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How to force pytest to read options from commandline only, and ignore config files?

Suppose the pytest config file pyproject.toml is in the project directory:
[tool.pytest.ini_options]
addopts = "-rap --capture=tee-sys"
I usually use the options in this file when running the command pytest. And the options are automatically read from the file.
However, sometimes I want to run pytest with -rA only:
pytest -rA # it becomes: pytest -rA --capture=tee-sys
I have to run it with: pytest -rA --capture=fd to override the option --capture=tee-sys in the config file.
Is there any way to force pytest to read options from commandline only?
What I've tried:
In #Andrei 's answer of this question: Is there an option for pytest to ignore the setup.cfg file?
Use -c /dev/null will prevent pytest from finding the config file. I also find that set -c any-non-exist-path is ok.
However, I'm afraid if -c /dev/null has side effects. In pytest docs (https://docs.pytest.org/en/latest/reference/customize.html#finding-the-rootdir), it says If -c is passed in the command-line, use that as configuration file, and its directory as rootdir. I don't know what will happen if rootdir is set as a non exist dir.

How to use pytest-custom_exit_code plugin

Need help!
I have a job on Gitlab ci, that runs tests and reruns failed ones. If there are no failed tests, job fails with exit code 5, that means that there are no tests for running. I found out that there is plugin "pytest-custom_exit_code", but I don't know how to correctly use it.
I need just to add command 'pytest --suppress-no-test-exit-code' to my runner.sh?
It looks like this now:
#!/bin/sh
/usr/local/bin/pytest -m test
/usr/local/bin/pytest -m --last-failed --last-failed-no-failures none test

Assumption here is that plugin is installed first using
pip install pytest-custom_exit_code
command like option pytest --suppress-no-test-exit-code should work after that.
If configuration file like .pytest.ini is used , following lines should be added in it
[pytest]
addopts = --suppress-no-test-exit-code

How to test single file under pytest

How do you test a single file in pytest? I could only find ignore options and no "test this file only" option in the docs.
Preferably this would work on the command line instead of setup.cfg, as I would like to run different file tests in the ide. The entire suite takes too long.

simply run pytest with the path to the file
something like
pytest tests/test_file.py
Use the :: syntax to run a specific test in the test file:
pytest test_mod.py::test_func
Here test_func can be a test method or a class (e.g.: pytest test_mod.py::TestClass).
For more ways and details, see "Specifying which tests to run" in the docs.

This is pretty simple:
$ pytest -v /path/to/test_file.py
The -v flag is to increase verbosity. If you want to run a specific test within that file:
$ pytest -v /path/to/test_file.py::test_name
If you want to run test which names follow a patter you can use:
$ pytest -v -k "pattern_one or pattern_two" /path/to/test_file.py
You also have the option of marking tests, so you can use the -m flag to run a subset of marked tests.
test_file.py
def test_number_one():
"""Docstring"""
assert 1 == 1
#pytest.mark.run_these_please
def test_number_two():
"""Docstring"""
assert [1] == [1]
To run test marked with run_these_please:
$ pytest -v -m run_these_please /path/to/test_file.py

This worked for me:
python -m pytest -k some_test_file.py
This works for individual test functions too:
python -m pytest -k test_about_something

Conditional Commands in tox? (tox, travis-ci, and coveralls)

tl;dr:
I'm setting up CI for a project of mine, hosted on github, using tox and travis-ci. At the end of the build, I run converalls to push the coverage reports to coveralls.io. I would like to make this command 'conditional' - for execution only when the tests are run on travis; not when they are run on my local machine. Is there a way to make this happen?
The details:
The package I'm trying to test is a python package. I'm using / planning to use the following 'infrastructure' to set up the tests :
The tests themselves are of the py.test variety.
The CI scripting, so to speak, is from tox. This lets me run the tests locally, which is rather important to me. I don't want to have to push to github every time I need a test run. I also use numpy and matplotlib in my package, so running an inane number of test cycles on travis-ci seems overly wasteful to me. As such, ditching tox and simply using .travis.yml alone is not an option.
The CI server is travis-ci
The relevant test scripts look something like this :
.travis.yml
language: python
python: 2.7
env:
- TOX_ENV=py27
install:
- pip install tox
script:
- tox -e $TOX_ENV
tox.ini
[tox]
envlist = py27
[testenv]
passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
deps =
pytest
coverage
pytest-cov
coveralls
commands =
py.test --cov={envsitepackagesdir}/mypackage --cov-report=term --basetemp={envtmpdir}
coveralls
This file lets me run the tests locally. However, due to the final coveralls call, the test fails in principle, with :
py27 runtests: commands[1] | coveralls
You have to provide either repo_token in .coveralls.yml, or launch via Travis
ERROR: InvocationError: ...coveralls'
This is an expected error. The passenv bit sends along the necessary information from travis to be able to write to coveralls, and without travis there to provide this information, the command should fail. I don't want this to push the results to coveralls.io, either. I'd like to have coveralls run only if the test is occuring on travis-ci. Is there any way in which I can have this command run conditionally, or set up a build configuration which achieves the same effect?
I've already tried moving the coveralls portion into .travis.yml, but when that is executed coveralls seems to be unable to locate the appropriate .coverage file to send over. I made various attempts in this direction, none of which resulted in a successful submission to coveralls.io except the combination listed above. The following was what I would have hoped would work, given that when I run tox locally I do end up with a .coverage file where I'd expect it - in the root folder of my source tree.
No submission to coveralls.io
language: python
python: 2.7
env:
- TOX_ENV=py27
install:
- pip install tox
- pip install python-coveralls
script:
- tox -e $TOX_ENV
after_success:
- coveralls

