title: How to use override parameters of a fixture in Pytest?
body: <p>Let's say I have a parameterized fixture like this:</p>
  
  <pre><code>@pytest.fixture(params=[1, 2, 800]):
  def resource(request):
      return Resource(capacity=request.param)
  </code></pre>
  
  <p>When I use the fixture as parameter in a test function, Pytest runs the test with all three versions:</p>
  
  <pre><code>def test_resource(resource):  # Runs for capacities 1, 2, and 800.
      assert resource.is_okay()
  </code></pre>
  
  <p>However, for some tests I want to change the parameters for which the fixture gets built:</p>
  
  <pre><code>def test_worker(resource, worker):  # Please run this for capacities 1 and 5.
      worker.use(resource)
      assert worker.is_okay()
  </code></pre>
  
  <p>How can I specify to only receive certain versions of the specified fixture?</p>