I am using JUnit to write some higher level tests for legacy code that does not have unit tests.

Much of this code "swallows" a variety of unchecked exceptions like NullPointerExceptions (e.g., by just printing stack trace and returning null). Therefore the unit test can pass even through there is a cascade of disasters at various points in the lower level code.

Is there any way to have a test fail on the first unchecked exception even if they are swallowed?

The only alternative I can think of is to write a custom JUnit wrapper that redirects System.err and then analyzes the output for exceptions.