How to mock nested methods in Java

Question

In order to test my program I need to mock a method call like:

entityManager.createQuery("SELECT...", Integer.class).getSingleResult()

the createQuery part returns a TypedQuery<Integer>, but I actually just want to return a single integer: 1. Currently I am using Mockito in order to create my mocks and I am pretty new to this.

Is there a way of testing this?

Thank you!

Answer 1

Assuming you have class EntityManager, Query. You can mock your test like below. (mock(), any(), when() ... methods are in Mockito)

int result = 1;
Query query = mock(Query.class);
EntityManager entityManager = mock(EntityManager.class);

when(entityManager.createQuery(any(), any()).thenReturn(query);
when(query.getSingleResult()).thenReturn(result);