Assertion rewrite should match files completely and avoid rewriting setup.py

[nicoddemus]

Quoting @hroncok in pypa/setuptools#1170:

• _pytest.config._mark_plugins_for_rewrite should not register setup when it sees setup.py
• _pytest.assertion.rewrite._should_rewrite should probably match things that startswith mark + '.', not just mark (although I'm not very sure here)

[hroncok]

Ad _should_rewrite: when I think about it, it should either be exact match or it should start with the thing plus dot.

[nicoddemus]

Heh exactly what I came up with. 😁

I will open a PR shortly.

[nicoddemus]

diff --git a/_pytest/assertion/rewrite.py b/_pytest/assertion/rewrite.py
index d48b664..27026b0 100644
--- a/_pytest/assertion/rewrite.py
+++ b/_pytest/assertion/rewrite.py
@@ -168,7 +168,7 @@ class AssertionRewritingHook(object):
                 return True

         for marked in self._must_rewrite:
-            if name.startswith(marked):
+            if name == marked or name.startswith(marked + '.'):
                 state.trace("matched marked file %r (from %r)" % (name, marked))
                 return True

😉

I'm finishing up the test.

[hroncok]

Note that blacklisting setup.py from _pytest.config._mark_plugins_for_rewrite is not needed anymore to fix this particular problem, but I'd still rather do it, because having it there can bring other problems some day.

[nicoddemus]

Hmm not sure about setup.py now, I've seen code in the wild which used setup.py, although usually inside packages so this probably wouldn't be an issue. Let's see if others have an opinion on this.

[hroncok]

Ok, not blacklist it, but reconsider the code that produces it as it's result for sdist installed packages. (I cannot reopen, not my issue)

[nicoddemus]

I see, it makes sense to ignore setup.py files that are declared in the root of the metadata. Created #2941 for that. 👍