is it just me or is

assert

dead? From what I see on Google it isn't even enabled by default in junit unit tests afaik

You need to run the JVM with runtime assertions enabled for assert to do anything. They are intended for use in main code rather than tests, because a test that didn’t run its assertions would be pointless and, worse, give false confidence about its results. The kotlin.test package defines assertion functions for use in tests. https://kotlinlang.org/api/latest/kotlin.test/kotlin.test/index.html#functions