title: Conditionally ignoring tests in JUnit 4
body: <p>OK, so the <code>@Ignore</code> annotation is good for marking that a test case shouldn't be run.</p>
  
  <p>However, sometimes I want to ignore a test based on runtime information.  An example might be if I have a concurrency test that needs to be run on a machine with a certain number of cores.  If this test were run on a uniprocessor machine, I don't think it would be correct to just pass the test (since it hasn't been run), and it certainly wouldn't be right to fail the test and break the build.</p>
  
  <p>So I want to be able to ignore tests at runtime, as this seems like the right outcome (since the test framework will allow the build to pass but record that the tests weren't run).  I'm fairly sure that the annotation won't give me this flexibility, and suspect that I'll need to manually create the test suite for the class in question.  However, the documentation doesn't mention anything about this and looking through the <a href="http://junit.org/apidocs/junit/framework/TestSuite.html" rel="noreferrer">API</a> it's also not clear how this would be done programmatically (i.e. how do I programatically create an instance of <code>Test</code> or similar that is equivalent to that created by the <code>@Ignore</code> annotation?).</p>
  
  <p>If anyone has done something similar in the past, or has a bright idea of how else I could go about this, I'd be happy to hear about it.</p>