}
	if len(v) != 3 {
		t.Fatal("expected 3 args; got ", len(v))
	}
	expect := "[1 2 3]"
	if v.String() != expect {
		t.Errorf("expected value %q got %q", expect, v.String())
	}
}

func TestUserDefinedFunc(t *testing.T) {
	flags := NewFlagSet("test", ContinueOnError)
	flags.SetOutput(io.Discard)
	var ss []string
	flags.Func("v", "usage", func(s string) error {
		ss = append(ss, s)
		return nil
	})