Merge pull request #8919 from gyuho/exec-watch

etcdctl: support exec watch in v3

e2e/ctl_v3_auth_test.go

@@ -780,32 +780,32 @@ func authTestWatch(cx ctlCtx) {
 		puts []kv
 		args []string
 
-		wkv  []kv
+		wkv  []kvExec
 		want bool
 	}{
 		{ // watch 1 key, should be successful
 			[]kv{{"key", "value"}},
 			[]string{"key", "--rev", "1"},
-			[]kv{{"key", "value"}},
+			[]kvExec{{key: "key", val: "value"}},
 			true,
 		},
 		{ // watch 3 keys by range, should be successful
 			[]kv{{"key1", "val1"}, {"key3", "val3"}, {"key2", "val2"}},
 			[]string{"key", "key3", "--rev", "1"},
-			[]kv{{"key1", "val1"}, {"key2", "val2"}},
+			[]kvExec{{key: "key1", val: "val1"}, {key: "key2", val: "val2"}},
 			true,
 		},
 
 		{ // watch 1 key, should not be successful
 			[]kv{},
 			[]string{"key5", "--rev", "1"},
-			[]kv{},
+			[]kvExec{},
 			false,
 		},
 		{ // watch 3 keys by range, should not be successful
 			[]kv{},
 			[]string{"key", "key6", "--rev", "1"},
-			[]kv{},
+			[]kvExec{},
 			false,
 		},
 	}

e2e/ctl_v3_make_mirror_test.go

@@ -28,16 +28,17 @@ func makeMirrorTest(cx ctlCtx) {
 	var (
 		flags  = []string{}
 		kvs    = []kv{{"key1", "val1"}, {"key2", "val2"}, {"key3", "val3"}}
+		kvs2   = []kvExec{{key: "key1", val: "val1"}, {key: "key2", val: "val2"}, {key: "key3", val: "val3"}}
 		prefix = "key"
 	)
-	testMirrorCommand(cx, flags, kvs, kvs, prefix, prefix)
+	testMirrorCommand(cx, flags, kvs, kvs2, prefix, prefix)
 }
 
 func makeMirrorModifyDestPrefixTest(cx ctlCtx) {
 	var (
 		flags      = []string{"--prefix", "o_", "--dest-prefix", "d_"}
 		kvs        = []kv{{"o_key1", "val1"}, {"o_key2", "val2"}, {"o_key3", "val3"}}
-		kvs2       = []kv{{"d_key1", "val1"}, {"d_key2", "val2"}, {"d_key3", "val3"}}
+		kvs2       = []kvExec{{key: "d_key1", val: "val1"}, {key: "d_key2", val: "val2"}, {key: "d_key3", val: "val3"}}
 		srcprefix  = "o_"
 		destprefix = "d_"
 	)
@@ -48,7 +49,7 @@ func makeMirrorNoDestPrefixTest(cx ctlCtx) {
 	var (
 		flags      = []string{"--prefix", "o_", "--no-dest-prefix"}
 		kvs        = []kv{{"o_key1", "val1"}, {"o_key2", "val2"}, {"o_key3", "val3"}}
-		kvs2       = []kv{{"key1", "val1"}, {"key2", "val2"}, {"key3", "val3"}}
+		kvs2       = []kvExec{{key: "key1", val: "val1"}, {key: "key2", val: "val2"}, {key: "key3", val: "val3"}}
 		srcprefix  = "o_"
 		destprefix = "key"
 	)
@@ -56,7 +57,7 @@ func makeMirrorNoDestPrefixTest(cx ctlCtx) {
 	testMirrorCommand(cx, flags, kvs, kvs2, srcprefix, destprefix)
 }
 
-func testMirrorCommand(cx ctlCtx, flags []string, sourcekvs, destkvs []kv, srcprefix, destprefix string) {
+func testMirrorCommand(cx ctlCtx, flags []string, sourcekvs []kv, destkvs []kvExec, srcprefix, destprefix string) {
 	// set up another cluster to mirror with
 	mirrorcfg := configAutoTLS
 	mirrorcfg.clusterSize = 1

e2e/ctl_v3_watch_test.go

@@ -38,32 +38,62 @@ func TestCtlV3WatchInteractivePeerTLS(t *testing.T) {
 	testCtl(t, watchTest, withInteractive(), withCfg(configPeerTLS))
 }
 
