title: Python : ImportError in my unittests
body: <p>This is my project structure <a href="https://i.stack.imgur.com/AewAE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/AewAE.png" alt="enter image description here"></a></p>
  
  <p>Some I've written some unit tests in <em>tommy/core/tests/test_tprotocol.py</em>, and in this file, I've this line :</p>
  
  <pre><code>from tommy.core.tprotocol import TRequest
  </code></pre>
  
  <p>But when I run unittest in the tests folder :</p>
  
  <pre><code> python -m  unittest tprotocol
  </code></pre>
  
  <p>I've an ImportError :</p>
  
  <pre><code>E
  ======================================================================
  ERROR: tprotocol (unittest.loader._FailedTest)
  ----------------------------------------------------------------------
  ImportError: Failed to import test module: tprotocol
  Traceback (most recent call last):
    File "/usr/local/Cellar/python3/3.6.0/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/loader.py", line 153, in loadTestsFromName
      module = __import__(module_name)
  ModuleNotFoundError: No module named 'tprotocol'
  
  
  ----------------------------------------------------------------------
  Ran 1 test in 0.000s
  
  FAILED (errors=1)
  </code></pre>
  
  <p>I always have this type of errors when I import a module from a subfolder...
  What is the best way for fix that ?</p>
  
  <p>But everything works if I do <code>python -m unittest tommy/core/tests/test_tprotocol.py</code></p>