Pytest Options: Best Practices and Examples
Last updated:- Show stdout output
- Add current directory to path
- Suppress warnings
- Suppress deprecationwarnings
- Run single test
- Mark.parametrize example
- Enable doctest
- Assert exception is raised
Show stdout output
pass --capture=tee-sys to the command:
$ pytest --capture=tee-sys
Add current directory to path
Call pytest as a module: python -m pytest (instead of just pytest)
Suppress warnings
Add to pytest.ini:
[pytest]
addopts = -p no:warnings
Suppress deprecationwarnings
Add to pytest.ini:
[pytest]
filterwarnings =
ignore:.+:DeprecationWarning
Run single test
Use -k 'test_name' when running pytest.
This will only run tests whose name match the string "test_name"
Example: To run only test test_foo():
$ pytest path/to/tests.py -k 'test_foo'
Mark.parametrize example
To run multiple tests where only the input/outputs are different, use pytest.mark.parametrize:
Example: Run the same test 3 times, for different pairs of input/outputs:
import pytest
# run 3 tests at once
@pytest.mark.parametrize(
'num1, num2, result', # define the parameters
[[2, 2, 4], # list of lists with the values
[1, 1, 2],
[2, 3, 5]])
def test_add(num1, num2, result): # parameters must match the names above
assert num1 + num2 == result
Output (3 tests were run):
$ pytest tests.py
=================== test session starts =================
collected 3 items
tests.py ... [100%]
Enable doctest
See how to create doctests here: Python Docstrings Examples: Doctest
Add this pytest.ini to have doctests also run when you run pytest:
[pytest]
addopts = --doctest-modules
Assert exception is raised
Use with pytest.raises(ValueError): as a context manager:
# inside my_test.py
def test_raises_index_error():
with pytest.raises(IndexError):
arr = [1,2,3]
arr[1]
Run using $ pytext at the root:
$ pytest
============================= test session starts ==============================
platform linux -- Python 3.8.10, pytest-7.1.2, pluggy-1.0.0
plugins: anyio-3.3.4
collected 1 item
tests/my_test.py . [100%]
============================== 1 passed in 0.02s ===============================