+type kvExec struct {
+	key, val   string
+	execOutput string
+}
+
 func watchTest(cx ctlCtx) {
 	tests := []struct {
 		puts []kv
 		args []string
 
-		wkv []kv
+		wkv []kvExec
 	}{
 		{ // watch 1 key
 			[]kv{{"sample", "value"}},
 			[]string{"sample", "--rev", "1"},
+			[]kvExec{{key: "sample", val: "value"}},
+		},
+		{ // watch 1 key with "echo watch event received"
 			[]kv{{"sample", "value"}},
+			[]string{"sample", "--rev", "1", "--", "echo", "watch event received"},
+			[]kvExec{{key: "sample", val: "value", execOutput: "watch event received"}},
+		},
+		{ // watch 1 key with "echo watch event received"
+			[]kv{{"sample", "value"}},
+			[]string{"--rev", "1", "sample", "--", "echo", "watch event received"},
+			[]kvExec{{key: "sample", val: "value", execOutput: "watch event received"}},
+		},
+		{ // watch 1 key with "echo \"Hello World!\""
+			[]kv{{"sample", "value"}},
+			[]string{"--rev", "1", "sample", "--", "echo", "\"Hello World!\""},
+			[]kvExec{{key: "sample", val: "value", execOutput: "Hello World!"}},
+		},
+		{ // watch 1 key with "echo watch event received"
+			[]kv{{"sample", "value"}},
+			[]string{"sample", "samplx", "--rev", "1", "--", "echo", "watch event received"},
+			[]kvExec{{key: "sample", val: "value", execOutput: "watch event received"}},
+		},
+		{ // watch 1 key with "echo watch event received"
+			[]kv{{"sample", "value"}},
+			[]string{"sample", "--rev", "1", "samplx", "--", "echo", "watch event received"},
+			[]kvExec{{key: "sample", val: "value", execOutput: "watch event received"}},
 		},
 		{ // watch 3 keys by prefix
 			[]kv{{"key1", "val1"}, {"key2", "val2"}, {"key3", "val3"}},
 			[]string{"key", "--rev", "1", "--prefix"},
-			[]kv{{"key1", "val1"}, {"key2", "val2"}, {"key3", "val3"}},
+			[]kvExec{{key: "key1", val: "val1"}, {key: "key2", val: "val2"}, {key: "key3", val: "val3"}},
 		},
 		{ // watch by revision
 			[]kv{{"etcd", "revision_1"}, {"etcd", "revision_2"}, {"etcd", "revision_3"}},
 			[]string{"etcd", "--rev", "2"},
-			[]kv{{"etcd", "revision_2"}, {"etcd", "revision_3"}},
+			[]kvExec{{key: "etcd", val: "revision_2"}, {key: "etcd", val: "revision_3"}},
 		},
 		{ // watch 3 keys by range
 			[]kv{{"key1", "val1"}, {"key3", "val3"}, {"key2", "val2"}},
 			[]string{"key", "key3", "--rev", "1"},
-			[]kv{{"key1", "val1"}, {"key2", "val2"}},
+			[]kvExec{{key: "key1", val: "val1"}, {key: "key2", val: "val2"}},
 		},
 	}
 
@@ -97,7 +127,7 @@ func setupWatchArgs(cx ctlCtx, args []string) []string {
 	return cmdArgs
 }
 
