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Junit mockito when(..).thenReturn() throws NullPointerException

Asked 2012-08-15T12:52:49.293
8

Can anyone explain me the below scenario
Code to be tested
UserTransaction.java

@Override
public ServiceResponse<User> get(String name) {
    ServiceResponse<User> response = new ServiceResponse<User>();
    List<Map<String, Object>> exp = new ArrayList<Map<String, Object>>();
    Map<String, Object> map = new HashMap<String, Object>();
    map.put("expression", "eq");
    map.put("property", "name");
    map.put("value", name);
    exp.add(map);
    List<User> users = userDao.getByCriteria(exp);
    if (!users.isEmpty()) {
        response.setResponse(users.get(0));
    } else {
        response.setResponse(null);
    }
    return response;
}

UserDao.java

public List<User> getByCriteria(List<Map<String, Object>> exp) {
  DetachedCriteria criteria = DetachedCriteria.forClass(User.class);
  for (Integer i=0;i<exp.size();i++){
    String expression = (String) exp.get(i).get("expression");
    String property = (String) exp.get(i).get("property");
    if(expression.equals("eq"){
       criteria.add(Restrictions.eq(property,exp.get(i).get("value")));
    }
  }
  return hibernateTemplate.findByCriteria(criteria);
 }

UserTransactionTest.java

private UserTransaction userTransactions = new UserTransaction();
private UserDao userDao = mock(UserDao.class);

@Test
public void testGet() {
   User user = new User();
   user.setName("Raman");
    try {
        when(userDao.getByCriteria(anyList())).thenReturn(user);
    } catch (Exception e) {
        e.printStackTrace();
    }
    ServiceResponse<User> response = userTransactions.get("raman");
    User result = response.getResponse();
    assertEquals("Raman", result.getName());
    assertEquals(0, response.getErrors().size());
}

works fine.

But instead of "anyList()" I passed a user-defined list "myList"

java unit-testing junit mockito
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1 Answer

6

I'm sure you've already solved your problem by now, but in case anyone stumbles upon the same issue, here's the answer:

In the code you've provided, you are not using the mocked myList you've created. The get() method always calls userDao.getByCriteria(exp), a local variable.

This is why anyList() works, while myList doesn't.

If you do want to test the expression, List<Map<String,Object>> exp should be a member of your class, not a local variable:

public class UserTransaction {
    private List<Map<String,Object>> exp;

    public UserTransaction() {
        // creating a default exp value
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("expression", "eq");
        map.put("property", "name");
        map.put("value", name);
        exp.add(map);
    }

    // getters and setters for exp

    public ServiceResponse<User> get(String name) {
        ServiceResponse<User> response = new ServiceResponse<User>();
        List<User> users = userDao.getByCriteria(exp);
        if (!users.isEmpty()) {
            response.setResponse(users.get(0));
        } else {
            response.setResponse(null);
        }
        return response;
    }
}

And in your Test:

private UserTransaction userTransactions = new UserTransaction();
private UserDao userDao = mock(UserDao.class);

@Test
public void testGet() {
    User user = new User();
    user.setName("Raman");

    // creating a custom expression
    List<Map<String,Object>> myList = new ArrayList<Map<String,Object>>();
    Map<String,Object> map = new HashMap<String,Object>();
    map.put("expression","eq");
    map.put("property","name");
    map.put("value","raman");
    myList.add(map);

    // replacing exp with the list cre
answered 2013-08-05T14:15:06.667

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