// 4 MB block.
	// Approx runtime ~30ms
	data := make([]byte, 4<<20)
	rng := rand.New(rand.NewSource(0))
	for i := range data {
		// Generate compressible stream...
		data[i] = byte(rng.Int63() & 3)
	}
	failOnErr := func(err error) {
		if err != nil {
			logger.Fatal(errSelfTestFailure, "compress: error on self-test: %v", err)
		}
	}
	const skip = 2<<20 + 511