How to solve issue with fixture not found in pytest?

  fixtures, pytest, python, testing

I am trying to use the pytester fixture, to create some files in the test directory, but I get the following error:

  def test_something(pytester):
E       fixture 'pytester' not found
>       available fixtures: _configure_application, _monkeypatch_response_class, _push_request_context, accept_any, accept_json, accept_jsonp, accept_mimetype, cache, capfd, capfdbinary, caplog, capsys, capsysbinary, class_mocker, client, client_class, config, cov, doctest_namespace, live_server, mock_sparql_endpoint, mocker, module_mocker, monkeypatch, no_cover, package_mocker, pytestconfig, quotation_access_db_columns, quotation_access_db_path, record_property, record_testsuite_property, record_xml_attribute, recwarn, request_ctx, session_mocker, sparql_query1, tmp_path, tmp_path_factory, tmpdir, tmpdir_factory
>       use 'pytest --fixtures [testpath]' for help on them.

The code I am trying to run, to create some python files in below, taken from the pytester documentation:

def test_something(pytester):
    # Initial file is created
    # To create multiple files, pass kwargs accordingly.
    # At this point, both '' & '' exist in the test directory.

How can I use the pytester fixture to create some files in the test directory?
The link for the pytester documentation:

Source: Python Questions