How do I use asserts in Kotlin scripts?


I understand I need to enable runtime assertions on the JVM using the -ea JVM option. But how do I do that?


You do it the same way that you do it for any JVM program. In intellij you edit your run configuration to add -ea to the command line parameters. Btw. it is also possible to enable assertions programmatically.


What does it look like from the command line?

I know this doesn’t work: kotlinc -Jea -script Example.kts


Assertions are enabled when running your program, not when compiling it. You need to pass it to the execution environment (kotlin), not the compiler (kotlinc).


OK, but kotlinc is what I use to run the script. If I use kotlin it says running Kotlin scripts is not yet supported. I guess I will have to wait then?


Kotlinc (and kotlin) is just a script that calls java. Looking at it, to pass arguments to the java command you have to prefix it with -J, but the processing just strips the first two characters (-J) and passes the rest to java. You’ll have to include the dash that Java sees. The following should work: kotlinc -J-ea -script Example.kts


Ah that works. Thank you!