title: How to get stack trace from a Test::Unit::TestCase
body: <p>I am testing some Ruby code and have a failing Test::Unit::TestCase. Unfortunately, the failure report only gives me the top error, not a full stack trace. Specifically, it says:</p>
  
  <pre><code> 1) Failure:
  test_tp_make(TestScripts::TestTpMake) [test/test_scripts.rb:73]:
  Exception raised:
  &lt;#&lt;NoMethodError: undefined method `[]' for nil:NilClass&gt;&gt;.
  </code></pre>
  
  <p>The line number referenced (73) is the start of an assert_nothing_raised code block in my test case, which in turn starts another code block, which in turn calls in to a large library.</p>
  
  <p>I have tried running the test with the --verbose flag, unfortunately this does not change the exception output. I tried consulting the Test::Unit documentation, but it does not seem to enumerate the available options (for example, there's nothing useful <a href="http://ruby-doc.org/stdlib-1.9.3/libdoc/test/unit/rdoc/Test/Unit/Options.html">here</a>). Searching the web and StackOverflow surfaced some answers on how to enable stack tracing in Rails, but this is non-Rails ruby code.</p>
  
  <p>I could extract the failing code from the test and run it outside of Test::Unit, enabling me to see all the output. But it will be a pain to do this every time I have a failing test.</p>
  
  <p>Does anyone know how to get Test::Unit to give me a full stack trace?</p>