I'm writing selenium tests, with a set of classes, each class containing several tests. Each class currently opens and then closes Firefox, which has two consequences:

• super slow, opening firefox takes longer than running the test in a class...
• crashes, because after firefox has been closed, trying to reopen it really quickly, from selenium, results in an 'Error 54'

I could solve the error 54, probably, by adding a sleep, but it would still be super slow.

So, what I'd like to do is reuse the same Firefox instances across all test classes. Which means I need to run a method before all test classes, and another method after all test classes. So, 'setup_class' and 'teardown_class' are not sufficient.

5

4 Answers

Using session fixture as suggested by hpk42 is great solution for many cases, but fixture will run only after all tests are collected.

Here are two more solutions:

conftest hooks

Write a pytest_configure or pytest_sessionstart hook in your conftest.py file:

# content of conftest.py
def pytest_configure(config): """ Allows plugins and conftest files to perform initial configuration. This hook is called for every plugin and initial conftest file after command line options have been parsed. """
def pytest_sessionstart(session): """ Called after the Session object has been created and before performing collection and entering the run test loop. """
def pytest_sessionfinish(session, exitstatus): """ Called after whole test run finished, right before returning the exit status to the system. """
def pytest_unconfigure(config): """ called before test process is exited. """

pytest plugin

Create a pytest plugin with pytest_configure and pytest_unconfigure hooks.
Enable your plugin in conftest.py:

# content of conftest.py
pytest_plugins = [ 'plugins.example_plugin',
]
# content of plugins/example_plugin.py
def pytest_configure(config): pass
def pytest_unconfigure(config): pass

3

You might want to use a session-scoped "autouse" fixture:

# content of conftest.py or a tests file (e.g. in your tests or root directory)
@pytest.fixture(scope="session", autouse=True)
def do_something(request): # prepare something ahead of all tests request.addfinalizer(finalizer_function)

This will run ahead of all tests. The finalizer will be called after the last test finished.

3

Starting from version 2.10 there is a cleaner way to tear down the fixture as well as defining its scope. So you may use this syntax:

@pytest.fixture(scope="module", autouse=True)
def my_fixture(): print ('INITIALIZATION') yield param print ('TEAR DOWN')

The autouse parameter:From documentation:

Here is how autouse fixtures work in other scopes:

• autouse fixtures obey the scope= keyword-argument: if an autouse fixture has scope='session' it will only be run once, no matter where it is defined. scope='class' means it will be run once per class, etc.

• if an autouse fixture is defined in a test module, all its test functions automatically use it.

• if an autouse fixture is defined in a conftest.py file then all tests in all test modules below its directory will invoke the fixture.

  ...

The "request" parameter:Note that the "request" parameter is not necessary for your purpose although you might want to use it for other purposes. From documentation:

"Fixture function can accept the request object to introspect the “requesting” test function, class or module context.."

0

Try to use pytest_sessionstart(session) in conftest.py

Example:

# project/tests/conftest.py
def pytest_sessionstart(session): print('BEFORE')

# project/tests/tests_example/test_sessionstart.py
import pytest
@pytest.fixture(scope='module', autouse=True)
def fixture(): print('FIXTURE')
def test_sessonstart(): print('TEST')

Log:

BEFORE
============================================================================ test session starts =============================================================================
platform darwin -- Python 3.7.0, pytest-5.4.1, py-1.8.1, pluggy-0.13.1 -- /Library/Frameworks/
cachedir: .pytest_cache
rootdir: /Users/user/Documents/test, inifile: pytest.ini
plugins: allure-pytest-2.8.12, env-0.6.2
collected 1 item
tests/6.1/test_sessionstart.py::test_sessonstart FIXTURE
TEST
PASSED

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