}
	check(t, &b, "hello ")
	n, err = b.WriteString("world")
	if err != nil || n != 5 {
		t.Errorf("WriteString: got %d,%s; want 5,nil", n, err)
	}
	check(t, &b, "hello world")
}

func TestBuilderString(t *testing.T) {
	var b Builder
	b.WriteString("alpha")
	check(t, &b, "alpha")
	s1 := b.String()
	b.WriteString("beta")
	check(t, &b, "alphabeta")
	s2 := b.String()
	b.WriteString("gamma")