This GitHub repository is meant for collecting pytest example code to introduce colleagues to pytest.
Pytest is a python based testing framework, which is used to write and execute test code. You can write code to test anything like database , API. But in the industry pytest is mainly used to write tests for APIs.
- Pytest can run multiple tests in parallel, which reduces the execution time of the test suite.
- Pytest has its own way to detect the test file and test functions automatically, if not mentioned explicitly.
- Pytest allows us to skip a subset of the tests during execution.
- Pytest allows us to run a subset of the entire test suite.
- Pytest is free and open source.
- Because of its simple syntax, pytest is very easy to start with
- Pytest can be used with most existing test suites, like nosetest, python unittest, doctest.
Get sources from GitHub:
$ git clone https://github.com/neumannd/pytest_fun.git
$ cd pytest_fun
You can use a conda environment with Python 3.8:
$ conda create -n pytest_fun python=3.8 pytest numpy
$ conda activate pytest_fun
Run the installation:
$ python setup.py develop
Run all tests with pytest:
$ pytest
This will run all the filenames starting with test_ and the filenames ending with _test in that folder and subfolders under that folder.
To run tests only from a specific file, we can use:
$ pytest tests\test_simple.py
$ pytest -x # stop after first failure
$ pytest --maxfail=2 # stop after two failures
$ pytest -v # verbose
$ pytest -m use_fixtures # run only specific tests marked with the tag
# `use_fixtures` (details below in "pytest markers")
see also: https://gist.github.com/kwmiebach/3fd49612ef7a52b5ce3a
Add pytest-html to conda environment:
$ conda install pytest-html
Run pytest and create html output:
$ pytest --html=report.html
If during implementing your tests you realize that you want to use a fixture function from multiple test files you can move it to a conftest.py file. You don’t need to import the fixture you want to use in a test, it automatically gets discovered by pytest. The discovery of fixture functions starts at test classes, then test modules, then conftest.py files and finally builtin and third party plugins.
We can use pytest markers to select only a subset of tests to run. This is useful if some tests only work in specific environments (with database access; unter certain operation systems). Markers are defined in the pytest.ini file. Then, functions can be individually marked with them.
Example for definition of markers in pytest.ini:
markers =
use_fixtures: tests are performed in which pytest.fixtures are used
use_parameterize: tests are performed in which pytest.mark.parameterize is used
skipped_and_xfailing_tests: test that are marked to be skipped or marked to fail (`xfail`)
Example for marking a functions with a marker:
@pytest.mark.use_fixtures
def test_write_int_to_file():
# define a temporary directory
tmpdir = Path('/tmp')
file_path = tmpdir / 'my_file.txt'
write_int_to_file(5, file_path)
assert file_path.read_text() == '5'To performed only tests marked by marked use_fixtures (example) do:
pytest -m use_fixturesTo perform all tests except those marked by use_fixtures (example) do:
pytest -m "not use_fixtures"- url: https://github.com/ioos/compliance-checker
- tests directory: compliance_checker/tests
- one testing file per module
- pytest decorators: does only use marks
- see
pytest.iniin root directory for usage of some possible control parameters
Sometimes you have a database or an external service which is not available for your test environment. In theses cases you can use mock modules to fake the responses of the database/service to return an expected value. The database/service don't need to be available to run the test code.
- https://docs.pytest.org/en/latest/monkeypatch.html
- https://docs.python.org/dev/library/unittest.mock.html
- @am-kaiser
- @MacPingu
- @neumannd