add typo suggestion test (levenshtein distance)

command.go

@@ -325,7 +325,7 @@ func (c *Command) getSuggestions(unknownCmd string) []string {
 func (c *Command) formatUnknownCommandError(unknownCmd string) error {
 	suggestions := c.getSuggestions(unknownCmd)
 	if len(suggestions) > 0 {
-		return fmt.Errorf("unknown command %q\nDid you mean one of these?\n\t%s",
+		return fmt.Errorf("unknown command %q. Did you mean one of these?\n\t%s",
 			unknownCmd,
 			strings.Join(suggestions, "\n\t"))
 	}

run_test.go

@@ -13,6 +13,7 @@ func TestRun(t *testing.T) {
 	t.Parallel()
 
 	t.Run("parse and run", func(t *testing.T) {
+		t.Parallel()
 		var count int
 
 		root := &Command{
@@ -59,4 +60,27 @@ func TestRun(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, 3, count)
 	})
+	t.Run("typo suggestion", func(t *testing.T) {
+		t.Parallel()
+		root := &Command{
+			Name:  "count",
+			Usage: "count [flags] [command]",
+			SubCommands: []*Command{
+				{
+					Name:  "version",
+					Usage: "show version",
+					Exec: func(ctx context.Context, s *State) error {
+						_, _ = s.Stdout.Write([]byte("1.0.0\n"))
+						return nil
+					},
+				},
+			},
+			Exec: func(ctx context.Context, s *State) error { return nil },
+		}
+
+		err := ParseAndRun(context.Background(), root, []string{"verzion"}, nil)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), `unknown command "verzion". Did you mean one of these?`)
+		require.Contains(t, err.Error(), `	version`)
+	})
 }