got := new(bytes.Buffer)
	var want []byte
	rn := rand.New(rand.NewSource(0))
	w := NewWriterSize(got, 64)
	for i := 0; i < 100; i++ {
		// Obtain a buffer to append to.
		b := w.AvailableBuffer()
		if w.Available() != cap(b) {
			t.Fatalf("Available() = %v, want %v", w.Available(), cap(b))
		}

		// While not recommended, it is valid to append to a shifted buffer.