Mockito returning null value for Future - mockito

Question

I am unit-testing a controller in a play-framework application.
The controller uses a repository and I am mocking the repository as follows
val mockUserRepository = mock(classOf[UsersRepository])
when(mockUserRepository.findOne(userKeys)).thenReturn(Future{Some(user)})
when(mockUserRepository.save(user)).thenReturn(Future(Some(user)))
Then I run the following test. In the test, controller.signupUser(request) calls the findOne method of the repository as follows
val findUserFuture: Future[Option[User]] = userRepo.findOne(userKeys)
println("user future is ",findUserFuture)
findUserFuture.flatMap { (userOption: Option[User]) => //this crashes because findUserFuture is null)
But findOne returns a null instead of a dummy Future{user}
"User signup request with body" should {
"return OK and user profile if the signup profile data is correct" in {
val jsonBody = Json.parse(
"""
{
"external-profile":{
"email":"test#test.com",
"firstname":"fn",
"lastname":"ln",
"password":"aA1!1111"
}
}
""")
//val jsonBody = Json.toJson(signupInfo)
val request: Request[AnyContentAsJson] = FakeRequest("POST", "ws/users/signup",Headers(("someH"->"someV")),new AnyContentAsJson(jsonBody))
println("sending sign up request ", request)
//request.body = signupInfo
val response: Future[Result] = controller.signupUser(request)
val responseBodyAsJsValue:JsValue = contentAsJson(response)
println("received response of sign up ", responseBodyAsJsValue)
}
}
error
received profile
UserProfile(None,ExternalUserProfile(test#test.com,fn,ln,Some(aA1!1111)))
checking if the user with the following details exists LoginInfo(credentials,test#test.com)
returning id 116 for name test#test.com
(user future is ,null)
java.lang.NullPointerException was thrown.
java.lang.NullPointerException
at controllers.UserController.$anonfun$signupUser$1(UserController.scala:116)
What I might be doing wrong?

Answer 1

The issue apparently was the I wasn't using when correctly.
I read that "
Mockito allows to configure the return values of its mocks via a fluent API. Unspecified method calls return "empty" values:
null for objects
0 for numbers
false for boolean
empty collections for collections
Mocks can return different values depending on arguments passed into a method. The when(…​.).thenReturn(…​.) method chain is used to specify a a return value for a method call with pre-defined parameters.
"
when expects the method as well as the exact arguments. So if I want to call findUser(userkey) where userkey's value is say 1 in the actual call then I need to write when(findUser(1)) or userKey=1; findUser(userKey)).
In my wrong implementation, I had set userkey as
UserKeys(1,"test#test.com",loginInfo,"","")
but the call to findUser was with value
UserKeys(116,"d#d.com",loginInfo,"fn","ln")
I changed the userkey value in test and it worked
val userKeys = UserKeys(utilities.bucketIDFromEmail(email)/*returns 116*/,"d#d.com",loginInfo,"fn","ln")
when(mockUserRepository.findOne(userKeys)).thenReturn(Future{Some(user)})
when(mockUserRepository.save(user)).thenReturn(Future(Some(user)))