-func ctlV3Watch(cx ctlCtx, args []string, kvs ...kv) error {
+func ctlV3Watch(cx ctlCtx, args []string, kvs ...kvExec) error {
 	cmdArgs := setupWatchArgs(cx, args)
 
 	proc, err := spawnCmd(cmdArgs)
@@ -119,6 +149,11 @@ func ctlV3Watch(cx ctlCtx, args []string, kvs ...kv) error {
 		if _, err = proc.Expect(elem.val); err != nil {
 			return err
 		}
+		if elem.execOutput != "" {
+			if _, err = proc.Expect(elem.execOutput); err != nil {
+				return err
+			}
+		}
 	}
 	return proc.Stop()
 }

etcdctl/README.md

@@ -337,7 +337,7 @@ Prints the compacted revision.
 # compacted revision 1234
 ```
 
-### WATCH [options] [key or prefix] [range_end]
+### WATCH [options] [key or prefix] [range_end] [--] [exec-command arg1 arg2 ...]
 
 Watch watches events stream on keys or prefixes, [key or prefix, range_end) if `range-end` is given. The watch command runs until it encounters an error or is terminated by the user.  If range_end is given, it must be lexicographically greater than key or "\x00".
 
@@ -378,6 +378,16 @@ watch [options] <key or prefix>\n
 # bar
 ```
 
+Receive events and execute `echo watch event received`:
+
+```bash
+./etcdctl watch foo -- echo watch event received
+# PUT
+# foo
+# bar
+# watch event received
+```
+
 ##### Interactive
 
 ```bash
@@ -392,6 +402,17 @@ watch foo
 # bar
 ```
 
+Receive events and execute `echo watch event received`:
+
+```bash
+./etcdctl watch -i
+watch foo -- echo watch event received
+# PUT
+# foo
+# bar
+# watch event received
+```
+
 ### LEASE \<subcommand\>
 
 LEASE provides commands for key lease management.

etcdctl/ctlv3/command/watch_command.go

@@ -17,8 +17,10 @@ package command
 import (
 	"bufio"
 	"context"
+	"errors"
 	"fmt"
 	"os"
+	"os/exec"
 	"strings"
 
 	"github.com/coreos/etcd/clientv3"
@@ -26,6 +28,12 @@ import (
 	"github.com/spf13/cobra"
 )
 
+var (
+	errBadArgsNum              = errors.New("bad number of arguments")
+	errBadArgsNumSeparator     = errors.New("bad number of arguments (found separator --, but no commands)")
+	errBadArgsInteractiveWatch = errors.New("args[0] must be 'watch' for interactive calls")
+)
+
 var (
 	watchRev         int64
 	watchPrefix      bool
@@ -36,7 +44,7 @@ var (
 // NewWatchCommand returns the cobra command for "watch".
 func NewWatchCommand() *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "watch [options] [key or prefix] [range_end]",
+		Use:   "watch [options] [key or prefix] [range_end] [--] [exec-command arg1 arg2 ...]",
 		Short: "Watches events stream on keys or prefixes",
 		Run:   watchCommandFunc,
 	}
@@ -52,24 +60,29 @@ func NewWatchCommand() *cobra.Command {
 // watchCommandFunc executes the "watch" command.
 func watchCommandFunc(cmd *cobra.Command, args []string) {
 	if watchInteractive {
-		watchInteractiveFunc(cmd, args)
+		watchInteractiveFunc(cmd, os.Args)
 		return
 	}
 
-	c := mustClientFromCmd(cmd)
+	watchArgs, execArgs, err := parseWatchArgs(os.Args, args, false)
-	wc, err := getWatchChan(c, args)
 	if err != nil {
 		ExitWithError(ExitBadArgs, err)
 	}
 
-	printWatchCh(wc)
+	c := mustClientFromCmd(cmd)
+	wc, err := getWatchChan(c, watchArgs)
+	if err != nil {
+		ExitWithError(ExitBadArgs, err)
+	}
+
+	printWatchCh(c, wc, execArgs)
 	if err = c.Close(); err != nil {
 		ExitWithError(ExitBadConnection, err)
 	}
 	ExitWithError(ExitInterrupted, fmt.Errorf("watch is canceled by the server"))
 }
 
-func watchInteractiveFunc(cmd *cobra.Command, args []string) {
+func watchInteractiveFunc(cmd *cobra.Command, osArgs []string) {
 	c := mustClientFromCmd(cmd)
 
 	reader := bufio.NewReader(os.Stdin)
@@ -92,25 +105,25 @@ func watchInteractiveFunc(cmd *cobra.Command, args []string) {
 			continue
 		}
 
