how to instantiate objects inside the class to be tested is an abstract class in Junit testing? - junit

Question

I have a class below for which I want to write a unit test
abstract class ProductImpl{
#Inject DataServices ds; // using Guice
public Response parse(String key, Long value){
Response res = ds.getResponseObject(); // Response object is created using DataServices object
res.id = key;
res.code = value;
}
}
And I have a test as below
class ProductImplTest{
#InjectMocks ProductImpl impl;
Map<String, Long> map;
#Before
map.put("abc", 10L);
map.put("xyz", 11L);
}
#Test
public void test(){
for(String key: map.keySet()){
Response res = impl.parse(key, map.get(key));
// and check if fields of Response object are set correctly i.e res.id is abc and value is 10L
}
}
But when i debug the test and control goes to parse method , DataServices object ds is null. How to instantiate this object through test . I do not want to use mocking, I want real response objects to be created and test the values set in them.

Answer 1

You can use Mockito
#RunWith(MockitoJUnitRunner.class)
class ProductImplTest {
#Mock DataService dService;
#InjectMocks ProductImpl sut;
#Test
public void test() {
ResponseObject ro = new ResponseObject();
String string = "string";
Long longVal = Long.valueOf(123);
sut.parse("string", longVal);
verify(dService).getResponseObject();
assertThat(ro.getId()).isEqualTo("string");
// you should use setters (ie setId()), then you can mock the ResponseObject and use
// verify(ro).setId("string");
}
}
EDIT:
With ResponseObject being an abstract class or preferably an interface, you'd have
interface ResponseObject {
void setId(String id);
String getId();
// same for code
}
and in your test
#Test public void test() {
ResponseObject ro = mock(ResponseObject.class);
// ... same as above, but
verify(dService).getResponseObject();
verify(ro).setId("string"); // no need to test getId for a mock
}

Answer 2

Try with constructor injection:
class ProductImpl{
DataServices ds;
#Inject
public ProductImpl(DataServices ds) {
this.ds = ds;
}
}