title: How to mark specific combinations of parametrized pytest arguments?
body: <p>According to the <a href="https://docs.pytest.org/en/latest/parametrize.html#pytest-mark-parametrize-parametrizing-test-functions" rel="noreferrer">pytest documentation</a>, I can generate combinations of multiple parametrized arguments as follows:</p>
  
  <pre><code>@pytest.mark.parametrize("x", [0, 1])
  @pytest.mark.parametrize("y", [2, 3])
  def test_foo(x, y):
      pass
  </code></pre>
  
  <p>I can also apply marks to individual parameters as such:</p>
  
  <pre><code>@pytest.mark.parametrize("test_input,expected", [
  ("3+5", 8),
  ("2+4", 6),
  pytest.param("6*9", 42,
               marks=pytest.mark.xfail),
  ])
  def test_eval(test_input, expected):
      assert eval(test_input) == expected
  </code></pre>
  
  <p>Is there a reasonable way to combine the two methodologies and apply a mark to a particular combination of parameters? For instance, can I apply a <code>pytest.mark.xfail</code> ONLY to the <code>test_foo</code> instance that gets generated with <code>x==0</code> and <code>y==2</code>?</p>