Add tests for command-line interface

[donBarbos]

While working on #130160 and #93096 I thought 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-131274)
• platform (gh-131524: Update platform CLI to use argparse #131542)
• pickle (gh-131275)
• pickletools (gh-131287)
• http.server

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.

Important

For those who want to work on the issue, please:

• Select one module for which tests will be improved. It's easier to review and backport.
• Open a pull request with the following title: gh-131178: Add tests for `MODULE_NAME` command-line interface

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

[hugovk]

See also the tests added in #118132, based on https://pythontest.com/testing-argparse-apps/

[sobolevn]

@donBarbos I assigned this issue to you, since you mentioned that you are working on it :)