* Fix patch.object to return a _patch context manager.
This should fix https://github.com/python/typeshed/issues/914
* Prefer None over ... to be consistent with the rest of the file.
This declares the method to take the union of Set and FrozenSet
rather than AbstractSet since that is where `difference()`
(used by `assertSetEqual()`) is defined.
The stubs for `unittest.TestCase.assertCountEqual()` specify the parameters are Sequences; in fact the method works fine with Iterables, as the first thing the method does is convert them to lists. [1] The docs do say sequences, but it appears there is no reason they cannot be Iterables.
[1]: https://github.com/python/cpython/blob/master/Lib/unittest/case.py#L1156
According to the documentation in the typing module, TypeVars cannot
have only a single constraint. Attempting to do so will actually result
in an exception at runtime. (However, this error is currently ignored
by mypy -- see https://github.com/python/mypy/pull/2626 for a related
pending pull request).
This commit changes all instances of TypeVars using a single constraint
(e.g. `T = TypeVar('T', Foo)`) to use bounds instead (e.g.
`T = TypeVar('T', bound=Foo)`.
This seems to be the correct fix for plistlib after reading the module
docs, but it's less obvious this is correct for unittest. The unittest
module originally had `_FT = TypeVar('_FT', Callable[[Any], Any])` -- an
alternative fix would have been to do `_FT = Callable[[Any], Any]`.
Although I'm not entirely sure what it means to have a bound be a
Callable, I decided to make the assumption that the original authors
probably meant to use TypeVars instead of type aliases for a reason
(possibly to handle classes implementing `__call__`?)
