title: ModuleNotFoundError seen when running test
body: <p>I have a project directory as below:</p>
  <pre><code>bin/
  bin/module1/module1.py
  bin/module1/settings.py 
  bin/module1/helpers.py  --&gt; This module does not have reference to bin/module1/settings.py
  bin/module2/module2.py
  bin/module2/settings.py
  bin/module2/helpers.py --&gt; This module has reference to bin/module2/settings.py
  bin/tests/test_module1.py --&gt; This test imports helpers from bin/module1/helpers.py
  bin/tests/test_module2.py --&gt; This test imports helpers from bin/module2/helpers.py
  bin/tox.ini
  bin/conftest.py
  bin/setup.py
  </code></pre>
  <p>setup.py has below contents:</p>
  <pre><code>from setuptools import setup, find_packages
  
  setup(
      name='my_project',
      version='0.0.1',
      description='Implement my_project',
      long_description='Implement my_project',
      author='my_name',
      author_email='a.my_name@my_domain.com',
      packages=find_packages(exclude=['tests*'])
  )
  </code></pre>
  <p>I am using pytest.</p>
  <p>When I run <code>test_module1.py</code>, which refers <code>bin/module1/helpers.py</code> using pytest markers and <code>bin/module1/helpers.py</code> does not have import to  <code>bin/module1/settings.py</code>. The test run perfectly fine.</p>
  <p>But, when I run <code>bin/tests/test_module2.py</code> using pytest markers, and <code>bin/module2/helpers.py</code> has import to <code>bin/module2/settings.py</code>, when this test runs I see the <code>ModuleNotFoundError: No module named 'settings' error</code></p>
  <pre><code>    import settings as settings
  E   ModuleNotFoundError: No module named 'settings'
  </code></pre>