title: Ruby on Rails: Switch from test_unit to rspec
body: <p>I'm going through a tutorial that has suggested using <code>rspec</code>, but I have already gone through a lot of default rails installation.  I really don't want to have to redo the installation at all.  Anyway, when I run</p>
  
  <pre><code>$ rails g integration_test named
  </code></pre>
  
  <p>I get</p>
  
  <pre><code>  invoke  test_unit
    create    test/integration/named_test.rb
  </code></pre>
  
  <p>When I run <code>bundle</code>, various <code>rspec</code> gems are listed, but <code>test_unit</code> is not.  The tutorial seems to have rails invoke <code>rspec</code> instead of <code>test_unit</code> without doing anything additional. How do I get rails to use <code>rspec</code> with the integration test generator command?</p>