FAQ:

• Why should I ever have to kill a "Current Test"?
  Well, in general, you shouldn't have to.  However, many things may cause a lab to freeze.  For example, your student may have inadvertently written an infinite loop.  Certain exceptions may cause problems.  Who knows?  What's important is: the lab just isn't working.  Thus, you'll have to manually end the test.  The results file will show this by reporting: "ERROR: Cancelled".  You may choose to take a closer look at labs that have this problem.

• How do I write a JUnit test file for a class where each student has the freedom to design the class as she wishes?
  No problem. Just have the requirement that the class have a toString() method. You can require the exact makeup of the returned String (usually made up of all of the instance data, for example). You'll now have a way of testing the object's current state (i.e., by comparing toString() to your known String answer).

• Reading/Writing files
  No problem. Just make sure to use the entire path to your file.
  e.g., IO.openFile("z:\\directory1\\dataFiles\\data.txt")