@pytest.mark.focus

pytest vresion 5.3.0

I would like to have a feature where I can say “run only this test” from the source file without needing to open any other file or modify any command-line script.

A possible solution is to have a unique marker, e.g. @pytest.mark.focus that would allow me to achieve a similar effect to -m MARKEXPR, but with two changes:

• when no test is marked with it, then run all tests,
• don’t need to specify it on the command line.

There are multiple use-cases where it would be beneficial:

• My specific use-case: In my local development, when writing python code, I have a script running on my command line that watches file changes, and whenever a file is modified, the script automatically re-runs pytest. Having @pytest.mark.focus allows me to very quickly focus on a specific test: add decorator + hit save button. I don’t have to look for .sh file, modify it…
• Another use case: When the pytest command is wrapped in another script/tool, and it is not possible or hard to pass command-line options to pytest.

Possible implementation (by @godlygeek):

import pytest

def pytest_collection_modifyitems(items):
    '''If any items are marked 'focus', run only those items.

    This hook is run automatically by pytest.
    '''
    # Find items with the 'focus' mark
    focused = [item for item in items if item.get_closest_marker("focus")]
    # If any have it, replace the full list of collected items with only them
    if focused:
        items[:] = focused

def pytest_configure(config):
    config.addinivalue_line(
        "markers", "focus: If any tests have this mark, run only those"
    )

Alternative implementation: add a command line option --run-all-if-none-marked, but with a better name.

I believe this feature seems simple and useful enough to be added to pytest directly and not to be a plugin.

[The-Compiler]

FWIW there’s already the pytest-only plugin which does that.

[fkondej]

@RonnyPfannschmidt thank you for clarification. I looked for this kind of information, before creating this ticket, but I have missed it. Do you think it is worth to try this concept in core now? The pytest-only plugin looks mature to me.

I will use the plugin for now and wait for it to be added to the core.