A modern programming language that makes developers happier.

kotlinlang

The idea is do have a type of assertion composition, since as something not null, I need to assert more to assure that the result is as expected. Whereas `whenNotNull` is not an assertion, and is the same as `result?.let  { }` and this will not lead to any runtime failure (nor is it really asserting anything, if null, which I feel is not such good testing practice... but that's my opinion). 

As mentioned before, `result!! should { }` is not an assertion, and will lead to a runtime failure. So `shouldNotBeNull { }` really makes the assertion, and allows to continue asserting on a non-null value.

I admit that if contracts would be an option, there would likely not be a need for the lambda though...

Also `shouldBeInstance` might also have further asssertions on the smart casted type... <@U12AGS8JG> 