`os.scandir()`, introduced in Python 3.5, is much faster than
`os.listdir()`. See https://www.python.org/dev/peps/pep-0471/.
It also has a `DirEntry` which can be used to further reduce syscalls in
some cases.
Part of reducing dependency on `py`. Also enables upcoming improvements.
In cases where there are simpler alternatives (in tests), I used those.
What's left are a couple of uses in `_pytest.main` and `_pytest.python`
and they only have modest requirements, so all of the featureful code
from py is not needed.
The previous typing had an object passed to the user, which they can't
do anything with without asserting, which is inconvenient. Change it to
Any instead.
Note that what comes *back* to pytest (the return value) should be an
`object`, because we want to handle arbitrary objects without assuming
anything about them.
If a test runtest phase (not setup) dynamically adds a pytest.mark.xfail
mark to the item, it should be respected, but it wasn't. This regressed
in 3e6fe92b7e (not released).
Fix it by just always refreshing the mark if needed. This is mostly what
was done before but in a more roundabout way.
eval() is used for evaluating string conditions in skipif/xfail e.g.
@pytest.mark.skipif("1 == 0")
This is the only code that uses `_pytest._code.compile()`, so removing
its last use enables us to remove it entirely.
In this case it doesn't add much. Plain compile() gives a good enough
error message.
For regular exceptions, the message is the same.
For SyntaxError exceptions, e.g. "1 ==", the previous code adds a little
bit of useful context:
```
invalid syntax (skipping.py:108>, line 1)
The above exception was the direct cause of the following exception:
1 ==
^
(code was compiled probably from here: <0-codegen /pytest/src/_pytest/skipping.py:108>) (line 1)
During handling of the above exception, another exception occurred:
Error evaluating 'skipif' condition
1 ==
^
SyntaxError: invalid syntax
```
The new code loses it:
```
unexpected EOF while parsing (<skipif condition>, line 1)
During handling of the above exception, another exception occurred:
Error evaluating 'skipif' condition
1 ==
^
SyntaxError: invalid syntax
```
Since the old message is a minor improvement to an unlikely error
condition in a deprecated feature, I think it is not worth all the code
that it requires.
