Junit for QueryDsl - mockito

Question

I'm trying to write a test case for a query dsl, I'm getting null pointer exception when I run the test case
Dsl Class
QMyClass myClass= QMyClass.myClass;
queryFactory = new JPAQueryFactory(em);
JPAQuery<?> from = queryFactory.from(myClass);
JPAQuery<?> where = from
.where(prepdicates);
orderBy(orderSpecifier).offset(sortOrder.getOffset())
.limit(sortOrder.getPageSize());
**Junit test case:**
import javax.inject.Provider;
import javax.persistence.EntityManager;
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.modules.junit4.PowerMockRunner;
import org.springframework.data.jpa.repository.support.QueryDslRepositorySupport;
import com.querydsl.core.types.OrderSpecifier;
import com.querydsl.core.types.Predicate;
import com.querydsl.jpa.JPQLTemplates;
import com.querydsl.jpa.impl.JPAQuery;
import com.querydsl.jpa.impl.JPAQueryFactory;
#RunWith(PowerMockRunner.class)
public class MyClass{
#Mock
QueryDslRepositorySupport queryDslRepositorySupport;
#Mock
EntityManager entityManager;
#Mock
JPAQueryFactory queryFactory;
#Mock
JPAQuery step1;
#InjectMocks
MyClass myClass;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
Provider<EntityManager> provider = new Provider<EntityManager>() {
#Override
public EntityManager get() {
return entityManager;
}
};
queryFactory = new JPAQueryFactory(JPQLTemplates.DEFAULT, provider);
}
#SuppressWarnings({ "rawtypes", "unchecked" })
#Test
public void sampleTest() throws Exception {
QMyClass class= Mockito.mock(QMyClass.class);
Mockito.when(queryFactory.from(class)).thenReturn(step1);
Predicate step2 = Mockito.mock(Predicate.class);
Mockito.when(step1.where(step2)).thenReturn(step1);
OrderSpecifier step3 = Mockito.mock(OrderSpecifier.class);
Mockito.when(step1.orderBy(step3)).thenReturn(step1);
Mockito.when(step1.offset(Mockito.anyLong())).thenReturn(step1);
Mockito.when(step1.limit(Mockito.anyLong())).thenReturn(step1);
myClass.method("");
}
}
When I run this test case I'm getting null pointer exception at line number 2 in sampleTest() method. I googled but did't find any article for this, not sure why this NE, even after mocking the queryfacotry
Here is the trace :
java.lang.NullPointerException
at com.querydsl.core.DefaultQueryMetadata.addJoin(DefaultQueryMetadata.java:154)
at com.querydsl.core.support.QueryMixin.from(QueryMixin.java:163)
at com.querydsl.jpa.JPAQueryBase.from(JPAQueryBase.java:77)
at com.querydsl.jpa.impl.JPAQueryFactory.from(JPAQueryFactory.java:116)
at

Answer 1

As I mentioned in the comment, your problem is that you do not use a mock, but the real object instead.
Remove the queryFactory initialisation from your setup method.
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
Provider<EntityManager> provider = new Provider<EntityManager>() {
#Override
public EntityManager get() {
return entityManager;
}
};
// remove this line
// queryFactory = new JPAQueryFactory(JPQLTemplates.DEFAULT, provider);
}
Also you need to change your implementation, you can not use
queryFactory = new JPAQueryFactory(em); inside your code, as it can not be mocked.
What you could do instead is having a method that returns the JPAQueryFactory,
either from another class - which you can mock -
or in the same method, then you would need to spy on your class instead.
As you didnt add the code for the class you want to test (MyClass - hopefully a different one from the identical named UnitTest?), another possibility would be that you try to use Field or Constructor Injection (as indicated by the use of your annotations), but then there should not be an object creation for the JPAQueryFactory in your code at all.
This also seems to be wrong:
You should inject mocks into your class under test, not in your UnitTest class.
#RunWith(PowerMockRunner.class)
public class MyClass{
...
#InjectMocks
MyClass myClass;