While working on #130160 and #93096 it was decided that it would be worth paying attention to the problem of lack of tests for command line interface.

List of all cli modules is in the documentation: https://docs.python.org/dev/library/cmdline.html

Many modules are missing command line interface tests, so I suggest using this issue to submit PRs for now only for well-documented interfaces, for example:

• tokenize (gh-131178: Add tests for tokenize command-line interface #131274)
• platform (gh-131524: Update platform CLI to use argparse #131542)
• pickle (gh-131178: Add tests for pickle command-line interface #131275)
• ast (gh-131178: Add tests for ast command-line interface #133329)
• pickletools (gh-131178: Add tests for pickletools command-line interface #131287)
• http.server (gh-131178: Add tests for http.server command-line interface #132540)
• profile (gh-131178: Add CLI tests for profile module #134103)
• cProfile (gh-131178: Add CLI tests for cProfile #134269)
• site ( gh-131178: Add tests for site command-line interface  #133582)

TODO: Make sure all documented have tests for CLI (others are not so important as it has not been decided what to do with them yet)

You can use PR #127759 for dis module or #118132 for random module as a reference.
And I also suggest using subprocess.Popen to allocate a separate resource since some modules can block a lot of time.

Linked PRs

• gh-131178: Add tests for tokenize command-line interface #131274
• gh-131178: Add tests for pickle command-line interface #131275
• gh-131178: Add tests for pickletools command-line interface #131287
• gh-131178: Update help message for timeit CLI #131326
• gh-131178: Add tests for http.server command-line interface #132540
• gh-131178: Add tests for ast command-line interface #133329
• gh-131178: Add tests for site command-line interface  #133582
• gh-131178: Add CLI tests for profile module #134103
• gh-131178: fix SSL tests for http.server command-line interface #134224
• gh-131178: Add CLI tests for cProfile #134269
• gh-131178: add E2E mockless tests for http.server command-line interface #134279
• gh-131178: remove runtime tests for http.server CLI #134287
• gh-131178: Use support.captured_stdout and support.captured_stderr #137748
• gh-131178: Add tests for site command-line interface #137807
• gh-131178: Fix test_unknown_flag for platform CLI #137816
• [3.14] gh-131178: Add tests for site command-line interface (GH-133582) #137832
• [3.13] gh-131178: Add tests for site command-line interface (GH-133582) #137833
• gh-131178: Add tests for sysconfig command-line interface #139934
• gh-131178: add tests for filecmp command-line interface #139947
• gh-131178: add unittest for turtledemo #139983
• gh-131178: add tests for filecmp command-line interface #140199
• gh-131178: add tests for filecmp command-line interface #140200
• gh-131178: Add CLI tests for the profile module #143835
• gh-131178: Add tests for cProfile command-line interface #144918
• gh-131178: Add tests for pyclbr command-line interface #147995
• gh-131178: Add tests for mimetypes command-line interface #149681
• gh-131178: Fix mimetypes CLI docs to mention that errors go to stdout #149683
• gh-131178: Add tests for quopri command-line interface #149825
• gh-131178: Add more tests for json command-line interface #149868
• gh-131178: Add tests for zipapp command-line interface #150203
• [3.15] gh-131178: Fix mimetypes CLI docs, mention that errors go to stdout (GH-149683) #150655
• [3.14] gh-131178: Fix mimetypes CLI docs, mention that errors go to stdout (GH-149683) #150656
• gh-131178: Add tests for this command-line interface #151855
• gh-131178: Add CLI tests for pydoc module #151971