t.Errorf("Test %d: should fail but it passed", i)
		}
		if err == nil {
			if content := writer.Bytes(); !bytes.Equal(content, data[test.offset:test.offset+test.length]) {
				t.Errorf("Test %d: read returns wrong file content.", i)
			}
		}

		for i, r := range bitrotReaders {
			if r == nil {
				disks[i] = OfflineDisk
			}
		}
		if err == nil && !test.shouldFail {