := renameContexts(v.Old, v.New); err != nil {
-			printError("failed to rename: %v", err)
-			os.Exit(1)
-		}
-	case SwitchOp:
-		var newCtx string
-		var err error
-		if v.Target == "-" {
-			newCtx, err = swapContext()
-		} else {
-			newCtx, err = switchContext(v.Target)
-		}
-		if err != nil {
-			printError("failed to switch context: %v", err)
-			os.Exit(1)
-		}
-		fmt.Fprintf(os.Stderr, "Switched to context %q.\n", newCtx)
-	case UnknownOp:
-		printError("unsupported operation: %s", strings.Join(v.Args, " "))
-		printHelp(os.Stdout)
 		os.Exit(1)
-	default:
-		fmt.Printf("internal error: operation type %T not handled", op)
 	}
 }
 

cmd/kubectx/rename.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"strings"
 
@@ -9,6 +10,12 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+// RenameOp indicates intention to rename contexts.
+type RenameOp struct {
+	New string // NAME of New context
+	Old string // NAME of Old context (or '.' for current-context)
+}
+
 // parseRenameSyntax parses A=B form into [A,B] and returns
 // whether it is parsed correctly.
 func parseRenameSyntax(v string) (string, string, bool) {
@@ -26,7 +33,7 @@ func parseRenameSyntax(v string) (string, string, bool) {
 // rename changes the old (NAME or '.' for current-context)
 // to the "new" value. If the old refers to the current-context,
 // current-context preference is also updated.
-func renameContexts(old, new string) error {
+func (op RenameOp) Run(_, _ io.Writer) error {
 	f, rootNode, err := openKubeconfig()
 	if err != nil {
 		return nil
@@ -34,35 +41,29 @@ func renameContexts(old, new string) error {
 	defer f.Close()
 
 	cur := getCurrentContext(rootNode)
-	if old == "." {
+	if op.Old == "." {
-		old = cur
+		op.Old = cur
 	}
 
-	if !checkContextExists(rootNode, old) {
+	if !checkContextExists(rootNode, op.Old) {
-		return errors.Errorf("context %q not found, can't rename it", old)
+		return errors.Errorf("context %q not found, can't rename it", op.Old)
 	}
 
-	if checkContextExists(rootNode, new) {
+	if checkContextExists(rootNode, op.New) {
-		printWarning("context %q exists, overwriting it.", new)
+		printWarning("context %q exists, overwriting it.", op.New)
-		if err := modifyDocToDeleteContext(rootNode, new); err != nil {
+		if err := modifyDocToDeleteContext(rootNode, op.New); err != nil {
 			return errors.Wrap(err, "failed to delete new context to overwrite it")
 		}
 	}
 
-	if err := modifyContextName(rootNode, old, new); err != nil {
+	if err := modifyContextName(rootNode, op.Old, op.New); err != nil {
 		return errors.Wrap(err, "failed to change context name")
 	}
-
+	if op.New == cur {
-	if old == cur {
+		if err := modifyCurrentContext(rootNode, op.New); err != nil {
-		if err := modifyCurrentContext(rootNode, new); err != nil {
 			return errors.Wrap(err, "failed to set current-context to new name")
 		}
 	}
-
-	// TODO the next two functions are always repeated.
-	if err := resetFile(f); err != nil {
-		return err
-	}
 	if err := saveKubeconfigRaw(f, rootNode); err != nil {
 		return errors.Wrap(err, "failed to save modified kubeconfig")
 	}

cmd/kubectx/state.go

@@ -8,7 +8,7 @@ import (
 	"github.com/pkg/errors"
 )
 
-func kubectxFilePath() (string, error) {
+func kubectxPrevCtxFile() (string, error) {
 	home := homeDir()
 	if home == "" {
 		return "", errors.New("HOME or USERPROFILE environment variable not set")

cmd/kubectx/state_test.go

@@ -64,7 +64,7 @@ func Test_kubectxFilePath(t *testing.T) {
 	defer os.Setenv("HOME", origHome)
 
 	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "kubectx")
-	v, err := kubectxFilePath()
+	v, err := kubectxPrevCtxFile()
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -81,7 +81,7 @@ func Test_kubectxFilePath_error(t *testing.T) {
 	defer os.Setenv("HOME", origHome)
 	defer os.Setenv("USERPROFILE", origUserprofile)
 
-	_, err := kubectxFilePath()
+	_, err := kubectxPrevCtxFile()
 	if err == nil {
 		t.Fatal(err)
 	}

cmd/kubectx/switch.go

@@ -1,17 +1,40 @@
 package main
 
 import (
+	"fmt"
+	"io"
+
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v3"
 )
 
