[FIXED] mocking a recursive class

Issue

using Spring 2.0.3.RELEASE, JUnit Jupiter 5.7.0, Mockito 3.3.3

try to test method method01 of class Class01:

public class Class01 {

 private RestConnector con;
 
 public Class01(){
  con = RestConnector.getInstance();
 }

 public Response method01(String x) {
  Class01 example = new Class01();
  String x = example.isAuthenticated();
  
  // more stuff after this
  
 }
 
 public String isAuthenticated() throws IOException {
  // I do stuff
  return "a string";
 }

}  

In the test class have tried

public class Class01Test{

 @Mock private Class01 class01Mock;
 
 @Spy @InjectMocks private Class01 class01;

 @Test
 public void test() throws Throwable {
  
  doReturn("I returned").when(class01).  ??? stuck here .. always goes into the isAuthenticated method
  Response result = class01.method01("a string");
 }

}

Currently the test is always running the real method isAuthenticated. How to setup a mock for the field example in method method01 so that the execute skips going into method isAuthenticated?

Solution

try to test method method01 of class Class01

Then you don't need mocks.

 @Test
 public void test() throws Throwable {
  Class01 c = new Class01();

  Response expected = ... ;
  assertEquals(c.method01("input"), expected);
 }

If you want to inject behaviour into example variable, you need to move it to a field

public class Class01 {

 private RestConnector con;
 private Class01 inner;
 
 public Class01(){
  con = RestConnector.getInstance();
 }

 Class01(Class01 c) {
   this();
   this.inner = c;
 }

 public Response method01(String x) {
  String x = inner.isAuthenticated();
  
  // more stuff after this
  
 }

Along with a Mock

@RunWith(MockitoJunitRunner.class)
public class Class01Test{

 @Mock Class01 class01Mock;

 @Test
 public void test() throws Throwable {
  Response expected = ... ;
  when(class01Mock.isAuthenticated()).thenReture(expected); ... // TODO: Setup  
 
  Class01 c = new Class01(class01Mock); // pass in the mock
  
  assertEquals(c.method01("input"), expected);
 }

However, unclear why you need a nested object of the same class when you appear to only need this.isAuthenticated()

Ideally, you'd also mock the RestConnector

Answered By - OneCricketeer
Answer Checked By - Mary Flores (JavaFixing Volunteer)