• What is the fixture?
• Built-in fixtures
• How to create a fixture?
• How to use the fixture?
• Using Fixtures for Test Data
• Using Multiple Fixtures
• Fixtures Scope
• Renaming fixtures
• Parametrizing Fixtures
• Use fixture as a parameter for another class
• Fixtures is used in mark.parametrize and which get the parameters, indirect=True
• Create fixture inside a class
• Fixture to a class is applied to each test

What is the fixture?

• Such as setUp() and teardown() methods, “getting ready for” and “cleaning up after”
• the code above the yield as “setup” and the code after yield as “teardown.”
• Fixtures are used to feed some data to the tests such as database connections, URLs to test and some sort of input data.
• if you wanted a test to use a fixture, you put it in the parameter list. But for classes that’s better to use @pytest.mark.usefixtures('fixture1', 'fixture2').
• test using a fixture due to usefixtures cannot use the fixture’s return value
• pytest --setup-show test_add.py -k valid_id ← to see what setup and teardown methods were being used
• F’s and S’s for function and session scope
• autouse=True as fixture argument, it runs all of the time for all functions
• @pytest.fixture(autouse=True, scope='class/module/session', params=[], ids=[])

Built-in fixtures

• tmpdir, request, pytestconfig …

How to create a fixture?

• SetUp and TearDown function
Copy

@pytest.fixture(autouse=True)
def initialized_tasks_db(tmpdir):
    """Connect to db before testing, disconnect after."""
    # Setup : start db
		tasks.start_tasks_db(str(tmpdir), 'tiny') 

		yield # this is where the testing happens

    # Teardown : stop db
    tasks.stop_tasks_db()

Copy

@pytest.fixture()
def my_fixture_func():
	print('Hello')
	yield 
	print('World')

• Data fixture → passing to argument list
Copy

import pytest
@pytest.fixture() 
def some_data():
    """Return answer to ultimate question."""
		return 42

def test_some_data(some_data):
	"""Use fixture return value in a test.""" 
	assert some_data == 42

How to use the fixture?

• To use any built-in or user defined fixture we need to pass the fixture name as the argument to function
• pytest will look in the module of the test for a fixture of that name. It will also look in conftest.py files if it doesn’t find it in this file.
• in conftest.py fixtures will be visible to all modules

Using Fixtures for Test Data

Using Multiple Fixtures

Fixtures Scope

Scope controls how often a fixture gets set up and torn down.

• Can have values: function, class, module, or session
• The default is function

@pytest.fixture(autouse=True, scope='session') 
def footer_session_scope():
   """Report the time at the end of a session."""
	yield
	now = time.time()
	print('--')
	print('finished : {}'.format(time.strftime('%d %b %X', time.localtime(now)))) 
	print('-----------------')

Renaming fixtures

import pytest

@pytest.fixture(name='lue')
def ultimate_answer_to_life_the_universe_and_everything():
    """Return ultimate answer."""
		return 42

def test_everything(lue): 
"""Use the shorter name.""" 
		assert lue == 42

Parametrizing Fixtures

better than @pytest.mark.parametrize('task', tasks_to_try)

• With ids → @pytest.fixture(params=tasks_to_try, ids=task_ids)
• request.keywords

Use fixture as a parameter for another class

@pytest.fixture
def dir1_fixture():
    return '/dir1'

@pytest.fixture
def dir2_fixture():
    return '/dir2'

@pytest.fixture(params=['dir1_fixture', 'dir2_fixture'])
def dirname(request):
    return request.getfixturevalue(request.param)

@pytest.fixture(params=["123344", "45678"], ids=range(2))
def test_data(request):
    return {"a": request.param}

def test_me_too(test_data):
    print(test_data)

Fixtures is used in mark.parametrize and which get the parameters, indirect=True

import pytest

@pytest.fixture
def fixture_name(request):
    return request.param

@pytest.mark.parametrize('fixture_name', ['foo', 'bar'], indirect=True)
def test_indirect(fixture_name):
    assert fixture_name == 'baz'


# indirect=True ensures you still execute the fixture body when you use parametrize on a test.
# similar to @pytest.fixture(params=[..]_

Create fixture inside a class

or even

Fixture to a class is applied to each test

@pytest.fixture
def a():
    print("A")


@pytest.fixture
def b():
    print("B")


@pytest.mark.usefixtures('b')
@pytest.mark.usefixtures('a')
class TestMe:
    def test_me(self):
        print("ME")

    def test_him(self):
        print("HIM")