How to test a try...finally method only been called once in SpringBoot? - spring-boot

Question

I am following this article to implement a database read/write separation feature by calling different methods. However, I got the error:
Missing method call for verify(mock) here: verify(spyDatabaseContextHolder, times(1)).set(DatabaseEnvironment.READONLY);
when doing the testing.
My test case is trying to verify DatabaseEnvironment.READONLY has been set once when using TransactionReadonlyAspect AOP annotation:
// TransactionReadonlyAspectTest.java
#RunWith(SpringRunner.class)
#ContextConfiguration(classes = {LoadServiceImpl.class, TransactionReadonlyAspect.class})
public class TransactionReadonlyAspectTest {
#Autowired
private TransactionReadonlyAspect transactionReadonlyAspect;
#MockBean
private LoadServiceImpl loadService;
#Test
public void testReadOnlyTransaction() throws Throwable {
ProceedingJoinPoint mockProceedingJoinPoint = mock(ProceedingJoinPoint.class);
Transactional mockTransactional = mock(Transactional.class);
DatabaseContextHolder spyDatabaseContextHolder = mock(DatabaseContextHolder.class);
when(mockTransactional.readOnly()).thenReturn(true);
when(loadService.findById(16)).thenReturn(null);
when(mockProceedingJoinPoint.proceed()).thenAnswer(invocation -> loadService.findById(16));
transactionReadonlyAspect.proceed(mockProceedingJoinPoint, mockTransactional);
verify(spyDatabaseContextHolder, times(1)).set(DatabaseEnvironment.READONLY); // got the error: Missing method call for verify(mock)
verify(loadService, times(1)).findById(16);
assertEquals(DatabaseContextHolder.getEnvironment(), DatabaseEnvironment.UPDATABLE);
}
}
//TransactionReadonlyAspect.java
#Aspect
#Component
#Order(0)
#Slf4j
public class TransactionReadonlyAspect {
#Around("#annotation(transactional)")
public Object proceed(ProceedingJoinPoint proceedingJoinPoint,
org.springframework.transaction.annotation.Transactional transactional) throws Throwable {
try {
if (transactional.readOnly()) {
log.info("Inside method " + proceedingJoinPoint.getSignature());
DatabaseContextHolder.set(DatabaseEnvironment.READONLY);
}
return proceedingJoinPoint.proceed();
} finally {
DatabaseContextHolder.reset();
}
}
}
// DatabaseContextHolder.java
public class DatabaseContextHolder {
private static final ThreadLocal<DatabaseEnvironment> CONTEXT = new ThreadLocal<>();
public static void set(DatabaseEnvironment databaseEnvironment) {
CONTEXT.set(databaseEnvironment);
}
public static DatabaseEnvironment getEnvironment() {
DatabaseEnvironment context = CONTEXT.get();
System.out.println("context: " + context);
return CONTEXT.get();
}
public static void reset() {
CONTEXT.set(DatabaseEnvironment.UPDATABLE);
}
}
//DatabaseEnvironment.java
public enum DatabaseEnvironment {
UPDATABLE,READONLY
}
// LoadServiceImpl.java
#Service
public class LoadServiceImpl implements LoadService {
#Override
#Transactional(readOnly = true)
public LoadEntity findById(Integer Id) {
return this.loadDAO.findById(Id);
}
...
}
I just want to test DatabaseContextHolder.set(DatabaseEnvironment.READONLY) has been used once then in the TransactionReadonlyAspect finally block it will be reset to DatabaseEnvironment.UPDATABLE which make sense.
However, how to test DatabaseContextHolder.set(DatabaseEnvironment.READONLY) gets called once? Why does this error occur? Is there a better way to test TransactionReadonlyAspect?