title: How to force pytest to run every test (stop skipping tests not marked skip)?
body: <p>Pytest, when run from the command line, keep skipping some of my parameterized tests even though I have not told it to do so. Strangely, it does not skip the tests when run using the command palette in VSCode. </p>
  
  <p>I've tried running the tests and test files individually and tweaking the command line options, all to no avail. Presumably, there's some subtlety of configuration I'm missing. Can you help? </p>
  
  <h2>Example test</h2>
  
  <pre><code>@pytest.mark.parametrize(
      "inputs, expec",
      helpers.get_samples('inouts/kmp'),
      ids=helpers.get_ids('inouts/kmp'))
  def test_kmp(capsys, inputs, expec):
      """Sample test
      """
      with patch('kmp.sys.stdin', inputs):
          kmp.main()
      captured = capsys.readouterr()
      print(captured.err, file=sys.stderr)
      assert captured.out == expec.getvalue()
  </code></pre>
  
  <h3>Helper functions (support parametrization)</h3>
  
  <pre><code>INGLOB = '*in*'
  OUTGLOB = '*out*'
  
  def _get_globs(path):
      """Collect input/output filename pairs
      """
      if not path.endswith("/"):
          path = path + "/"
      infiles = sorted(glob.glob(path + INGLOB))
      outfiles = sorted(glob.glob(path + OUTGLOB))
      assert [i.split('.')[0]
              for i in infiles] == [o.split('.')[0] for o in outfiles]
      return zip(infiles, outfiles)
  
  
  def get_samples(path):
      """Reads sample inputs/outputs into StringIO memory buffers
      """
      files = _get_globs(path)
      inputs_outputs = []
      for infile, outfile in files:
          with open(infile, 'r') as f1:
              inputs = StringIO(f1.read())
          with open(outfile, 'r') as f2:
              outputs = StringIO(f2.read())
          inputs_outputs.append(tuple([inputs, outputs]))
      return inputs_outputs
  
  
  def get_ids(path):
      """Returns list of filenames as test ids
      """
      return [f for f, _ in _get_globs(path)]
  </code></pre>
  
  <p>Running this project in VSCode from the command palette produces: </p>
  
  <pre><code>platform darwin -- Python 3.7.2, pytest-4.1.0, py-1.7.0, pluggy-0.8.1
  rootdir: ... , inifile:
  plugins: cov-2.6.1
  collected 79 items
  
  test_1.py ........................................         [ 50%]
  test_2.py ...................................              [ 94%]
  test_3.py ....                                             [100%]
  
  generated xml file: 
  /var/folders/pn/y4jjr_t531g3x3v0s0snqzf40000gn/T/tmp-...
  ========================== 79 passed in 0.55 seconds ===========================
  </code></pre>
  
  <p>But running the same tests from the command line produces:</p>
  
  <pre><code>=============================== test session starts ===============================
  platform darwin -- Python 3.7.2, pytest-4.1.0, py-1.7.0, pluggy-0.8.1
  rootdir: ... , inifile:
  plugins: cov-2.6.1
  collected 59 items
  
  test_1.py ssss...................s.....                           [ 49%]
  test_2.py s.......................ss.s                            [ 96%]
  test_3.py s.                                                      [100%]
  
  ====================== 49 passed, 10 skipped in 0.42 seconds ======================
  </code></pre>
  
  <p>How do I get pytest to collect and run the full 76 items? I'm not using any special options in VSCode. I don't understand why pytest is skipping tests without being told to do so. </p>
  
  <p>Thanks! </p>