How does pytest identify and fail to identify modules for testing?

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Pytest identifies modules for testing by searching for files and directories that match a specific naming convention, such as files starting with "test" or directories named "tests". Once it finds potential test files, it looks for functions with names starting with "test" or marked with the "@pytest.mark.test" decorator.

Pytest may fail to identify modules for testing if they do not follow the naming convention or if they are not located in a folder with the word "test" in the name. Additionally, pytest may not recognize test functions if they are spelled incorrectly or do not have the appropriate name or decorator. It is important to follow the naming conventions and properly label test functions to ensure they are identified and run by pytest.