[Python-Dev] Problems with regrtest and with logging (original) (raw)

Éric Araujo merwok at netwok.org
Mon May 9 18:42:06 CEST 2011

Hi,

When it comes to containers, identity matters at least as much as value does (and sometimes more so - e.g. sys.modules). Replacing those global containers with new ones isn't guaranteed to work, as they may be cached in various places rather than always retrieved fresh from the relevant module namespace. Modifying them in place, on the other hand, does the right thing even in the presence of cached references.

That makes sense, thanks for the explanation!

A comment to that effect may be a useful addition to regrtest, as I expect others may have similar questions about those identity checks in the future. (It may even be a useful addition to the documentation, but I have no idea where it could be sensibly included).

Somewhere in unittest doc, say in the section about tearDown. Or maybe it’s time for a Python testing best practices howto?

Also, don't be surprised if wholesale cleanup like that isn't completely reliable - it's far, far better if the test case understands the changes it is making (even indirectly) and explicitly reverses them.

Yep, I was probably bringing out the big guns too early.
self.addCleanup(sys.path.remove, path) is better and even shorter than my previous code!

Cheers

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