It's pretty simple. I'm decoding a structure into bit fields (802.11 Information Element). I have a hex dump that I decode into a two structures with almost 100 fields (eyeroll for 802.11 committee). Each field can only be 0, 1, or sometimes up to 15.
I have a list of the structure members. I generate an assert for each member being a certain value. The python script builds/runs the C code. On failure, I parse the assertion failure, get the actual value, change the C assert string, rebuild-rerun. Continue until the program succeeds.
I've visually verified the decode is correct once. I want to keep the decoder tested if I change the code again so I'm generating complete test coverage.
It sounds like your use case is property based testing. Have you tried any of the QuickCheck ports to C++? My favorite is RapidCheck (https://github.com/emil-e/rapidcheck). You define generators for your struct fields and write a pure function to check whether the parsed output conforms to your expectations.
I have a list of the structure members. I generate an assert for each member being a certain value. The python script builds/runs the C code. On failure, I parse the assertion failure, get the actual value, change the C assert string, rebuild-rerun. Continue until the program succeeds.
I've visually verified the decode is correct once. I want to keep the decoder tested if I change the code again so I'm generating complete test coverage.