From raoul at snyman.info  Wed Jun 15 13:56:03 2022
From: raoul at snyman.info (Raoul Snyman)
Date: Wed, 15 Jun 2022 17:56:03 +0000
Subject: [openlp-dev] Parametrize Your Tests
Message-ID: <168a3e3f083b8dabc403dfc418cab20b@snyman.info>

Hey everyone,

Ever found yourself writing a for-loop in a test, and wondering if 
there's a better way to do it? Kinda like this?

def test_media_length(media_env):
      """
      Check the duration of a few different files via MediaInfo
      """
     for test_data in TEST_MEDIA:
         # GIVEN: a media file
         full_path = str(TEST_PATH / test_data[0])

         # WHEN the media data is retrieved
         results = media_env.media_controller.media_length(full_path)

         # THEN you can determine the run time
         assert results == test_data[1], 'The correct duration is 
returned for ' + test_data[0]


Yes, there is a better way! It's called "parametrization". Here's how 
you fix the test above:


@pytest.mark.parametrize('file_name,media_length', TEST_MEDIA)
def test_media_length(file_name, media_length, media_env):
      """
      Check the duration of a few different files via MediaInfo
      """
     # GIVEN: a media file
     full_path = TEST_PATH / file_name

     # WHEN the media data is retrieved
     results = media_env.media_controller.media_length(full_path)

     # THEN you can determine the run time
     assert results == media_length, f'The correct duration for 
{file_name} should be {media_length}, was {results}'


Now pytest will take care of running the test multiple times using the 
parameters you supplied.


-- 
Raoul Snyman