br := NewReader(strings.NewReader("example"))
	br.ReadByte()
	br.Peek(1)
	if err := br.UnreadByte(); err == nil {
		t.Error("UnreadByte didn't fail after Peek")
	}
}

func TestNoUnreadRuneAfterDiscard(t *testing.T) {
	br := NewReader(strings.NewReader("example"))
	br.ReadRune()
	br.Discard(1)
	if err := br.UnreadRune(); err == nil {
		t.Error("UnreadRune didn't fail after Discard")
	}
}