Adding Kotlin to your code base via a test-first approach can be a safe way of integrating and experimenting with the language. By starting with tests, development teams can incorporate the language into their projects with minimal impact on their production artifacts. This can be a good way to convince reluctant management to try Kotlin.
Writing test code in multiple languages can also help improve the interop experience between existing Java code and Kotlin. It demonstrates how easily the two languages can be used together, and it can illustrate areas where Kotlin features or APIs are more cumbersome than Java.
Writing tests in Kotlin can also be highly efficient and expressive, if you use the available testing libraries that make use of Kotlin DSLs. All of these add up to an enjoyable testing experience with Kotlin and a viable path forward toward adding Kotlin to your...
