I wanted to write this short post to highlight the assertFailsWith function available to Kotlin that makes testing exceptions a bit easier. Testing exceptions isn’t something fancy or new to JVM languages (from now on, I will use Java for comparisons), but Kotlin comes with the nice extra benefit of providing this functionality as part of its standard library. Comparing this to Java, you are likely to bring AssertJ into the mix to achieve similar results.
The main purpose of this post is to make you aware of the assertFailsWith function. I personally did not know it existed for a while and defaulted to depending on AssertJ. Not that I have anything against AssertJ that is. There are many other features that the library provides, but for this specific instance, it might be possible to remove it (assuming you are not using it for anything else that is).