How to set the private member variable of a class in test method with powermock - junit

Question

I am writing a junit test for the below constructor. i tried to set the value of mapRecords variable using Membermodifier but still i get the zero as the size of list. being a newbie in junit i am not getting the exact idea to do it. if someone can help it would be appreciated.
public class Transform {
private MapMetadataDAO mapMetadataDAO;
private Map<String,String> srcTargetMap;
private List<MapMetadata> mapRecords;
public Transform(String transformationId) throws GenericFlowException {
try {
mapMetadataDAO=new MapMetadataDAO();
} catch (DAOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mapRecords = mapMetadataDAO.findMapMetadataByTransformationID(transformationId);
System.out.println(mapRecords.size());
if(mapRecords.isEmpty()){
throw new GenericFlowException("Map meta data is not defined for the transformationId "+transformationId);
}
map();
}
}
Test class :
If i don't create the object using new, i am not able to invoke the constructor
#RunWith(PowerMockRunner.class)
#PrepareForTest({Transform.class, MapMetadataDAO.class})
public class TransformTest {
#Test
public void constructorTest() throws Exception
{
PowerMockito.suppress(PowerMockito.constructor(MapMetadataDAO.class));
MapMetadataDAO dao = PowerMockito.mock(MapMetadataDAO.class);
MapMetadata mapMetaData = PowerMockito.mock(MapMetadata.class);
PowerMockito.whenNew(MapMetadataDAO.class).withNoArguments().thenReturn(dao);
List<MapMetadata> list = new ArrayList<>();
list.add(mapMetaData);
Transform trans = PowerMockito.mock(Transform.class, Mockito.CALLS_REAL_METHODS);
MemberModifier.field(Transform.class, "mapRecords").set(trans, list);
PowerMockito.when(dao.findMapMetadataByTransformationID("transformationID")).thenReturn(list);
Transform transform = new Transform("transformationId");
PowerMockito.whenNew(Transform.class).withAnyArguments().thenReturn(trans);
}
}

Answer 1

With some changes in your class I made it work
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
#RunWith(org.powermock.modules.junit4.PowerMockRunner.class)
#PrepareForTest({MapMetadataDAO.class, Transform.class})
public class TransformTest {
#Mock
private MapMetadataDAO mapMetadataDAO;
#Mock
private Map<String,String> srcTargetMap;
#InjectMocks
private Transform Transform = new Transform();
#Before
public void init() {
MockitoAnnotations.initMocks(this);
}
#Test
public void testConstructor() throws Exception {
List<MapMetadata> mapRecords = new ArrayList<MapMetadata>();
mapRecords.add(new MapMetadata());
PowerMockito.whenNew(MapMetadataDAO.class).withNoArguments().thenReturn(mapMetadataDAO);
PowerMockito.when(mapMetadataDAO.findMapMetadataByTransformationID(Mockito.anyString())).thenReturn(mapRecords);
Transform.getTransform("transformationId");
}
}
class Transform{
private MapMetadataDAO mapMetadataDAO;
private Map<String,String> srcTargetMap;
private List<MapMetadata> mapRecords;
public Transform() {}
public void getTransform(String transformationId){
try {
mapMetadataDAO=new MapMetadataDAO();
mapRecords = mapMetadataDAO.findMapMetadataByTransformationID(transformationId);
System.out.println(mapRecords.size());
if(mapRecords.isEmpty()){
throw new GenericFlowException("Map meta data is not defined for the transformationId "+transformationId);
}
map();
} catch (DAOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (GenericFlowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void map() {}
}
let me know if this is what you needed

Answer 2

For ease of test rewrite your class like this:
public class Transform {
private MapMetadataDAO mapMetadataDAO;
private Map<String,String> srcTargetMap;
private List<MapMetadata> mapRecords;
public Transform(MapMetadataDAO mapMedatadaDAO, String transformationId) throws GenericFlowException {
mapRecords = mapMetadataDAO.findMapMetadataByTransformationID(transformationId);
System.out.println(mapRecords.size());
if(mapRecords.isEmpty()){
throw new GenericFlowException("Map meta data is not defined for the transformationId "+transformationId);
}
map();
}
}
And then your test:
#RunWith(PowerMockRunner.class)
#PrepareForTest({MapMetadataDAO.class})
public class TransformTest {
#Test
public void constructorTest() throws Exception
{
MapMetadata mapMetaData = new MapMetadata();
List<MapMetadata> list = new ArrayList<>();
list.add(mapMetaData);
MapMetadataDAO dao = PowerMockito.mock(MapMetadataDAO.class);
String transformationId = "transformationId";
PowerMockito.when(dao.findMapMetadataByTransformationID(transformationId)).thenReturn(list);
Transform transform = new Transform(dao, transformationId);
}
}