Develop Reference

Spring bean scope for "one object per test method"

I have a test utility for with I need to have a fresh instance per test method (to prevent that state leaks between tests). So far, I was using the scope "prototype", but now I want to be able to wire the utility into another test utility, and the wired instances shall be the same per test.
This appears to be a standard problem, so I was wondering if there is a "test method" scope or something similar?
This is the structure of the test class and test utilities:
#RunWith(SpringRunner.class)
#SpringBootTest
public class MyTest {
#Autowired
private TestDriver driver;
#Autowired
private TestStateProvider state;
// ... state
// ... methods
}
#Component
#Scope("prototype") // not right because MyTest and TestStateProvider get separate instances
public class TestDriver {
// ...
}
#Component
public class TestStateProvider {
#Autowired
private TestDriver driver;
// ...
}
I'm aware that I could use #Scope("singleton") and #DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD) but this refreshes more than I need – a new TestDriver instance for each test would be enough. Also, this approach is error-prone because all tests using the TestDriver would need to know that they also need the #DirtiesContext annotation. So I'm looking for a better solution.

It is actually pretty easy to implement a testMethod scope:
public class TestMethodScope implements Scope {
public static final String NAME = "testMethod";
private Map<String, Object> scopedObjects = new HashMap<>();
private Map<String, Runnable> destructionCallbacks = new HashMap<>();
#Override
public Object get(String name, ObjectFactory<?> objectFactory) {
if (!scopedObjects.containsKey(name)) {
scopedObjects.put(name, objectFactory.getObject());
}
return scopedObjects.get(name);
}
#Override
public void registerDestructionCallback(String name, Runnable callback) {
destructionCallbacks.put(name, callback);
}
#Override
public Object remove(String name) {
throw new UnsupportedOperationException();
}
#Override
public String getConversationId() {
return null;
}
#Override
public Object resolveContextualObject(String key) {
return null;
}
public static class TestExecutionListener implements org.springframework.test.context.TestExecutionListener {
#Override
public void afterTestMethod(TestContext testContext) throws Exception {
ConfigurableApplicationContext applicationContext = (ConfigurableApplicationContext) testContext
.getApplicationContext();
TestMethodScope scope = (TestMethodScope) applicationContext.getBeanFactory().getRegisteredScope(NAME);
scope.destructionCallbacks.values().forEach(callback -> callback.run());
scope.destructionCallbacks.clear();
scope.scopedObjects.clear();
}
}
#Component
public static class ScopeRegistration implements BeanFactoryPostProcessor {
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory factory) throws BeansException {
factory.registerScope(NAME, new TestMethodScope());
}
}
}
Just register the test execution listener, and there will be one instance per test of all #Scope("testMethod") annotated types:
#RunWith(SpringRunner.class)
#SpringBootTest
#TestExecutionListeners(listeners = TestMethodScope.TestExecutionListener.class,
mergeMode = MergeMode.MERGE_WITH_DEFAULTS)
public class MyTest {
#Autowired
// ... types annotated with #Scope("testMethod")
}

I ran into the same problem some time ago and came to this solution:
Use Mocks
I wrote some methods to create specific mockito settings to add behavior to each mock.
So create a TestConfiguration class with following methods and bean definition.
private MockSettings createResetAfterMockSettings() {
return MockReset.withSettings(MockReset.AFTER);
}
private <T> T mockClass(Class<T> classToMock) {
return mock(classToMock, createResetAfterMockSettings());
}
and your bean definition will look like:
#Bean
public TestDriver testDriver() {
return mockClass(TestDriver .class);
}
MockReset.AFTER is used to reset the mock after the test method is run.
And finally add a TestExecutionListeners to your Test class:
#TestExecutionListeners({ResetMocksTestExecutionListener.class})

Mockito is not mocking out a member variable method return value

I have the following class that contains a member variable, but Mockito can't seem to mock the member variable's methods. Below is my System Under Test:
public class MessageConsumer {
private ConsumerResponse consumerResponse;
private NotificationConsumer notificationConsumer;
#Scheduled(cron = "${com.example.value}")
public void fetch() {
consumerResponse = notificationConsumer.fetchWithReturnConsumerResponse(); //no exception thrown on this line at all -- but could this be the cause of the problem in the test?
System.out.println("consumerResponse's responseCode: " + consumerResponse.getResponseCode()); // NullPointerException thrown here
}
public ConsumerResponse setConsumerResponse(ConsumerResponse consumerResponse) {
this.consumerResponse = consumerResponse;
}
public ConsumerResponse getConsumerResponse() {
return consumerResponse;
}
}
And the following is the relevant JUnit test for the class:
#SpringBootTest
#RunWith(MockitoJUnitRunner.class)
public class MessageConsumerTest {
#Mock
private ConsumerResponse consumerResponse;
#InjectMocks
private MessageConsumer messageConsumer;
#Before
public void setup() {
MockitoAnnotations.initMocks(this);
}
//Failing unit test
#Test
public void getResponseCodeShouldReturn200() {
Mockito.when(consumerResponse.getResponseCode()).thenReturn("200");
messageConsumer.fetch()
}
}
As you can see, I've mocked the ConsumerResponse consumerResponse variable to return "200" when the consumerResponse.getResponseCode() method gets invoked. Instead, I'm getting a NullPointerException.
I'm pretty sure I mocked the member variable correctly and initialized it appropriately (initMocks). I've spent days trying to figure this out. Where am I going wrong?

