A modern programming language that makes developers happier.

kotlinlang

I do use `when` in my main code. This is just in a test class. I am just surprised the compiler was understanding that `result` must be a `Post` just because `post` is from a cast. Especially is it is possible for my function to return a `PostGeneration.Error` _or a_ `<http://PostGeneration.Post|PostGeneration.Post>`. I'm going to write a test case which should return a `PostGeneration.Error` and see what happens...

if `result` is `Post` then everything will work as expected
if `result` is `Error` then class cast exception will be thrown and no statements after cast will be executed
so compiler assumption is safe

I think in 1.3 version (because of contracts) compiler will assume that `result` is `Post` just after `assertTrue(isPost)` statement.

This is all rather cool. I'm going to litter my code with sealed classes now!