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https://github.com/box/flaky

Plugin for nose or pytest that automatically reruns flaky tests.
https://github.com/box/flaky

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Plugin for nose or pytest that automatically reruns flaky tests.

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flaky

=====



.. image:: http://opensource.box.com/badges/stable.svg

    :target: http://opensource.box.com/badges



.. image:: https://github.com/box/flaky/actions/workflows/tox.yml/badge.svg?branch=master&event=push

    :target: https://github.com/box/flaky/actions/workflows/tox.yml



.. image:: https://img.shields.io/pypi/v/flaky.svg

    :target: https://pypi.python.org/pypi/flaky



About

-----



Flaky is a plugin for pytest that automatically reruns flaky tests.



Ideally, tests reliably pass or fail, but sometimes test fixtures must rely on components that aren't 100%

reliable. With flaky, instead of removing those tests or marking them to @skip, they can be automatically

retried.



For more information about flaky, see `this presentation `_.



Marking tests flaky

~~~~~~~~~~~~~~~~~~~



To mark a test as flaky, simply import flaky and decorate the test with @flaky:



.. code-block:: python



    from flaky import flaky



.. code-block:: python



    @flaky

    def test_something_that_usually_passes(self):

        value_to_double = 21

        result = get_result_from_flaky_doubler(value_to_double)

        self.assertEqual(result, value_to_double * 2, 'Result doubled incorrectly.')



By default, flaky will retry a failing test once, but that behavior can be overridden by passing values to the

flaky decorator. It accepts two parameters: max_runs, and min_passes; flaky will run tests up to max_runs times, until

it has succeeded min_passes times. Once a test passes min_passes times, it's considered a success; once it has been

run max_runs times without passing min_passes times, it's considered a failure.



.. code-block:: python



    @flaky(max_runs=3, min_passes=2)

    def test_something_that_usually_passes(self):

        """This test must pass twice, and it can be run up to three times."""

        value_to_double = 21

        result = get_result_from_flaky_doubler(value_to_double)

        self.assertEqual(result, value_to_double * 2, 'Result doubled incorrectly.')



Marking a class flaky

+++++++++++++++++++++



In addition to marking a single test flaky, entire test cases can be marked flaky:



.. code-block:: python



    @flaky

    class TestMultipliers(TestCase):

        def test_flaky_doubler(self):

            value_to_double = 21

            result = get_result_from_flaky_doubler(value_to_double)

            self.assertEqual(result, value_to_double * 2, 'Result doubled incorrectly.')



        @flaky(max_runs=3)

        def test_flaky_tripler(self):

            value_to_triple = 14

            result = get_result_from_flaky_tripler(value_to_triple)

            self.assertEqual(result, value_to_triple * 3, 'Result tripled incorrectly.')



The @flaky class decorator will mark test_flaky_doubler as flaky, but it won't override the 3 max_runs

for test_flaky_tripler (from the decorator on that test method).



Pytest marker

+++++++++++++



When using ``pytest``, ``@pytest.mark.flaky`` can be used in place of ``@flaky``.



Don't rerun certain types of failures

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Depending on your tests, some failures are obviously not due to flakiness. Instead of rerunning

after those failures, you can specify a filter function that can tell flaky to fail the test right away.



.. code-block:: python



    def is_not_crash(err, *args):

        return not issubclass(err[0], ProductCrashedError)



    @flaky

    def test_something():

        raise ProductCrashedError



    @flaky(rerun_filter=is_not_crash)

    def test_something_else():

        raise ProductCrashedError



Flaky will run ``test_something`` twice, but will only run ``test_something_else`` once.



It can also be used to incur a delay between test retries:



.. code-block:: python

    

    import time

    

    def delay_rerun(*args):

        time.sleep(1)

        return True

    

    @flaky(rerun_filter=delay_rerun)

    def test_something_else():

        ...



Activating the plugin

~~~~~~~~~~~~~~~~~~~~~



With pytest, flaky will automatically run. It can, however be disabled via the command line:



.. code-block:: console



    pytest -p no:flaky



Command line arguments

~~~~~~~~~~~~~~~~~~~~~~



No Flaky Report

+++++++++++++++



Pass ``--no-flaky-report`` to suppress the report at the end of the run detailing flaky test results.



Shorter Flaky Report

++++++++++++++++++++



Pass ``--no-success-flaky-report`` to suppress information about successful flaky tests.



Force Flaky

+++++++++++



Pass ``--force-flaky`` to treat all tests as flaky.



Pass ``--max-runs=MAX_RUNS`` and/or ``--min-passes=MIN_PASSES`` to control the behavior of flaky if ``--force-flaky``

is specified. Flaky decorators on individual tests will override these defaults.



*Additional usage examples are in the code - see test/test_pytest/test_pytest_example.py*



Installation

------------



To install, simply:



.. code-block:: console



    pip install flaky



Compatibility

-------------



Flaky is tested with the following test runners and options:



- Py.test. Works with ``pytest-xdist`` but not with the ``--boxed`` option. Doctests cannot be marked flaky.



Contributing

------------



See `CONTRIBUTING.rst `_.



Setup

~~~~~



Create a virtual environment and install packages -



.. code-block:: console



    mkvirtualenv flaky

    pip install -r requirements-dev.txt



Testing

~~~~~~~



Run all tests using -



.. code-block:: console



    tox



The tox tests include code style checks via pycodestyle and pylint.



Copyright and License

---------------------



::



 Copyright 2015 Box, Inc. All rights reserved.



 Licensed under the Apache License, Version 2.0 (the "License");

 you may not use this file except in compliance with the License.

 You may obtain a copy of the License at



    http://www.apache.org/licenses/LICENSE-2.0



 Unless required by applicable law or agreed to in writing, software

 distributed under the License is distributed on an "AS IS" BASIS,

 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 See the License for the specific language governing permissions and

 limitations under the License.