t.Fatalf("expect 16 abcd and 4 1234 but got %s. r.w=%d, r.r=%d", rb.Bytes(nil), rb.w, rb.r)
	}
}

func TestRingBuffer_WriteBlocking(t *testing.T) {
	rb := New(64).SetBlocking(true)

	// check empty or full
	if !rb.IsEmpty() {
		t.Fatalf("expect IsEmpty is true but got false")
	}
	if rb.IsFull() {