(kotlin) Mockito helper to mock a method with a context

Question

I use mockito-kotlin, which is super great to do this kind of code, with myMethod being a suspend function:

mock(MyClass) {
  onBlocking { myMethod() }.doReturn("hi")
}

Now I'd like to use a context receiver in myMethod, like

context(MyContext)
suspend fun myMethod() {
 ...
}

The mock definition now doesn't compiler anymore because it expects a context, so I could do:

mock(MyClass) {
  onBlocking { 
    with(MyContext) {
      myMethod() 
    }
  }.doReturn("hi")
}

which works fine, but I have the same piece of code at 50 places, so I'd like to define a helper method that provided the context automatically. The best I could achieve is (this is mostly a copy-paste of the original onBlocking method):

fun <T : Any, R> KStubbing<T>.onBlockingContext(
    m: suspend context(MyContext) T.() -> R
): OngoingStubbing<R> {
    val context = any<MyContext>()
    return runBlocking {
        with(context) {
            Mockito.`when`(m([email protected]))
        }
    }
}

However at runtime I have the following error:

java.lang.ClassCastException: class MyClass cannot be cast to class MyContext (MyClass and MyContext are in unnamed module of loader 'app')

Any idea how I could make it work - or another way to put the code in common?