pytest-sherlock

Pytest plugin which help to find coupled tests.

Sometimes we have coupled tests which depend from ordering

For example:

• PASSES tests/exmaple/test_all_read.py tests/exmaple/test_b_modify.py tests/exmaple/test_c_delete.py
• FAILED tests/exmaple/test_c_delete.py tests/exmaple/test_b_modify.py tests/exmaple/test_all_read.py

In this case pretty simple to detect coupled tests, but if we have >=1k tests which called before it will hard

Content:

• install
• how to use
• waiting in the future

Install

pip install pytest-sherlock

how to use:

pytest tests/exmaple/test_c_delete.py tests/exmaple/test_b_modify.py tests/exmaple/test_all_read.py --flaky-test="test_read_params" -vv

Plugin didn't run all tests, it try to find some possible guilty test and will run first

Try to find coupled tests in [3-4] steps
__________________________ Step [1 of 4]: __________________________

tests/exmaple/test_c_delete.py::test_delete_random_param PASSED                                                                                                      [ 20%]
tests/exmaple/test_b_modify.py::test_modify_random_param PASSED                                                                                                      [ 40%]
tests/exmaple/test_c_delete.py::test_deleted_passed PASSED                                                                                                           [ 60%]
tests/exmaple/test_c_delete.py::test_do_not_delete PASSED                                                                                                            [ 80%]
tests/exmaple/test_all_read.py::test_read_params FAILED                                                                                                             [100%]
__________________________ Step [2 of 4]: __________________________

tests/exmaple/test_c_delete.py::test_delete_random_param PASSED                                                                                                      [ 33%]
tests/exmaple/test_b_modify.py::test_modify_random_param PASSED                                                                                                      [ 66%]
tests/exmaple/test_all_read.py::test_read_params FAILED                                                                                                             [100%]
__________________________ Step [3 of 4]: __________________________

tests/exmaple/test_c_delete.py::test_delete_random_param PASSED                                                                                                      [ 50%]
tests/exmaple/test_all_read.py::test_read_params PASSED                                                                                                              [100%]
__________________________ Step [4 of 4]: __________________________

tests/exmaple/test_b_modify.py::test_modify_random_param PASSED                                                                                                      [ 50%]
tests/exmaple/test_all_read.py::test_read_params FAILED                                                                                                             [100%]

============================== FAILURES ==============================
__________________________ test_read_params __________________________

Found coupled tests:
tests/exmaple/test_b_modify.py::test_modify_random_param
tests/exmaple/test_all_read.py::test_read_params

Common fixtures:
config

How to reproduce:
pytest -l -vv tests/exmaple/test_b_modify.py::test_modify_random_param tests/exmaple/test_all_read.py::test_read_params


AssertionError: assert 13 == 2
 +  where 13 = <built-in method get of dict object at 0x102664280>('b')
 +    where <built-in method get of dict object at 0x102664280> = {'a': 1, 'b': 13, 'c': 3}.get

tests/exmaple/test_all_read.py:8: AssertionError
=================== 1 failed, 9 passed in 0.08 seconds ===================

The plugin also supports --lf (last failed) option to rerun found coupled tests. It allows us to make sure that coupled tests are true.

pytest tests/exmaple/test_c_delete.py tests/exmaple/test_b_modify.py tests/exmaple/test_all_read.py --lf

=========================================================================== test session starts ============================================================================
platform darwin -- Python 3.7.10, pytest-3.5.1, py-1.7.0, pluggy-0.6.0
collected 10 items / 8 deselected
run-last-failure: rerun previous 2 failures

tests/exmaple/test_b_modify.py .                                                                                                                                     [ 50%]
tests/exmaple/test_all_read.py F                                                                                                                                     [100%]

================================================================================= FAILURES =================================================================================
_____________________________________________________________________________ test_read_params _____________________________________________________________________________

config = {'a': 1, 'b': 13, 'c': 3}, param = 'b'

    def test_read_params(config, param):
>       assert config.get(param) == 2
E       AssertionError: assert 13 == 2
E        +  where 13 = <built-in method get of dict object at 0x10c964cd0>('b')
E        +    where <built-in method get of dict object at 0x10c964cd0> = {'a': 1, 'b': 13, 'c': 3}.get

tests/exmaple/test_all_read.py:6: AssertionError
============================================================= 1 failed, 1 passed, 8 deselected in 0.05 seconds =============================================================

TODO

I have a couple ideas, how to improve finder coupled tests:

• use AST for detect common peace of code (variables, functions, etc...)