pytest-matcher 1.5.1

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What is this

This is a pytest plugin which provides a couple of fixtures to match test output against patterns stored in files.

The plugin extends pytest with the following CLI options:

• --pm-save-patterns – to store the output to a pattern file (instead of checking);

• --pm-patterns-base-dir to specify a base directory, where to lookup pattern files.

Pattern files are stored in a base directory and additional paths based on test module name, test class name and/or test function name as following:

<base-dir>/<test-module-name>/[test-class-name/]<test-function-name>[[<callspec-id>]]

Note, that for non-class test functions the test-class-name part is absent. For parametrized tests, the callspec-id part containing %XX-escaped information about the parametrization is added.

Quick Start

The plugin provides expected_out and expected_err named fixture functions.

def test_foo(capfd, expected_out):
    print('foo')

    stdout, stderr = capfd.readouterr()

    assert stdout == expected_out

Add pm-patterns-base-dir option to pytest.ini file (and pytest section) pointing for example to test/data/expected. For the first pytest run it would fail, cuz there is no expected pattern file present. To write it one can use pytest CLI:

$ pytest --pm-save-patterns test/test_foo.py::test_foo

Review the stored pattern file and add to your VCS.

See Also

• How it works