When assertions fail inside a test, contextmanagers don't work

[parantapa]

Description of the bug

When assertions fail inside a test, context managers don't work.

Test code

from contextlib import contextmanager
@contextmanager
def hello():
    print("this runs")
    yield
    print("this doesn't run")

def test_hello():
    with hello():
        assert 1 == 0

Running the above code with pytest -s yields

> pytest -s
======================== test session starts ========================
platform linux -- Python 3.6.4, pytest-3.5.0, py-1.5.3, pluggy-0.6.0
rootdir: /home/parantapa/workspace/pytest_test, inifile:
collected 1 item                                                    

test_basic.py this runs
F

============================= FAILURES ==============================
____________________________ test_hello _____________________________

    def test_hello():
        with hello():
>           assert 1 == 0
E           assert 1 == 0

test_basic.py:11: AssertionError
===================== 1 failed in 0.03 seconds ======================

pip list of the virtual environment

pip list
attrs (17.4.0)
more-itertools (4.1.0)
pip (9.0.3)
pluggy (0.6.0)
py (1.5.3)
pytest (3.5.0)
setuptools (39.0.1)
six (1.11.0)
wheel (0.31.0)

pytest and operating system versions

pytest=3.5.0, python=3.6, OS=ArchLinux

[pytestbot]

GitMate.io thinks possibly related issues are #2121 (Test assertions does not work properly when specifying python_files setting), #747 (flakes test fail), #662 (fail on zero tests found), #1777 (sigalrm fails test), and #2172 (Capturing output causes test to fail.).

[nicoddemus]

For the code block after yield to execute in case of an exception you need to surround it with try/except:

from contextlib import contextmanager
@contextmanager
def hello():
    print("this runs")
    try:
        yield
    finally:
        print("this doesn't run")

def test_hello():
    with hello():
        assert 1 == 0

This is how @contextmanager works and not really related to pytest.

[RonnyPfannschmidt]

closing as this one is entirely about core python behaviour