Cause unknown. When run by itself, it doesn't always fail. It fails pretty consistently when run as part of the whole suite, or when run repeatedly.
It seems like all the test methods pass, but the test still fails.
[junit] Testsuite: edu.rice.cs.drjava.model.print.DrJavaBookTest
[junit] Tests run: 3, Failures: 0, Errors: 0, Time elapsed: 0.406 sec
[junit]
[junit] Testcase: testGetNumberOfPages took 0.359 sec
[junit] Testcase: testGetPageFormat took 0 sec
[junit] Testcase: testGetPrintable took 0.047 sec
[junit] Test edu.rice.cs.drjava.model.print.DrJavaBookTest FAILED
Fails both with the original JUnit and with ConcJUnit.