Default values for positional arugments follow a rule, so if an argument has a
default value, later positional arguments must also have default values.
The database only stores the actual default values, and nothing about the
arguments that doesn't have default values.
This turns out to be a major problem for Argument.getKwDefault(i), since default
values for keyword-only arguments doesn't have the same rule. So if you know
there is one default value, you can't tell if it is associated with `foo` or
`bar`, as in the examples below:
```
def a(*, foo=None, bar):
pass
def b(*, foo, bar=None):
pass
```
How could the tests fail because of autoformatting, you may ask?
The answer is deprecation warnings. These specify the location of the deprecated
entity, and due to autoformatting these moved around.
For syntax errors, we simply report the major version.
For unused imports, we were getting a result for `typing.py` when run under
Python 3.7.3. To prevent this import from being considered, I've set the maximum
import depth to `0`.
This is a temporary fix!
Added minimal working example (MWE) as a regression, so it's easier to fix the
real problem.
only Python 3 is facing the problem -- and without --max-import-depth=1 the test
times out at 10 minutes :O
We can't understand the real `six.py` file, so we have some internal plumbing
that enables us to handle six anyway. While updating that, I had a hell of a lot
of trouble with these tests.
What we actually want, is to see that we can understand what the values imported
from six are (i.e., their points-to information). I added a few more, that I
think would be useful. If we can figure out all of these, I don't actually care
if we're doing it by understanding the real `six.py` file, or by some internal
trick.
I verified that we don't get results with the real `six.py` file by disabling
our internal tricks, and putting a copy of six.py just next to test.py.
We used to have an other file that would list all the properties we knew and
their value, but that turned out to be a fragile and annoying test, since the
results differed from which version of python you ran it with (3.5 vs 3.8) and
which machine you ran it on (my machien vs jenkins). I don't care about the
results in this file, and I can certainly not eyeball it to see if it's correct
or not.
