title: I get a "database does not exist error" when running unit tests
body: <p>Every time I run the command:</p>
  
  <pre><code>rake test test/models/post_test.rb test_the_truth
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre class="lang-none prettyprint-override"><code>`initialize': FATAL:  database "knome_test" does not exist (PG::Error).
  </code></pre>
  
  <p>Can someone explain and help me to debug it? </p>