Kotlin js plugin test conceals Karma errors

I try to test kotlin js module with new kotlin js plugin (example project). After addition to module items from kotlin.browser result of the “test” task is “BUILD SUCCESSFUL” despite a wrong assert in the test.
When this task runs with --debug option a message “… node.exe’’ finished with exit value 1 (state: FAILED)” appear in log. How do I configure the plugin or the task to see this error by default? Is possible to test the js module with the kotlin.browser contents?