Replace unittest with pytest

[Alopalao]

Closes #88

Summary

Replace unittest with pytest

Local Tests

Run tox

End-to-End Tests

N/A

[Alopalao]

Overall number of test have been reduced drastically from 400 to 247 but the percentage of coverage is the same. This is because every child of tests/unit/test_utils.py now does not call a second time every test from its parent. Is this correct?

[viniarck]

Overall number of test have been reduced drastically from 400 to 247 but the percentage of coverage is the same. This is because every child of tests/unit/test_utils.py now does not call a second time every test from its parent. Is this correct?

Prev  (stmt / miss / percent) : 5990    373    94%
After (stmt / miss / percent) : 5795    375    94%

@Alopalao indeed the number of displayed collected test cases changed, but yes, coverage is equivalent, maybe with unitest.TestCase it was counting more than once in certain cases due to inheritance base class also being a test.

I've also looked into a detailed diff comparing the execution and I noticed no relevant difference. By the way, pretty neat how StructTest ended up, relatively minimal refactoring in that part while still compatible.

[viniarck]

Excellent PR, Aldo.

LGTM. This will be shipped soon.