{7, 8, 32, 128, 256, skipNever},
	{8, 32, 128, 258, 1024, skipNever},
	{9, 32, 258, 258, 4096, skipNever},
}

type compressor struct {
	compressionLevel

	w          *huffmanBitWriter
	bulkHasher func([]byte, []uint32)

	// compression algorithm
	fill      func(*compressor, []byte) int // copy data to window
	step      func(*compressor)             // process window

		if err != nil {
			t.Fatalf("NewWriter: %v", err)
		}

		// DeepEqual doesn't compare functions.
		w.d.fill, wref.d.fill = nil, nil
		w.d.step, wref.d.step = nil, nil
		w.d.bulkHasher, wref.d.bulkHasher = nil, nil
		w.d.bestSpeed, wref.d.bestSpeed = nil, nil
		// hashMatch is always overwritten when used.
		copy(w.d.hashMatch[:], wref.d.hashMatch[:])
		if len(w.d.tokens) != 0 {