Pytest Testing Idioms
External
Internal
Overview
A function that starts with test
is automatically considered a test to be executed. A function that does NOT start with test
is ignored as test, so if one tries to specifically execute it, they get:
ERROR: not found: /Users/ovidiu/src/.../test_template.py::null_template_variables
A test function can be injected with a test fixture: Available fixtures: cache, capfd, capfdbinary, caplog, capsys, capsysbinary, doctest_namespace, monkeypatch, pytestconfig, record_property, record_testsuite_property, record_xml_attribute, recwarn, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory.
Tested Code is Supposed to Throw Exception
import pytest
def test_something_that_should_throw_exception():
with pytest.raises(Exception) as info:
my_method()
If the tested code raises a more specific exception, you can use that instead:
def test_something_that_should_throw_exception():
with pytest.raises(ValueError) as info:
my_method()
This tests the exception arguments. ⚠️ In this case, it is very import to place the assert
statements outside the with
block, otherwise they will be silently ignored.
def test_something_that_should_throw_exception():
with pytest.raises(ValueError) as info:
my_method()
# important: interaction with 'info' must take place outside the with block
assert info.value.args[0] == "some message"
assert "some message" in str(info.value)
Also see:
xunit-Style Setup
def setup_function(function):
"""setup any state tied to the execution of the given function.
Invoked for every test function in the module.
"""
def teardown_function(function):
"""teardown any state that was previously setup with a setup_function
call.
"""