Testing refactor

[chrisconlan]

We've explored unittest, pytest, pandas._testing, as well as a basic framework using Python's __main__ construct and assert statements.

Avoid frameworks like uniuttest and pytest for now. Use this pattern instead ...

def f():
    ...
    return something

if __name__ == '__main__':
    assert f() == something, 'it is broken'

[chrisconlan]

Let's refactor our code to use this testing framework throughout.

[emican]

Unittest removed
Validation tests expanded
profiler_v2.time_this is called as a function on imported functions

Validation tests in separate .csv files add complexity. It was nice to be able to see the ground truth example in the main section.