}
			break
		}
		got += string(r1)
		// Put it back and read it again.
		if err = r.UnreadRune(); err != nil {
			t.Fatal("unexpected error on UnreadRune:", err)
		}
		r2, _, err := r.ReadRune()
		if err != nil {
			t.Fatal("unexpected error reading after unreading:", err)
		}
		if r1 != r2 {
			t.Fatalf("incorrect rune after unread: got %c, want %c", r1, r2)
		}
	}