How can I import helper functions in test files without creating packages in the
I’d like to create a test helper function that I can import in several tests. Say, something like this:
# In common_file.py def assert_a_general_property_between(x, y): # test a specific relationship between x and y assert ... # In test/my_test.py def test_something_with(x): some_value = some_function_of_(x) assert_a_general_property_between(x, some_value)
Using Python 3.5, with py.test 2.8.2
I’m currently doing this via importing a module inside my project’s
test directory (which is now a package), but I’d like to do it with some other mechanism if possible (so that my
test directory doesn’t have packages but just tests, and the tests can be run on an installed version of the package, as is recommended here in the py.test documentation on good practices).
my option is to create an extra dir in
tests dir and add it to pythonpath in the conftest so.
tests/ helpers/ utils.py ... conftest.py setup.cfg
import sys import os sys.path.append(os.path.join(os.path.dirname(__file__), 'helpers'))
this module will be available with `import utils’, only be careful to name clashing.
While searching for a solution for this problem I came across this SO question and ended up adopting the same approach. Creating a helpers package, munging
sys.path to make it importable and then just importing it…
This did not seem the best approach, so, I created pytest-helpers-namespace. This plugin allows you to register helper functions on your
import pytest pytest_plugins = ['helpers_namespace'] @pytest.helpers.register def my_custom_assert_helper(blah): assert blah # One can even specify a custom name for the helper @pytest.helpers.register(name='assertme') def my_custom_assert_helper_2(blah): assert blah # And even namespace helpers @pytest.helpers.asserts.register(name='me') def my_custom_assert_helper_3(blah): assert blah
And then, within a test case function body just use it like
def test_this(): assert pytest.helpers.my_custom_assert_helper(blah) def test_this_2(): assert pytest.helpers.assertme(blah) def test_this_3(): assert pytest.helpers.asserts.me(blah)
Its pretty simple and the documentation pretty small. Take a look and tell me if it addresses your problem too.
You could define a helper class in conftest.py, then create a fixture that returns that class (or an instance of it, depending on what you need).
import pytest class Helpers: @staticmethod def help_me(): return "no" @pytest.fixture def helpers(): return Helpers
Then in your tests, you can use the fixture:
def test_with_help(helpers): helpers.help_me()
Create a helpers package in tests folder:
# make sure no __init__.py in here!
the helpers will be available with
As another option, this directory structure worked for me:
mypkg/ ... test_helpers/ __init__.py utils.py ... tests/ my_test.py ...
And then in
my_test.py import the utilities using:
from test_helpers import utils