Spring-Boot | Test Service Containing Call to #Async Method - spring-boot

Question

Want to Unit Test a Service that contains call to a #Aysnc method which return CompletableFuture Object.But the future object is always null (during testing) causing NullPointerException.
future.get() causes the error
Test Code
#RunWith(MockitoJUnitRunner.class)
public class ContainerValidatorTest {
#Mock
QueryGenerator queryGenerator;
#Mock
SplunkService splunkService;
#InjectMocks
private ContainerValidatorImpl containerValidatorImpl;
#Test
public void validateContainerTestWithNullData(){
CacheItemId cacheItemId = null;
String container = null;
assertFalse(containerValidatorImpl.validateContainer(cacheItemId,container));
}
}
Service Code
#Override
public boolean validateContainer(CacheItemId cacheItemId, String container) {
Query query = queryGenerator.getUserDetailsFromCacheInfoQuery(cacheItemId);
String response;
try {
CompletableFuture<String> future = splunkService.doExecuteQuery(query);
response = future.get();
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("Error While Fetching User Details : "+ e.getLocalizedMessage());
}
System.out.println(response);
JsonArray jsonArray = new JsonParser().parse(response).getAsJsonArray();
if(!jsonArray.isJsonNull()) {
return jsonArray.get(0).getAsJsonObject().get("TAG").getAsString().equalsIgnoreCase(container);
}
throw new RuntimeException("Not Able to Find UserDetails");
}

Answer 1

You haven’t set any expectations on splunkService mock.
Then you call doExecuteQuery on the mock instance
With no expectations for the method call, Mockito returns default value for the method return type (null for Objects)
To fix, record your expectations with when and thenReturn
Update
#Test
public void validateContainerTestWithNullData(){
CacheItemId cacheItemId = null;
String container = null;
when(splunkService.doExecuteQuery(any())).thenReturn(CompletableFuture.completedFuture("completedVal"));
assertFalse(containerValidatorImpl.validateContainer(cacheItemId,container));
}