-		flagset := NewWatchCommand().Flags()
+		watchArgs, execArgs, perr := parseWatchArgs(osArgs, args, true)
-		err = flagset.Parse(args[1:])
+		if perr != nil {
+			ExitWithError(ExitBadArgs, perr)
+		}
+
+		ch, err := getWatchChan(c, watchArgs)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Invalid command %s (%v)\n", l, err)
 			continue
 		}
-		ch, err := getWatchChan(c, flagset.Args())
+		go printWatchCh(c, ch, execArgs)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "Invalid command %s (%v)\n", l, err)
-			continue
-		}
-		go printWatchCh(ch)
 	}
 }
 
 func getWatchChan(c *clientv3.Client, args []string) (clientv3.WatchChan, error) {
-	if len(args) < 1 || len(args) > 2 {
+	if len(args) < 1 {
-		return nil, fmt.Errorf("bad number of arguments")
+		return nil, errBadArgsNum
 	}
+
 	key := args[0]
 	opts := []clientv3.OpOption{clientv3.WithRev(watchRev)}
 	if len(args) == 2 {
@@ -128,11 +141,99 @@ func getWatchChan(c *clientv3.Client, args []string) (clientv3.WatchChan, error)
 	return c.Watch(clientv3.WithRequireLeader(context.Background()), key, opts...), nil
 }
 
-func printWatchCh(ch clientv3.WatchChan) {
+func printWatchCh(c *clientv3.Client, ch clientv3.WatchChan, execArgs []string) {
 	for resp := range ch {
 		if resp.Canceled {
 			fmt.Fprintf(os.Stderr, "watch was canceled (%v)\n", resp.Err())
 		}
 		display.Watch(resp)
+
+		if len(execArgs) > 0 {
+			cmd := exec.CommandContext(c.Ctx(), execArgs[0], execArgs[1:]...)
+			cmd.Env = os.Environ()
+			cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr
+			if err := cmd.Run(); err != nil {
+				fmt.Fprintf(os.Stderr, "command %q error (%v)\n", execArgs, err)
+			}
+		}
 	}
 }
+
+// "commandArgs" is the command arguments after "spf13/cobra" parses
+// all "watch" command flags, strips out special characters (e.g. "--").
+// "orArgs" is the raw arguments passed to "watch" command
+// (e.g. ./bin/etcdctl watch foo --rev 1 bar).
+// "--" characters are invalid arguments for "spf13/cobra" library,
+// so no need to handle such cases.
+func parseWatchArgs(osArgs, commandArgs []string, interactive bool) (watchArgs []string, execArgs []string, err error) {
+	watchArgs = commandArgs
+
+	// remove preceding commands (e.g. "watch foo bar" in interactive mode)
+	idx := 0
+	for idx = range watchArgs {
+		if watchArgs[idx] == "watch" {
+			break
+		}
+	}
+	if idx < len(watchArgs)-1 {
+		watchArgs = watchArgs[idx+1:]
+	} else if interactive { // "watch" not found
+		return nil, nil, errBadArgsInteractiveWatch
+	}
+	if len(watchArgs) < 1 {
+		return nil, nil, errBadArgsNum
+	}
+
+	// remove preceding commands (e.g. ./bin/etcdctl watch)
+	for idx = range osArgs {
+		if osArgs[idx] == "watch" {
+			break
+		}
+	}
+	if idx < len(osArgs)-1 {
+		osArgs = osArgs[idx+1:]
+	} else {
+		return nil, nil, errBadArgsNum
+	}
+
+	argsWithSep := osArgs
+	if interactive { // interactive mode pass "--" to the command args
+		argsWithSep = watchArgs
+	}
+	foundSep := false
+	for idx = range argsWithSep {
+		if argsWithSep[idx] == "--" && idx > 0 {
+			foundSep = true
+			break
+		}
+	}
+	if interactive {
+		flagset := NewWatchCommand().Flags()
+		if err := flagset.Parse(argsWithSep); err != nil {
+			return nil, nil, err
+		}
+		watchArgs = flagset.Args()
+	}
+	if !foundSep {
+		return watchArgs, nil, nil
+	}
+
+	if idx == len(argsWithSep)-1 {
+		// "watch foo bar --" should error
+		return nil, nil, errBadArgsNumSeparator
+	}
+	execArgs = argsWithSep[idx+1:]
+
+	// "watch foo bar --rev 1 -- echo hello" or "watch foo --rev 1 bar -- echo hello",
+	// then "watchArgs" is "foo bar echo hello"
+	// so need ignore args after "argsWithSep[idx]", which is "--"
+	endIdx := 0
+	for endIdx = len(watchArgs) - 1; endIdx >= 0; endIdx-- {
+		if watchArgs[endIdx] == argsWithSep[idx+1] {
+			break
+		}
+	}
+	watchArgs = watchArgs[:endIdx]
+
+	return watchArgs, execArgs, nil
+}

