How to pass arguments in pytest by command line

In your pytest test, don't use @pytest.mark.parametrize:

def test_print_name(name):    print ("Displaying name: %s" % name)

In conftest.py:

def pytest_addoption(parser):    parser.addoption("--name", action="store", default="default name")def pytest_generate_tests(metafunc):    # This is called for every test. Only get/set command line arguments    # if the argument is specified in the list of test "fixturenames".    option_value = metafunc.config.option.name    if 'name' in metafunc.fixturenames and option_value is not None:        metafunc.parametrize("name", [option_value])

Then you can run from the command line with a command line argument:

pytest -s tests/my_test_module.py --name abc

Use the pytest_addoption hook function in conftest.py to define a new option.
Then use pytestconfig fixture in a fixture of your own to grab the name.
You can also use pytestconfig from a test to avoid having to write your own fixture, but I think having the option have it's own name is a bit cleaner.

# conftest.pydef pytest_addoption(parser):    parser.addoption("--name", action="store", default="default name")

# test_param.py import pytest@pytest.fixture()def name(pytestconfig):    return pytestconfig.getoption("name")def test_print_name(name):        print(f"\ncommand line param (name): {name}")def test_print_name_2(pytestconfig):    print(f"test_print_name_2(name): {pytestconfig.getoption('name')}")

# in action$ pytest -q -s --name Brian test_param.pytest_print_name(name): Brian.test_print_name_2(name): Brian.

I stumbled here looking for how to pass an argument, but I wanted to avoid parameterizing the test. The answers above do perfectly well address the exact question of parameterizing a test from the command line, but I would like to offer an alternative way to pass a command line argument to particular tests. The method below uses a fixture and skips the test if the fixture is specified but the argument is not:

test.py:

def test_name(name):    assert name == 'almond'

conftest.py:

import pytestdef pytest_addoption(parser):    parser.addoption("--name", action="store")@pytest.fixture(scope='session')def name(request):    name_value = request.config.option.name    if name_value is None:        pytest.skip()    return name_value

Examples:

$ py.test tests/test.py=========================== test session starts ============================platform linux -- Python 3.7.1, pytest-4.0.0, py-1.7.0, pluggy-0.8.0rootdir: /home/ipetrik/dev/pytest_test, inifile:collected 1 itemtests/test.py s                                                      [100%]======================== 1 skipped in 0.06 seconds =========================

$ py.test tests/test.py --name notalmond=========================== test session starts ============================platform linux -- Python 3.7.1, pytest-4.0.0, py-1.7.0, pluggy-0.8.0rootdir: /home/ipetrik/dev/pytest_test, inifile:collected 1 itemtests/test.py F                                                      [100%]================================= FAILURES =================================________________________________ test_name _________________________________name = 'notalmond'    def test_name(name):>       assert name == 'almond'E       AssertionError: assert 'notalmond' == 'almond'E         - notalmondE         ? ---E         + almondtests/test.py:5: AssertionError========================= 1 failed in 0.28 seconds =========================

$ py.test tests/test.py --name almond=========================== test session starts ============================platform linux -- Python 3.7.1, pytest-4.0.0, py-1.7.0, pluggy-0.8.0rootdir: /home/ipetrik/dev/pytest_test, inifile:collected 1 itemtests/test.py .                                                      [100%]========================= 1 passed in 0.03 seconds =========================