How does assert groupType != null contain 4 branches

问题:

I need to test the following code.

public List<PatientGroup> findGroups(final String groupType) throws HwBaseAppException {     assert groupType != null;//4 branches here     CriteriaBuilder criteriaBuilder=persistence.getCriteriaBuilder();     CriteriaQuery<PatientGroup> query = criteriaBuilder.createQuery(PatientGroup.class);     Root<PatientGroup> patientGroupRoot = query.from(PatientGroup.class);     Predicate condition=criteriaBuilder.equal(patientGroupRoot.get(PatientGroup_.active), Boolean.TRUE);     Join<PatientGroup, GroupSubType> groupSubTypeRoot = patientGroupRoot.join(PatientGroup_.groupSubType);     Predicate condition1=criteriaBuilder.equal(groupSubTypeRoot.get(GroupSubType_.groupTypeCode), groupType);     query.where(condition,condition1);     query.orderBy(criteriaBuilder.asc(patientGroupRoot.get(PatientGroup_.name)));     TypedQuery<PatientGroup> tq = persistence.createQuery(query);            List<PatientGroup> collections = tq.getResultList();     return initializeGroupRelationships(collections); } 

In my test case i am passing both null and not null values which should cover both the branches however Code coverage says 1 of 4 branches missed.What are the other 2 branches? Below are my test cases.

 @Test     public void testFindGroups_1()         throws HwBaseAppException     {            Mockito.when(persistence.getCriteriaBuilder()).thenReturn(criteriaBuilder);         Mockito.when(criteriaBuilder.createQuery(PatientGroup.class)).thenReturn(criteriaQuery);         Mockito.when(criteriaQuery.from(PatientGroup.class)).thenReturn(patientGroupRoot);         Mockito.when(patientGroupRoot.join(PatientGroup_.groupSubType)).thenReturn(groupSubTypeRoot);         Mockito.when(persistence.createQuery(Mockito.any(CriteriaQuery.class))).thenReturn(tq);         Mockito.when(tq.getResultList()).thenReturn(arrayList);         Mockito.when(arrayList.iterator()).thenReturn(iterator);         Mockito.when(iterator.hasNext()).thenReturn(true).thenReturn(false);         Mockito.when(iterator.next()).thenReturn(patientGroup);         groupServiceDAOImpl.findGroups("groupType");         }     @Test(expected=AssertionError.class)     public void testFindGroups_2()         throws HwBaseAppException     {            groupServiceDAOImpl.findGroups(null);        } 

回答1:

EclEmma Eclipse plugin provides coverage analysis using JaCoCo library, which in his turn analyzes bytecode. Let's take a simplified example:

class Example {   void example(Object x) {     assert x != null;   } } 

And let's have a look on its bytecode:

javac Example.java javap -v Example 

Which looks like:

 0: getstatic     #2                  // Field $assertionsDisabled:Z  3: ifne          18  6: aload_1  7: ifnonnull     18 10: new           #3                  // class java/lang/AssertionError 13: dup 14: invokespecial #4                  // Method java/lang/AssertionError."<init>":()V 17: athrow 18: return 

As you can see - there are actually 2 conditions:

1. assertions enabled (ifne)
2. x is not null (ifnonnull)

And so 4 possible variants.

文章来源: How does assert groupType != null contain 4 branches