title: Running unit and integration tests (residing in different directories) separately using nose
body: <p>I was wondering this already for a while now, but I was not able to figure out how to pass options to <code>nosetests</code> to run different tests which reside in different sub-directories. Example of an package directory structure:</p>
  
  <pre><code>my_package/
  |-- my_module1/
     |-- tests/
         |-- unit/
             | ... a bunch of unit tests
         |-- integration/
             |... a bunch of integration tests
  |-- my_module2/
     |-- tests/
         |-- unit/
             | ... a bunch of unit tests
         |-- integration/
             |... a bunch of integration tests
  </code></pre>
  
  <p>If I want to execute just the unit tests in all my modules (all the tests in <code>tests/unit/</code> sub-directories), how would I do that using the nosetests library?</p>