Add --start-at/after options to runtests.py

[Marten Kenbeek]

When making changes that affect large parts of Django, there can often be a lot of test failures. I commonly use the --failfast option to tackle these one at a time. After encountering a test failure, I want to do one of two things:

• Fix the error and test again.
• Skip the error and look for the next one.

In both cases you often have to rerun a large part of the test suite of which you are fairly certain it passes, which can take a lot of time. In the second case you either have to remove --failfast and manually check for errors, or mark the test as an expected failure or skipped test.

I propose to add two options to Django's internal test suite, --start-at and --start-after. Both allow you to specify a top-level module where the test suite should start running tests. --start-at includes the specified module, --start-after excludes it.

[Marten Kenbeek]

​PR

[Tim Graham]

A note in docs/internals/contributing/writing-code/unit-tests.txt would be useful.

[Mariusz Felisiak <felisiak.mariusz@…>]

In ef7e0ae5:

Refs #28520 -- Added _module_match_label() hook to runtests.py.

[Mariusz Felisiak <felisiak.mariusz@…>]

In e2de49ec:

Fixed #28520 -- Added --start-at/--start-after options to runtests.py.