I've added a number of test-only modules. Some of those cases are covered by the recently frozen stdlib modules (and some will be once we add encodings back in). However, I figured we'd play it safe by having a set of modules guaranteed to be there during tests.
https://bugs.python.org/issue45020
Here's one more small cleanup that should have been in PR gh-28319. We eliminate stdout side-effects from importing the frozen __hello__ module, and update tests accordingly. We also move the module's source file into Lib/ from Toos/freeze/flag.py.
https://bugs.python.org/issue45019
Currently we freeze several modules into the runtime. For each of these modules it is essential to bootstrapping the runtime that they be frozen. Any other stdlib module that we later freeze into the runtime is not essential. We can just as well import from the .py file. This PR lets users explicitly choose which should be used, with the new "-X frozen_modules=[on|off]" CLI flag. The default is "off" for now.
https://bugs.python.org/issue45020
Adds `load_package_tests` function to test.support, uses it in test_asyncio,
test_email, test_json, test_tools, test_importlib and all test_importlib
sub-packages to implement test discovery.
Previously __path__ was set to [__name__], but that could lead to bad
results if someone managed to circumvent the frozen importer and
somehow ended up with a finder that thought __name__ was a legit
directory/location.
