old_contents: import pytest
  
  
  @pytest.fixture(scope='session')
  def base_url(base_url, request):
      return base_url or 'https://developer.allizom.org'
  
  
new_contents: import pytest
  
  VIEWPORT = {
      'large': {'width': 1201, 'height': 1024}, # also nav-break-ends
      'desktop': {'width': 1025, 'height': 1024},
      'tablet': {'width': 851, 'height': 1024}, # also nav-block-ends
      'mobile': {'width': 481, 'height': 1024},
      'small': {'width': 320, 'height': 480}}
  
  @pytest.fixture(scope='session')
  def base_url(base_url, request):
      return base_url or 'https://developer.allizom.org'
  
  @pytest.fixture
  def selenium(request, selenium):
      viewport = VIEWPORT['large']
      if request.keywords.get('viewport') is not None:
          viewport = VIEWPORT[request.keywords.get('viewport').args[0]]
      selenium.set_window_size(viewport['width'], viewport['height'])
      return selenium
  
subject: Add viewport sizes fixture to tests.