Sharing fixtures with conftest.py files

Suppose we need to use our comedy_series fixture from the previous section in other test modules. In pytest, sharing fixtures is easily done by just moving the fixture code to a conftest.py file.

A conftest.py file is a normal Python module, except that it is loaded automatically by pytest, and any fixtures defined in it are available to test modules in the same directory and below automatically. Consider this test module hierarchy:

tests/
    ratings/
        series.csv
        test_ranking.py
    io/
        conftest.py
        test_formats.py 
    conftest.py

The tests/conftest.py file is at the root of the hierarchy, so any fixtures defined on it are automatically available to all other test modules in this project. Fixtures in tests/io/conftest.py will be available only to modules at and below tests/io, so only to test_formats.py for now.

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