An alternative solution would be to prefix the coveralls command with a dash (-) to tell tox to ignore its exit code as explained in the documentation. This way even failures from coveralls will be ignored and tox will consider the test execution as successful when executed locally.
Using the example configuration above, it would be as follows:
[tox]
envlist = py27
[testenv]
passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
deps =
pytest
coverage
pytest-cov
coveralls
commands =
py.test --cov={envsitepackagesdir}/mypackage --cov-report=term --basetemp={envtmpdir}
- coveralls

I have a similar setup with Travis, tox and coveralls. My idea was to only execute coveralls if the TRAVIS environment variable is set. However, it seems this is not so easy to do as tox has trouble parsing commands with quotes and ampersands. Additionally, this confused Travis me a lot.
Eventually I wrote a simple python script run_coveralls.py:
#!/bin/env/python
import os
from subprocess import call
if __name__ == '__main__':
if 'TRAVIS' in os.environ:
rc = call('coveralls')
raise SystemExit(rc)
In tox.ini, replace your coveralls command with python {toxinidir}/run_coveralls.py.

I am using a environmental variable to run additional commands.
tox.ini
commands =
coverage run runtests.py
{env:POST_COMMAND:python --version}
.travis.yml
language: python
python:
- "3.6"
install: pip install tox-travis
script: tox
env:
- POST_COMMAND=codecov -e TOX_ENV
Now in my local setup, it print the python version. When run from Travis it runs codecov.

Alternative solution if you use a Makefile and dont want a new py file:
define COVERALL_PYSCRIPT
import os
from subprocess import call
if __name__ == '__main__':
if 'TRAVIS' in os.environ:
rc = call('coveralls')
raise SystemExit(rc)
print("Not in Travis CI, skipping coveralls")
endef
export COVERALL_PYSCRIPT
coveralls: ## runs coveralls if TRAVIS in env
#python -c "$$COVERALL_PYSCRIPT"
In tox.ini add make coveralls to commands

How to configure pycharm / intellij idea to run tox tests

Is it possible to configure pycharm / intellij idea to run tox tests? I want to test my code against different python versions in separated py environments. I was trying to configure it, but so far I only managed to configure single py.test support.

See this PyCharm issue: PY-9727
Credit goes to Andrey Vlasovskikh at PyCharm
As a workaround, you can create a Python file in your project that imports and launches Tox:
import tox
tox.cmdline()
and then run this file via your project interpreter using its context menu.
You'll get hyperlinks in the console output for stack traces, but nothing more.

I'm afraid it's not supported, PyCharm will use the configured interpreter to run the tests.
You are welcome to submit a feature request.

7 years passed and now you can run Tox inside PyCharm. If you use pytest for testing it will even show Test Result same way like with running test locally by PyCharm.
To run tests in pycharm I use config like this
[tox]
envlist = py3.{7,8},codestyle,flake8,lint
minversion = 3.7
[testenv]
usedevelop = true
deps =
pytest
pytest-cov
commands = pytest --cov=src
[testenv:codestyle]
deps = pycodestyle
commands = pycodestyle src tests
[testenv:flake8]
deps = flake8
commands = flake8 src tests
[testenv:lint]
deps = pylint
commands = pylint src tests --rcfile=.pylintrc
Here I described why it looks like this. Also, there is integration with GitHub CI to run it on every push.