pytest-rerunfailures is a plugin for pytest that re-runs tests to eliminate intermittent failures.
You will need the following prerequisites in order to use pytest-rerunfailures:
- Python 3.7, up to 3.11, or PyPy3
- pytest 6.0 or newer
This plugin can recover from a hard crash with the following optional prerequisites:
- pytest-xdist 2.3.0 or newer
This package is currently tested against the last 5 minor pytest releases. In case you work with an older version of pytest you should consider updating or use one of the earlier versions of this package.
To install pytest-rerunfailures:
$ pip install pytest-rerunfailures
If one or more tests trigger a hard crash (for example: segfault), this plugin will ordinarily be unable to rerun the test. However, if a compatible version of pytest-xdist is installed, and the tests are run within pytest-xdist using the -n flag, this plugin will be able to rerun crashed tests, assuming the workers and controller are on the same LAN (this assumption is valid for almost all cases because most of the time the workers and controller are on the same computer). If this assumption is not the case, then this functionality may not operate.
To re-run all test failures, use the --reruns
command line option with the
maximum number of times you'd like the tests to run:
$ pytest --reruns 5
Failed fixture or setup_class will also be re-executed.
To add a delay time between re-runs use the --reruns-delay
command line
option with the amount of seconds that you would like wait before the next
test re-run is launched:
$ pytest --reruns 5 --reruns-delay 1
To re-run only those failures that match a certain list of expressions, use the
--only-rerun
flag and pass it a regular expression. For example,
the following would only rerun those errors that match AssertionError
:
$ pytest --reruns 5 --only-rerun AssertionError
Passing the flag multiple times accumulates the arguments, so the following
would only rerun those errors that match AssertionError
or ValueError
:
$ pytest --reruns 5 --only-rerun AssertionError --only-rerun ValueError
To re-run only those failures that do not match a certain list of expressions, use the
--rerun-except
flag and pass it a regular expression. For example,
the following would only rerun errors other than that match AssertionError
:
$ pytest --reruns 5 --rerun-except AssertionError
Passing the flag multiple times accumulates the arguments, so the following
would only rerun those errors that does not match with AssertionError
or OSError
:
$ pytest --reruns 5 --rerun-except AssertionError --rerun-except OSError
To mark individual tests as flaky, and have them automatically re-run when they
fail, add the flaky
mark with the maximum number of times you'd like the
test to run:
@pytest.mark.flaky(reruns=5)
def test_example():
import random
assert random.choice([True, False])
Note that when teardown fails, two reports are generated for the case, one for the test case and the other for the teardown error.
You can also specify the re-run delay time in the marker:
@pytest.mark.flaky(reruns=5, reruns_delay=2)
def test_example():
import random
assert random.choice([True, False])
You can also specify an optional condition
in the re-run marker:
@pytest.mark.flaky(reruns=5, condition=sys.platform.startswith("win32"))
def test_example():
import random
assert random.choice([True, False])
You can use @pytest.mark.flaky(condition)
similarly as @pytest.mark.skipif(condition)
, see pytest-mark-skipif
@pytest.mark.flaky(reruns=2,condition="sys.platform.startswith('win32')")
def test_example():
import random
assert random.choice([True, False])
# totally same as the above
@pytest.mark.flaky(reruns=2,condition=sys.platform.startswith("win32"))
def test_example():
import random
assert random.choice([True, False])
Note that the test will re-run for any condition
that is truthy.
Here's an example of the output provided by the plugin when run with
--reruns 2
and -r aR
:
test_report.py RRF ================================== FAILURES ================================== __________________________________ test_fail _________________________________ def test_fail(): > assert False E assert False test_report.py:9: AssertionError ============================ rerun test summary info ========================= RERUN test_report.py::test_fail RERUN test_report.py::test_fail ============================ short test summary info ========================= FAIL test_report.py::test_fail ======================= 1 failed, 2 rerun in 0.02 seconds ====================
Note that output will show all re-runs. Tests that fail on all the re-runs will be marked as failed.
- This plugin may not be used with class, module, and package level fixtures.
- This plugin is not compatible with pytest-xdist's --looponfail flag.
- This plugin is not compatible with the core --pdb flag.
Test execution count can be retrieved from the
execution_count
attribute in testitem
's object. Example:@hookimpl(tryfirst=True) def pytest_runtest_makereport(item, call): print(item.execution_count)