How do we verify method that has lambda function as its argument?

Question

So I have this main() method that calls printResult() method and the printResult() has a lambda argument on second parameter like this:

class SomeClass() {

   fun main(value: Int) {
      printResult(value){ it ->
         it + it
      }
   }
 
   fun printResult(value: Int, sum: (Int) -> Int) {
      val result = sum(value)
      println(result)
   }
}

Then in the unit test, I want to verify that every time the main() method is called, the printResult() should be invoked as well. So I write the unit test like this:

@Test
fun testMain_shouldInvokePrintResult() {
   someClass.main(10)
   verify(someClass).printResult(10){ any() }
}

I don't know what argument I should pass for printResult() method, that's why I used any(). But when I run the test, the compiler said:

Argument(s) are different! Wanted:
someClass.main(
    10,
    () (kotlin.Exception /* = java.lang.Exception */) -> kotlin.Unit
);
-> at com.mydomain.test.testMain_shouldInvokePrintResult(SomeClassTest.kt:49)
Actual invocations have different arguments:
someClass.main(
    10,
    () (kotlin.Exception /* = java.lang.Exception */) -> kotlin.Unit
);
-> at com.mydomain.SomeClass.printResult$lambda-27(SomeClass.kt:20)

So the compiler basically said different arguments but showed me no different on both invocation. What should I do? any help would be appreciated..

Answer 1

It solved. So my colleagues told me to use any() inside parenthesis instead of the curly brackets. So it would be like this:

@Test
fun testMain_shouldInvokePrintResult() {
   someClass.main(10)
   verify(someClass).printResult(10, any())
}