This! Especially with pandas.
I did have a look at numpy and on my machine the tests did not bloat it as much as you made me believe. The `core/tests/` modules are 3MB and the `__pycache__` doubled it to 6MB. What do you refer to as "test case artifacts"? The modules, pycache, or both?
Also, wrt you statement on pandas; is it the debug symbols that account for the bloat, or the libs themselves?