Best way to test CRC logic?

Question

How can I verify two CRC implementations will generate the same checksums?

I'm looking for an exhaustive implementation evaluating methodology specific to CRC.

Answer 1

You can separate the problem into edge cases and random samples.

Edge cases. There are two variables to the CRC input, number of bytes, and value of each byte. So create arrays of 0, 1, and MAX_BYTES, with values ranging from 0 to MAX_BYTE_VALUE. The edge case suite will be something you'll most likely want to keep within a JUnit suite.

Random samples. Using the ranges above, run CRC on randomly generated arrays of bytes in a loop. The longer you let the loop run, the more you exhaust the inputs. If you are low on computing power, consider deploying the test to EC2.

Answer 2

Create several unit tests with the same input that will compare the output of both implementations against each other.