homepage

Extract of test.libregrtest.setup_tests():
 for module in sys.modules.values():
 if hasattr(module, '__path__'):
 module.__path__ = [os.path.abspath(path)
 for path in module.__path__]
 if hasattr(module, '__file__'):
 module.__file__ = os.path.abspath(module.__file__)
Because of this code, it's not possible to store test files outside Lib/test/. For the issue #26295 (test_regrtest), I would like to create a temporary directory and then a subdirectory test/ to create temporary test files.
Attached patch adds _NamespacePath.__setitem__() method and modify setup_tests() to keep the _NamespacePath type of module.__path__.
Maybe we should move this abspath() code somewhere in importlib. The site module already contains similar code, abs_paths() function:
 for m in set(sys.modules.values()):
 if (getattr(getattr(m, '__loader__', None), '__module__', None) not in
 ('_frozen_importlib', '_frozen_importlib_external')):
 continue # don't mess with a PEP 302-supplied __file__
 try:
 m.__file__ = os.path.abspath(m.__file__)
 except (AttributeError, OSError):
 pass
 try:
 m.__cached__ = os.path.abspath(m.__cached__)
 except (AttributeError, OSError):
 pass
Since this code looks to depend on the implementation of importlib (the __loader__ test), IMHO it makes sense to move the code directly somewhere in importlib.