Unit tests depend on functions not being tested

[cwhanse]

test_irradiance.py uses

ephem_data = solarposition.get_solarposition(
    times, tus.latitude, tus.longitude, method='nrel_numpy')

irrad_data = tus.get_clearsky(times, model='ineichen', linke_turbidity=3)

dni_et = irradiance.extraradiation(times.dayofyear)

to compute known values for unit tests. This dependence on functions not under test could cause a unit test to fail when the unit's code is unchanged.

[wholmgren]

@cwhanse I reviewed the tests and I believe we can close this issue now that the PRs referenced above have been merged.

test_atmosphere.py uses a similar pattern as shown in your description, but the returned values are not explicitly tested. There is already another issue, #158, for improving that test module.

[cwhanse]

I agree, let's close this issue. If we find more tests with dependencies, we can reference this conversation, and fix those tests with their own issue and PR.