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
There are a few things I missed in gh-27980. This is a follow-up that will make subsequent PRs cleaner. It includes fixes to tests and tools that reference the frozen modules.
https://bugs.python.org/issue45019
Add frozen modules to sys.stdlib_module_names. For example, add
"_frozen_importlib" and "_frozen_importlib_external" names.
Add "list_frozen" command to Programs/_testembed.