t.Errorf("w.Flush() = %v, want nil", err)
	}

	if got, want := rfw.writeBytes, bufsize; got != want {
		t.Errorf("wrote %v bytes with Write, want %v", got, want)
	}
	if got, want := rfw.readFromBytes, len(input)-bufsize; got != want {
		t.Errorf("wrote %v bytes with ReadFrom, want %v", got, want)
	}
}

func TestReadZero(t *testing.T) {
	for _, size := range []int{100, 2} {