[FIXED] Spring boot unit test not not working while returning hard coded values

Issue

I have below REST endpoint mapping.

@GetMapping("/employee/{id}")
public ResponseEntity<Employee> getEmployee(@PathVariable("id") int id) {
    Employee employee = employeeRepository.getEmployeeById (id);
    if(employee == null) {
        throw new EmployeeNotFoundException ();
    }
    ResponseEntity<Employee> responseEntity = new ResponseEntity<Employee> (employee, HttpStatus.OK);
    return responseEntity;
}

To test the failing path, I have the following test case.

@Test
public void getEmployeeFailTest() throws Exception {
    Mockito.when (employeeRepository.getEmployeeById (Mockito.anyInt ())).thenReturn (null);
    RequestBuilder requestBuilder = MockMvcRequestBuilders.get ("/employee/10")
            .accept (MediaType.APPLICATION_JSON);
    MvcResult result = mockMvc.perform (requestBuilder).andReturn ();
    String response = result.getResponse ().getContentAsString ();
    System.out.println (employeeRepository.getEmployeeById (5)==null);
    String expected = "{\"errorCode\":1,\"message\":\"404: Employee not found!\"}";
    JSONAssert.assertEquals (expected, response, false);
    Assert.assertEquals (404, result.getResponse ().getStatus ());
}

In the repository class, I am returning the hardcoded Employee object.

public Employee getEmployeeById(int i) {
    Employee employeeMock = new Employee (1, "XYZ","[email protected]",new Department (1, "HR"));
    return  employeeMock;
}

The test cases are passing successfully when I return null in the above method. But with the above implementation, it fails.

Thanks to Mockito.when (employeeRepository.getEmployeeById (Mockito.anyInt ())).thenReturn (null); getEmployeeById is returning null in test method but in controller's method above hardcoded Employee object is getting returned

Am I missing something?

Solution

1) If I understand your test correctly then you expect "404 not found" in response to "employee/10". When you return null then REST controller throws EmployeeNotFoundException (which I assume handled via exception handler and converted to 404). When you return non-null object then exception is not thrown and test fails.

I suggest your repository class emulates object not found by

public Employee getEmployeeById(int i) {
  return i==10 ? null : new Employee (1, "XYZ","[email protected]",new Department (1, "HR"));
} 

2) Mockito.when (employeeRepository.getEmployeeById (Mockito.anyInt ())).thenReturn (null); this code does not seem working. I assume you do not inject employeeRepository to REST properly. You should mark it with @MockBean in your test class so Spring Test will prefer it over real implementation

Answered By - Alexander Pavlov
Answer Checked By - Marie Seifert (JavaFixing Admin)