t.Fatal(err)
	}
	if _, err = reader.ReadAt(b, 20); err != nil {
		t.Fatal(err)
	}
	if _, err = reader.ReadAt(b[:5], 30); err != nil {
		t.Fatal(err)
	}
	if br, ok := reader.(io.Closer); ok {
		br.Close()
	}
}

func TestAllBitrotAlgorithms(t *testing.T) {
	for bitrotAlgo := range bitrotAlgorithms {
		testBitrotReaderWriterAlgo(t, bitrotAlgo)
	}

}

// Close all the readers.
func closeBitrotReaders(rs []io.ReaderAt) {
	for _, r := range rs {
		if r != nil {
			if br, ok := r.(io.Closer); ok {
				br.Close()
			}
		}
	}
}

// Close all the writers.
func closeBitrotWriters(ws []io.Writer) {
	for _, w := range ws {
		if w != nil {
			if bw, ok := w.(io.Closer); ok {