A pytest plugin to trace resource leaks.
leaks:
-R LEAKS, --leaks=LEAKS
runs each test several times and examines
sys.gettotalrefcount() to see if the test appears to
be leaking references. The argument should be of the
form stab:run where 'stab' is the number of times the
test is run to let gettotalrefcount settle down, 'run'
is the number of times further it is run. These
parameters all have defaults (5 and 4, respectively),
and the minimal invocation is '-R :'.
To add a leaks test to your py.test session, add the -R option on the
command line:
$ python3-debug -mpytest -v -R : examples/test_faucet.py
=========================== test session starts ===========================
platform linux -- Python 3.7.5, pytest-5.3.1, py-1.8.0, pluggy-0.13.1 -- .
cachedir: .pytest_cache
rootdir: .
plugins: leaks-0.3.1
collected 4 items
examples/test_faucet.py::test_leaky_faucet LEAKED [ 25%]
examples/test_faucet.py::test_broken_faucet FAILED [ 50%]
examples/test_faucet.py::test_mended_faucet PASSED [ 75%]
examples/test_faucet.py::test_skip_marker_example LEAKED [100%]
================================ FAILURES =================================
___________________________ test_broken_faucet ____________________________
def test_broken_faucet():
> assert 0
E assert 0
examples/test_faucet.py:8: AssertionError
============================== leaks summary ==============================
examples/test_faucet.py::test_leaky_faucet: leaked references: [2, 2, 2, 2], memory blocks: [2, 2, 2, 2]
examples/test_faucet.py::test_skip_marker_example: leaked (not checked): 'not testing'
================== 1 failed, 1 passed, 2 leaked in 0.50s ==================
Note that a debug build of Python must be used. The test file used above contains the following code:
$ cat test_faucet.py
import pytest
drops = []
def test_leaky_faucet():
drops.append({})
def test_broken_faucet():
assert 0
def test_mended_faucet():
assert 1
@pytest.mark.no_leak_check(fail=True, reason="not testing")
def test_skip_marker_example():
pass
Note that pytest-leaks runs tests several times: if you see test failures that are present only when using pytest-leaks, check that the test does not modify any global state in a way that prevents it from running a second time.
- Detects memory leaks by running py.test tests repeatedly and comparing total reference counts between the runs.
- py.test version >= 3;
- A debug build of Python (2.7 or >=3.5).
On Linux, Python debug builds can be found in packages pythonX.Y-dbg
(Debian and derivatives) and python3-debug (Fedora and derivatives).
You can install "pytest-leaks" via pip from PyPI:
$ pip install pytest-leaks
Contributions are very welcome. Tests can be run with tox, please ensure the coverage at least stays the same before you submit a pull request.
Distributed under the terms of the MIT and PSF licenses, "pytest-leaks" is free and open source software.
If you encounter any problems, please file an issue along with a detailed description.