title: Configuring pytest rootdir?
body: <p>I've got a project with the following directory structure:</p>
  
  <pre><code>.
  ..
  core/start.py
  tests/test_curve.py
  pytest.ini
  </code></pre>
  
  <p>The contents of pytest.ini are:</p>
  
  <pre><code>[pytest]
  testpaths = tests
  </code></pre>
  
  <p>The contents of <code>test_curve.py</code> are:</p>
  
  <pre><code>import core.start
  
  def test_curve():
      assert some_valid_stuff
  </code></pre>
  
  <p>When I run pytest in the project root folder, I get:</p>
  
  <pre><code>import core.start
  ImportError: No module named 'core'
  </code></pre>
  
  <p>What am I doing wrong?</p>