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kotlinlang

I want to test that calling a given method on my subject/unit under test calls a given method on a mock, with any lambda as an argument. However if I do this:

```subject.openThePodBayDoors()

verify(mockDoorManager).completion(Mockito.any())
```
 ...then I get an error:
```java.lang.IllegalStateException: Mockito.any() must not be null```
...even though I have written the production code which should make this test pass.

I’ve been googling “kotlin mockito match any lambda” etc. and can find complex tests with `LambdaMatcher` but all I want to do is check that the method was called with _some_ lamba - I don’t even care what it does for this test. There must be a simple solution for this I’m missing, surely?

I’ve also tried:

```verify(mockDoorManager).completion(argThat(ArgumentMatcher { true } ))```

...but get exactly the same runtime error