# content of conftest.py import pytest def pytest_addoption(parser): parser.addoption( "--all", action="store_true", help="Run all back-ends" ) def pytest_generate_tests(metafunc): if "backend" in metafunc.fixturenames: if metafunc.config.getoption("all"): backends = ['hdf5', 'text'] else: backends = ['text'] metafunc.parametrize("backend", backends)