etcdctl/ctlv3/command/watch_command_test.go

@@ -0,0 +1,213 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package command
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_parseWatchArgs(t *testing.T) {
+	tt := []struct {
+		osArgs      []string // raw arguments to "watch" command
+		commandArgs []string // arguments after "spf13/cobra" preprocessing
+		interactive bool
+
+		watchArgs []string
+		execArgs  []string
+		err       error
+	}{
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "bar"},
+			commandArgs: []string{"foo", "bar"},
+			interactive: false,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "bar", "--"},
+			commandArgs: []string{"foo", "bar"},
+			interactive: false,
+			watchArgs:   nil,
+			execArgs:    nil,
+			err:         errBadArgsNumSeparator,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo"},
+			commandArgs: []string{"foo"},
+			interactive: false,
+			watchArgs:   []string{"foo"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "--rev", "1", "foo"},
+			commandArgs: []string{"foo"},
+			interactive: false,
+			watchArgs:   []string{"foo"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "--rev", "1"},
+			commandArgs: []string{"foo"},
+			interactive: false,
+			watchArgs:   []string{"foo"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "--rev", "1", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "bar", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "bar", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "--rev", "1", "foo", "bar", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "bar", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "--rev", "1", "bar", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "bar", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "foo", "bar", "--rev", "1", "--", "echo", "Hello", "World"},
+			commandArgs: []string{"foo", "bar", "echo", "Hello", "World"},
+			interactive: false,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"foo", "bar", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   nil,
+			execArgs:    nil,
+			err:         errBadArgsInteractiveWatch,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo"},
+			interactive: true,
+			watchArgs:   []string{"foo"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "bar"},
+			interactive: true,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "--rev", "1"},
+			interactive: true,
+			watchArgs:   []string{"foo"},
+			execArgs:    nil,
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "--rev", "1", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "--rev", "1", "foo", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "bar", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "--rev", "1", "foo", "bar", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "--rev", "1", "bar", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+		{
+			osArgs:      []string{"./bin/etcdctl", "watch", "-i"},
+			commandArgs: []string{"watch", "foo", "bar", "--rev", "1", "--", "echo", "Hello", "World"},
+			interactive: true,
+			watchArgs:   []string{"foo", "bar"},
+			execArgs:    []string{"echo", "Hello", "World"},
+			err:         nil,
+		},
+	}
+	for i, ts := range tt {
+		watchArgs, execArgs, err := parseWatchArgs(ts.osArgs, ts.commandArgs, ts.interactive)
+		if err != ts.err {
+			t.Fatalf("#%d: error expected %v, got %v", i, ts.err, err)
+		}
+		if !reflect.DeepEqual(watchArgs, ts.watchArgs) {
+			t.Fatalf("#%d: watchArgs expected %q, got %v", i, ts.watchArgs, watchArgs)
+		}
+		if !reflect.DeepEqual(execArgs, ts.execArgs) {
+			t.Fatalf("#%d: execArgs expected %q, got %v", i, ts.execArgs, execArgs)
+		}
+	}
+}