I use karma with jasmine. The output of not equal objects in jasmine could be very confusing, because it could be a very long line with only little difference. I wrote an plugin that provides a diff mechanism for that with com.intellij.diff.DiffManager. Small plugin that make life really more easy.
Unfortunately, my filter is neglected because the KarmeExecutionSession sets usePredefinedMessageFilter to false.
Is it possible to set true? Please compare Pull Request https://github.com/JetBrains/intellij-plugins/pull/366
That would allow a whole bunch of additional plugins that enhancing the output of test results.