Fix plugin execution for Windows (knative#738)

Fixes knative#737

* Use exec.Command instend of syscall.Exec for windows.
* Fix a bug in plugin handler test when running it on windows.
* Fix typo.

CHANGELOG.adoc

@@ -26,6 +26,10 @@
 | Fix trigger create --filter flag to be optional
 | https://github.com/knative/client/pull/745[#745]
 
+| 🐛
+| Fix plugin execution for Windows.
+| https://github.com/knative/client/pull/738[#738]
+
 ## v0.13.0 (2020-03-11)
 
 [cols="1,10,3", options="header", width="100%"]

docs/plugins/README.md

@@ -5,7 +5,7 @@ Plugins follow a similar architecture to
 with some small differences. One key difference is that `kn` plugins can either
 live in your `PATH` or in a chosen and specified directory.
 [Kn plugins](https://github.com/knative/client/tree/master/docs/cmd/kn_plugin.md)
-shows how to install and create new plugins as well as gives some examples and
+show how to install and create new plugins as well as gives some examples and
 best practices.
 
 To see what plugins are installed on your machine, you can use the

pkg/kn/commands/plugin/handler.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"syscall"
 
@@ -93,6 +94,18 @@ func (h *DefaultPluginHandler) Lookup(name string) (string, bool) {
 
 // Execute implements PluginHandler
 func (h *DefaultPluginHandler) Execute(executablePath string, cmdArgs, environment []string) error {
+	if runtime.GOOS == "windows" {
+		cmd := exec.Command(executablePath, cmdArgs...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		cmd.Stdin = os.Stdin
+		cmd.Env = environment
+		err := cmd.Run()
+		if err == nil {
+			os.Exit(0)
+		}
+		return err
+	}
 	return syscall.Exec(executablePath, cmdArgs, environment)
 }
 

pkg/kn/commands/plugin/handler_test.go

@@ -19,6 +19,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 
 	"gotest.tools/assert"
@@ -45,6 +46,9 @@ func TestPluginHandler(t *testing.T) {
 
 	beforeEach := func(t *testing.T) {
 		pluginName = "fake"
+		if runtime.GOOS == "windows" {
+			pluginName += ".bat"
+		}
 		pluginPath = CreateTestPluginInPath(t, "kn-"+pluginName, KnTestPluginScript, FileModeExecutable, tmpPathDir)
 		assert.Assert(t, pluginPath != "")
 
@@ -134,6 +138,14 @@ func TestPluginHandler(t *testing.T) {
 			err = pluginHandler.Execute(bogusPath, []string{bogusPath}, os.Environ())
 			assert.Assert(t, err != nil, fmt.Sprintf("bogus plugin in path %s unexpectedly executed OK", bogusPath))
 		})
+		t.Run("executing fake plugin successfully", func(t *testing.T) {
+			setup(t)
+			defer cleanup(t)
+			beforeEach(t)
+
+			err = pluginHandler.Execute(pluginPath, []string{}, os.Environ())
+			assert.Assert(t, err == nil, fmt.Sprintf("fail to execute fake plugin in path %s ", pluginPath))
+		})
 	})
 
 	t.Run("HandlePluginCommand", func(t *testing.T) {

pkg/kn/commands/plugin/plugin_test_helper.go

@@ -18,7 +18,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"runtime"
 	"testing"
 
 	"github.com/spf13/cobra"
@@ -58,13 +57,9 @@ func CreateTestPlugin(t *testing.T, name, script string, fileMode os.FileMode) s
 // CreateTestPluginInPath with name, path, script, and fileMode and return the tmp random path
 func CreateTestPluginInPath(t *testing.T, name, script string, fileMode os.FileMode, path string) string {
 	fullPath := filepath.Join(path, name)
-	if runtime.GOOS == "windows" {
-		fullPath += ".bat"
-	}
 	err := ioutil.WriteFile(fullPath, []byte(script), fileMode)
 	assert.NilError(t, err)
-
-	return filepath.Join(path, name)
+	return fullPath
 }
 
 // DeleteTestPlugin with path