+// SwitchOp indicates intention to switch contexts.
+type SwitchOp struct {
+	Target string // '-' for back and forth, or NAME
+}
+
+func (op SwitchOp) Run(stdout, stderr io.Writer) error {
+	var newCtx string
+	var err error
+	if op.Target == "-" {
+		newCtx, err = swapContext()
+	} else {
+		newCtx, err = switchContext(op.Target)
+	}
+	if err != nil {
+		return errors.Wrap(err, "failed to switch context")
+	}
+	// TODO use printSuccess when available.
+	fmt.Fprintf(stderr, "Switched to context %q.\n", newCtx)
+	return nil
+}
+
 // switchContext switches to specified context name.
 func switchContext(name string) (string, error) {
-	stateFile, err := kubectxFilePath()
+	prevCtxFile, err := kubectxPrevCtxFile()
 	if err != nil {
 		return "", errors.Wrap(err, "failed to determine state file")
 	}
-
 	f, kc, err := openKubeconfig()
 	if err != nil {
 		return "", err
@@ -19,33 +42,42 @@ func switchContext(name string) (string, error) {
 	defer f.Close()
 
 	prev := getCurrentContext(kc)
-
+	if !checkContextExists(kc, name) {
-	// TODO: add a check to ensure user can't switch to non-existing context.
-	if !checkContextExists(kc, name)  {
 		return "", errors.Errorf("no context exists with the name: %q", name)
 	}
-
 	if err := modifyCurrentContext(kc, name); err != nil {
 		return "", err
 	}
-
-	if err := resetFile(f); err != nil {
-		return "", err
-	}
-
 	if err := saveKubeconfigRaw(f, kc); err != nil {
 		return "", errors.Wrap(err, "failed to save kubeconfig")
 	}
 
 	if prev != name {
-		if err := writeLastContext(stateFile, prev); err != nil {
+		if err := writeLastContext(prevCtxFile, prev); err != nil {
 			return "", errors.Wrap(err, "failed to save previous context name")
 		}
 	}
-
 	return name, nil
 }
 
+
+// swapContext switches to previously switch context.
+func swapContext() (string, error) {
+	prevCtxFile, err := kubectxPrevCtxFile()
+	if err != nil {
+		return "", errors.Wrap(err, "failed to determine state file")
+	}
+	prev, err := readLastContext(prevCtxFile)
+	if err != nil {
+		return "", errors.Wrap(err, "failed to read previous context file")
+	}
+	if prev == "" {
+		return "", errors.New("no previous context found")
+	}
+	return switchContext(prev)
+}
+
+
 func checkContextExists(rootNode *yaml.Node, name string) bool {
 	contexts := valueOf(rootNode, "contexts")
 	if contexts == nil {
@@ -83,22 +115,6 @@ func valueOf(mapNode *yaml.Node, key string) *yaml.Node {
 	return nil
 }
 
-// swapContext switches to previously switch context.
-func swapContext() (string, error) {
-	stateFile, err := kubectxFilePath()
-	if err != nil {
-		return "", errors.Wrap(err, "failed to determine state file")
-	}
-	prev, err := readLastContext(stateFile)
-	if err != nil {
-		return "", errors.Wrap(err, "failed to read previous context file")
-	}
-	if prev == "" {
-		return "", errors.New("no previous context found")
-	}
-	return switchContext(prev)
-}
-
 // getCurrentContext returns "current-context" value in given
 // kubeconfig object Node, or returns "" if not found.
 func getCurrentContext(rootNode *yaml.Node) string {

cmd/kubectx/unset.go

@@ -1,11 +1,17 @@
 package main
 
 import (
+	"fmt"
+	"io"
+
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v3"
 )
 
-func unsetContext() error {
+// UnsetOp indicates intention to remove current-context preference.
+type UnsetOp struct{}
+
+func (_ UnsetOp) Run(_, stderr io.Writer) error {
 	f, rootNode, err := openKubeconfig()
 	if err != nil {
 		return err
@@ -15,13 +21,12 @@ func unsetContext() error {
 	if err := modifyDocToUnsetContext(rootNode); err != nil {
 		return errors.Wrap(err, "error while modifying current-context")
 	}
-	if err := resetFile(f); err != nil {
-		return err
-	}
 	if err := saveKubeconfigRaw(f, rootNode); err != nil {
 		return errors.Wrap(err, "failed to save kubeconfig file after modification")
 	}
-	return nil
+
+	_, err = fmt.Fprintln(stderr, "Successfully unset the current context")
+	return err
 }
 
 func modifyDocToUnsetContext(rootNode *yaml.Node) error {