JdbcTemplate Mockito ClassCastException - spring

Question

I am trying to mock a method of the Spring framework's JdbcTemplate class. The method has the following signature:
public <T> T queryForObject(String sql, Class<T> requiredType) throws DataAccessException {...}
The mocking is being done as mentioned below:
when(jdbcTemplate.queryForObject(anyString(), eq(String.class))).thenReturn("data");
However, this call throws the following exception
java.lang.ClassCastException: org.mockito.internal.creation.jmock.ClassImposterizer$ClassWithSuperclassToWorkAroundCglibBug$$EnhancerByMockitoWithCGLIB$$ce187d66 cannot be cast to java.lang.String
at test.DaoJdbcTest.setUp(DaoJdbcTest.java:81)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
...
Any idea as to what I am doing wrong?
Thanks in advance~
EDIT:
Here's the full code:
public class DaoJdbc extends NamedParameterJdbcSupport {
public String query(String sql) {
return getJdbcTemplate().queryForObject(sql, String.class);
}
}
public class DaoJdbcTest {
#Mock(answer = Answers.RETURNS_SMART_NULLS)
private JdbcTemplate jdbcTemplate;
private DaoJdbc dao;
#Before
public void setUp() throws Exception {
MockitoAnnotations.initMocks(this);
dao = new DaoJdbc();
dao.setJdbcTemplate(jdbcTemplate);
Mockito.when(jdbcTemplate.queryForObject(anyString(), Matchers.eq(String.class))).thenReturn("data");
}
#Test
public void testQuery() {
String ret = dao.query("select 'test' from dual");
assertEquals("data", ret);
verify(jdbcTemplate).queryForObject(anyString(), eq(String.class));
}
}

Answer 1

Remove the answer = Answers.RETURNS_SMART_NULLS. Test passes when I remove that. What does that feature do? The default null behavior works fine for me.
As a bonus, you can also use the MockitoJunitRunner to clean up the code a bit...
#RunWith(MockitoJUnitRunner.class)
public class DaoJdbcTest {
#Mock
private JdbcTemplate jdbcTemplate;
#InjectMocks
private DaoJdbc dao;
#Before
public void setUp() throws Exception {
Mockito.when(jdbcTemplate.queryForObject(anyString(), Matchers.eq(String.class))).thenReturn("data");
}
#Test
public void testQuery() {
String ret = dao.query("select 'test' from dual");
assertEquals("data", ret);
verify(jdbcTemplate).queryForObject(anyString(), eq(String.class));
}
}