This makes mypy raise an error whenever it detects code which is
statically unreachable, e.g.
x: int
if isinstance(x, str):
... # Statement is unreachable [unreachable]
This is really neat and finds quite a few logic and typing bugs.
Sometimes the code is intentionally unreachable in terms of types, e.g.
raising TypeError when a function is given an argument with a wrong
type. In these cases a `type: ignore[unreachable]` is needed, but I
think it's a nice code hint.
This prevents referring to a generic type without filling in its generic
type parameters.
The FixtureDef typing might need some more refining in the future.
In Python, if module A defines a name `name`, and module B does `import
name from A`, then another module C can `import name from B`.
Sometimes it is intentional -- module B is meant to "reexport" `name`.
But sometimes it is just confusion/inconsistency on where `name` should
be imported from.
mypy has a flag `--no-implicit-reexport` which puts some order into
this. A name can only be imported from a module if
1. The module defines the name
2. The module's `__all__` includes the name
3. The module imports the name as `from ... import .. as name`.
This flag is included in mypy's `--strict` flag.
I like this flag, but I realize it is a bit controversial, and in
particular item 3 above is a bit unfriendly to contributors who don't
know about it. So I didn't intend to add it to pytest.
But while investigating issue 7589 I came upon mypy issue 8754 which
causes `--no-implicit-reexport` to leak into installed libraries and
causes some unexpected typing differences *in pytest* if the user uses
this flag.
Since the diff mostly makes sense, let's just conform to it.
We barely use it; the couple places that do are not really worth the
extra dependency, I think the code is clearer without it.
Also simplifies one (regular) itertools usage.
Also improves a check and an error message in `pytest.raises`.
Part of the effort to reduce dependency on the py library.
Besides that, py.xml implements its own XML serialization which is
pretty scary.
I tried to keep the code with minimal changes (though it could use some
cleanups). The differences in behavior I have noticed are:
- Attributes in the output are not sorted.
- Some unneeded escaping is no longer performed, for example escaping
`"` to `"` in a text node.
1. Remove sys.maxunicode check & comment. Nowadays it is always a
constant 0x10ffff.
2. Pre-generate the pattern. Possible due to 1.
3. Compile the regex lazily. No reason to pay startup cost for it.
4. Add docstring in particular to explain a subtle point.
`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.
