The current method as the following problem, described by Sadra
Barikbin:
The tests that request both `pytester` and `monkeypatch` and use
`monkeypatch.chdir` without context, relying on `monkeypatch`'s teardown
to restore cwd. This doesn't work because the following sequence of
actions take place:
- `monkeypatch` is set up.
- `pytester` is set up. It saves the original cwd and changes it to a
new one dedicated to the test function.
- Test function calls `monkeypatch.chdir()` without context.
`monkeypatch` saves cwd, which is not the original one, before
changing it.
- `pytester` is torn down. It restores the cwd to the original one.
- `monkeypatch` is torn down. It restores cwd to what it has saved.
The solution here is to have pytester use `monkeypatch.chdir()` itself,
then everything is handled correctly.
This reverts commit e938580257.
Revert "improve error msg and test"
This reverts commit c0cf822ca1.
Revert "error msg"
This reverts commit ec1053cc16.
Revert "changelog"
This reverts commit d2dc8a70b5.
Revert "simplify code / take out user-gen typeerror case"
This reverts commit b9cb87d862.
In #10758 we introduced the support for the use of the walrus operator in the test cases. There was a case which was not handled that caused a bug report #11028. This PR aims to fix the issue and also to improve how the walrus operator is handled in the AssertionRewriter class.
Closes#11028
originally reproduced with this pollution set:
```
testing/test_assertrewrite.py::TestEarlyRewriteBailout::test_pattern_contains_subdirectories
testing/test_assertrewrite.py::TestRewriteOnImport::test_remember_rewritten_modules
```
Python 3.7 changes the pyc format by adding a flags byte. Even though it
is not necessary for us to match it, it is nice to be able to read pyc
files we emit for debugging the rewriter.
Update our custom pyc files to use that format. We write flags==0
meaning we still use the mtime+size format rather the newer hash format.
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.