title: PyCharm: Unable to run tests 'All in folder'
body: <p>I am trying to run my whole test suite in PyCharm.   All of the test files are in a single folder.  I can run the files individually, but when I create a run configuration with 'All in folder' PyCharm is unable to find any tests.</p>
  
  <p>The messages logged are:</p>
  
  <pre><code>C:\Python36\python.exe "C:\Program Files (x86)\JetBrains\PyCharm Community Edition 2016.3.2\helpers\pycharm\utrunner.py" C:\Users\John\PycharmProjects\Kojak\tests\_args_separator_.*\.py$ true
  Testing started at 14:56 ...
  
  Process finished with exit code 0
  Empty test suite. 
  </code></pre>
  
  <p>I noticed the <code>_args_separator_</code> in the path, so what is that all about?</p>
  
  <p>I am running under Windows 7 with PyCharm 2016.3 and Python 2.6</p>