do not check for plugin executable if none on path

pkg/kn/commands/plugin/handler.go

@@ -15,7 +15,6 @@
 package plugin
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -127,10 +126,11 @@ func HandlePluginCommand(pluginHandler PluginHandler, cmdArgs []string) error {
 	remainingArgs := []string{}
 
 	for idx := range cmdArgs {
-		if strings.HasPrefix(cmdArgs[idx], "-") {
+		cmdArg := cmdArgs[idx]
+		if strings.HasPrefix(cmdArg, "-") {
 			continue
 		}
-		remainingArgs = append(remainingArgs, strings.Replace(cmdArgs[idx], "-", "_", -1))
+		remainingArgs = append(remainingArgs, strings.Replace(cmdArg, "-", "_", -1))
 	}
 
 	foundBinaryPath := ""
@@ -147,16 +147,14 @@ func HandlePluginCommand(pluginHandler PluginHandler, cmdArgs []string) error {
 		break
 	}
 
-	if len(foundBinaryPath) == 0 {
-		return errors.New("Could not find plugin to execute")
-	}
-
 	// invoke cmd binary relaying the current environment and args given
 	// remainingArgs will always have at least one element.
 	// execve will make remainingArgs[0] the "binary name".
-	err := pluginHandler.Execute(foundBinaryPath, append([]string{foundBinaryPath}, cmdArgs[len(remainingArgs):]...), os.Environ())
-	if err != nil {
-		return err
+	if len(foundBinaryPath) != 0 {
+		err := pluginHandler.Execute(foundBinaryPath, append([]string{foundBinaryPath}, cmdArgs[len(remainingArgs):]...), os.Environ())
+		if err != nil {
+			return err
+		}
 	}
 
 	return nil

pkg/kn/commands/plugin/handler_test.go

@@ -165,6 +165,14 @@ func TestPluginHandler(t *testing.T) {
 			err = HandlePluginCommand(tPluginHandler, []string{"bogus"})
 			assert.Assert(t, err != nil, fmt.Sprintf("test plugin %s expected to fail executing", "bogus"))
 		})
+
+		t.Run("doesn't return error with -h", func(t *testing.T) {
+			setup(t)
+			defer cleanup(t)
+
+			err = HandlePluginCommand(tPluginHandler, []string{"source", "-h"})
+			assert.Assert(t, err == nil, fmt.Sprintf("test plugin command with -h failed executing: %s", err.Error()))
+		})
 	})
 }
 

pkg/kn/core/root.go

@@ -87,7 +87,8 @@ func NewDefaultKnCommandWithArgs(rootCmd *cobra.Command,
 				fmt.Fprintf(rootCmd.OutOrStderr(), "Error: unknown command '%s' \nRun 'kn --help' for usage.\n", args[1])
 				os.Exit(1)
 			}
-		} else if foundCmd.HasSubCommands() {
+		}
+		if foundCmd.HasSubCommands() {
 			if _, _, err := rootCmd.Find(innerArgs); err != nil {
 				fmt.Fprintf(rootCmd.OutOrStderr(), showSubcommands(foundCmd, cmdPathPieces, innerArgs[0]))
 				os.Exit(1)