Shorter stack traces in tests

[aanand]

We don't need the full-blown "here's the code of the massive library method that your error came from" report that py.test gives you by default.

[dnephin]

If you want to just make this default, you could do this https://pytest.org/latest/customize.html#adding-default-options

[aanand]

@dnephin nice, I'll update it

[shin-]

Actually, if something fails, the more verbose the better I think... It's not always useful but I'll take too much information over not enough of it. :x

[dnephin]

I personally always use --tb=short, you still get the full traceback (filename and line number) for the relevant stack frames, it just doesn't show you the full source for every function.

https://pytest.org/latest/usage.html#modifying-python-traceback-printing

LGTM

[mnowster]

LGTM