Closed
Description
Recently, I had a workshop about parametric tests and fixtures in pytest. As one of the examples I tried to use the capsys fixture inside my own and failed. I wonder if it's a bug or documented behavior I couldn't find.
First, working code
def test_print(capsys):
print(123, 456, 789)
out, err = capsys.readouterr()
assert not err.strip()
assert '5' in out$ python -m pytest demo.py
... 1 passed in 0.01 seconds ...Broken code
Now I don't like multiple assertions in one test, so let's create a fixture and split it:
import pytest
OUT = 0
ERR = 1
@pytest.fixture
def captured_print(capsys):
print(123, 456, 789)
out, err = capsys.readouterr()
return out.strip(), err.strip()
def test_print_no_stderr(captured_print):
assert not captured_print[ERR]
def test_print_stdout_contains_5(captured_print):
assert '5' in captured_print[OUT]I think this should work. At least, it feels like a natural way of doing it. But it blows up:
$ python -m pytest demo.py
... AttributeError: 'CaptureFixture' object has no attribute '_capture' ...Full output
============================= test session starts ==============================
platform linux -- Python 3.6.2, pytest-3.2.2.dev17+g539523cf, py-1.4.34, pluggy-0.4.0
rootdir: /home/churchyard/Dokumenty/pytest, inifile: tox.ini
collected 2 items
demo.py EE
==================================== ERRORS ====================================
____________________ ERROR at setup of test_print_no_stderr ____________________
self = <_pytest.capture.CaptureFixture object at 0x7fe560f30c50>
def readouterr(self):
try:
> return self._capture.readouterr()
E AttributeError: 'CaptureFixture' object has no attribute '_capture'
../_pytest/capture.py:208: AttributeError
During handling of the above exception, another exception occurred:
capsys = <_pytest.capture.CaptureFixture object at 0x7fe560f30c50>
@pytest.fixture
def captured_print(capsys):
print(123, 456, 789)
> out, err = capsys.readouterr()
demo.py:10:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <_pytest.capture.CaptureFixture object at 0x7fe560f30c50>
def readouterr(self):
try:
return self._capture.readouterr()
except AttributeError:
> return self._outerr
E AttributeError: 'CaptureFixture' object has no attribute '_outerr'
../_pytest/capture.py:210: AttributeError
---------------------------- Captured stdout setup -----------------------------
123 456 789
________________ ERROR at setup of test_print_stdout_contains_5 ________________
self = <_pytest.capture.CaptureFixture object at 0x7fe560f6a358>
def readouterr(self):
try:
> return self._capture.readouterr()
E AttributeError: 'CaptureFixture' object has no attribute '_capture'
../_pytest/capture.py:208: AttributeError
During handling of the above exception, another exception occurred:
capsys = <_pytest.capture.CaptureFixture object at 0x7fe560f6a358>
@pytest.fixture
def captured_print(capsys):
print(123, 456, 789)
> out, err = capsys.readouterr()
demo.py:10:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <_pytest.capture.CaptureFixture object at 0x7fe560f6a358>
def readouterr(self):
try:
return self._capture.readouterr()
except AttributeError:
> return self._outerr
E AttributeError: 'CaptureFixture' object has no attribute '_outerr'
../_pytest/capture.py:210: AttributeError
---------------------------- Captured stdout setup -----------------------------
123 456 789
=========================== 2 error in 0.06 seconds ============================
System information
$ python --version
Python 3.6.2
$ pip freeze
py==1.4.34
-e git://github.com/pytest-dev/pytest.git@539523cfee4c49a765569abcf68134b1255eedb5#egg=pytest
# also happens on 3.2.1
$ uname
Linux
$ uname -m
x86_64
$ head -n2 /etc/os-release
NAME=Fedora
VERSION="26 (Twenty Six)"