IntelliJ IDEA – enable Java 1.4 assertions for Junit Run/Debug configurations

I recently ran into a test discrepancy where my test was failing when running it via the maven surefire plugin, yet it passed when I ran it through IntelliJ’s JUnit runner.

After spending a ridiculous amount of time on this issue, I was finally able to pinpoint the discrepancy to the Java 1.4 introduced “assert” statement and the differences in the default behavior of the maven surefire plugin and the IntelliJ JUnit runner.  The maven surefire plugin (v 2.7.2) enables JVM assertions by default.  IntelliJ’s JUnit runner does not (v 9.0.4).  My test in question happened to be failing due to a failing assert in an included xml parsing library.

To change the default behavior of the JUnit runner, edit the Run/Debug configurations, select Edit Defaults, select JUnit, and add “-ea” or “-enableassertions” to the VM parameters.