Springboot mockito mock a field - mockito

Question

I want to mock the TreeMap in Service class, I tried to mock using TreeMap<String, String> requestsMap = Mockito.mock(TreeMap.class); But the map is getting null at runtime.
#RunWith(SpringRunner.class)
#SpringBootTest
#WebAppConfiguration
public class ServiceTest {
#InjectMocks
private Service service;
#Before
public void init() {
MockitoAnnotations.initMocks(this);
}
#Test
public void test() {
TreeMap<String, String> requestsMap = Mockito.mock(TreeMap.class);
}
}
#Service
public class Service {
private TreeMap<String, String> requestsMap = null;
}

Answer 1

Your Service class doesn't actually do anything but declare and initialize the requestMap to null. Also, your test method doesn't do anything other than declare a mock requestMap.
In addition to the code you have, write a method in the Service that uses the request map and just declare/autowire the requestMap. In your test, use the #Mock annotation on a declaration of your mock requestMap. Finally, use the mocked requestMap in your test.
For example:
#RunWith(SpringRunner.class)
#SpringBootTest
#WebAppConfiguration
public class ServiceTest {
#Mock
TreeMap<String, String> requestsMap;
#InjectMocks
private Service service;
#Before
public void init() {
MockitoAnnotations.initMocks(this);
}
#Test
public void test() {
when(requestMap.get("foo")).thenReturn("bar");
String result = service.doSomething();
assertEquals(result, "bar");
}
}
#Service
public class Service {
#Autowired
private TreeMap<String, String> requestsMap;
public String doSomething() {
return requestMap.get("foo");
}
}