Testing Spring JDBC with JMockit with JUnit4

Question

I am testing a Spring JDBC class using the JMockit. The following is the test class:

public class DAOImplTest {

@Tested
DAOImpl daoImpl;

@Mocked
JdbcTemplate mockJdbcTemplate;

@Before
public void setup() throws Exception{
    daoImpl = new DAOImpl();
    daoImpl.setJdbcTempate(mockJdbcTemplate);
}

@Test
public void testGetSomeString() throws Exception{
    final String expectedO = "7c82facc";
    final String expectedG = "one";

    new Expectations() {{
        mockJdbcTemplate.queryForObject(SSODAOImpl.GET_IDS, String.class, expectedO);
        result = expectedG;
    }};

    DAOImpl daoImpl = new DAOImpl();
    String actual = daoImpl.getSomeString(expectedO);
    assertEquals(expected, actualG);
}

}

The class is throwing NullPointer Exception on line String actual = daoImpl.getSomeString(expectedO)

What's the reason for getting the null pointer exception at the very point?

The following is the DAOImpl class method:

public String getSomeString(String or) {
DAORowMapper rowMapper = new DAORowMapper();
            String g = jdbcTemplate.queryForObject(GET_IDS, rowMapper, orgIds);
            return g;
}

Here is the stack trace while running the JUnit 4 Test. Again the NullPointer exception is when running the Junit4 Test Case

java.lang.NullPointerException
    at com.DAOImpl.getSomeString(DAOImpl.java:31)
    at comDAOImplTest.testGetSomeString(DAOImplTest.java:45)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:597)

Answer 1

Seems like the problem is that within getSomeString() the jdbcTemplate field is null. This is because while you set this field on the daoImpl field in the setup() method, you are not using the daoImpl field....you are shadowing the field with a local variable here:

DAOImpl daoImpl = new DAOImpl();

This local variable doesn't have the jdbcTemplate field set to the mock object. Remove that line and I'm thinking it will work.