As NotificationConsumer is also an external dependency for this class, you have to also mock this class as otherwise consumerResponse = notificationConsumer.fetchWithReturnConsumerResponse(); will result into null within your test as you didn't mock the NotificationConsumer. In addition I would suggest not to use #SpringBootTest within this unit test as this annotation will boot the whole Spring context. The following snippet should help you:
#RunWith(MockitoJUnitRunner.class)
public class MessageConsumerTest {
#Mock
private ConsumerResponse consumerResponse;
#Mock
private NotificationConsumer notificationConsumer;
#InjectMocks
private MessageConsumer messageConsumer;
#Before
public void setup() {
MockitoAnnotations.initMocks(this);
}
#Test
public void getResponseCodeShouldReturn200() {
Mockito.when(notificationConsumer.fetchWithReturnConsumerResponse()).thenReturn(consumerResponse);
Mockito.when(consumerResponse.getResponseCode()).thenReturn("200");
messageConsumer.fetch();
}
}

#Autowired dependencies is not getting initialized in base class

I have a test class which is testing an other class method
Other class is structured like this
#Component
public abstract class ParentOpManager{
#Autowired
private ProcessorRequestWrapper processorRequestWrapper;
#Autowired
private XYProcessor xyProcessor;
}
#Component("childManager")
public class ChildOperationManager extends ParentOpManager{
}
public abstract class ParentClass{
protected final RequestWrapper requestWrapper;
protected final ParentOpManager parentOpManager;
public ParentClass(final RequestWrapper requestWrapper, final ParentOpManager parentOpManager){
this.requestWrapper = requestWrapper;
this.parentOpManager = parentOpManager;
}
}
further I have, child classes extending this class
public class ChildClass extends ParentClass{
#Autowired
private NinjaManager ninjaManager;
#Autowired
public ChildClass(final RequestWrapper requestWrapper, #Qualifier("childManager")final ParentOpManager parentOpManager){
super(requestWrapper, parentOpManager);
}
public void methodA() throws Exception {
Request item = requestWrapper.findItem(); // Problem place 1
}
public void methodB() throws Exception {
Request item = ninjaManager.findItem(); // Problem place 2
}
}
I need to test methods of ChildClass. For this I have written a test class.
//#RunWith(MockitoJunitRunner.class)
//#ContextConfiguration
public class TestClass{
#Mock
ChildOperationManager chOpManager;
#Mock
RequestWrapper requestWrapper;
#InjectMocks
ChildClass childObject;
#Before
public void setup(){
MockitoAnnotations.initMocks(this);
}
#Test
public void testSomeMethodA() throws Exception{
childObject.methodA();
}
}
So, the problem is when I am class methodA from test class, requestWrapper is NULL. I can not understand why this is happening ?
EDIT:
If i do like
#Mock
ChildOperationManager chOpManager = new ChildOperationManager();
#Mock
RequestWrapper requestWrapper;
#InjectMocks
ChildClass childObject = new childObject(requestWrapper, chOpManager);
Problem seams to be resolved. There is some other problem which might be some permission issue. But do you think doing this way is good approach ?

Your error is this:
#Autowired
public ChildClass(final RequestWrapper requestWrapper, #Qualifier("childManager")final ParentOpManager parentOpManager){
super(requestWrapper, parentOpManager);
}
public void methodA() throws Exception {
Request item = requestWrapper.findItem(); // this requestWrapper is null
}
You don't assign the requestWrapper reference in the child. So it remains null.
You should just remove the member variable requestWrapper and parentOpManager from the child. this way, you'll use the parent's one, which is initialized.

Problem is that Mockito tried to inject mock via constructor in first step.
public class DefaultInjectionEngine {
public void injectMocksOnFields(Set<Field> needingInjection, Set<Object> mocks, Object testClassInstance) {
MockInjection.onFields(needingInjection, testClassInstance)
.withMocks(mocks)
.tryConstructorInjection() <-- Here
.tryPropertyOrFieldInjection()
.handleSpyAnnotation()
.apply();
}
}
And if it found proper constructor, it doesn't try to inject mocks via property or field.
In your case you have constructor for ChildClass, which was picked by Mockito, but you don't initialize a fields in ChildClass.
As workaround, you can resolve it in this way (just don't use mockito injections):
RequestWrapper wrapper;
ChildOperationManager childOperationManager;
ChildClass childObject;
#Before
public void setUp() {
wrapper = Mockito.mock(RequestWrapper.class);
childOperationManager = Mockito.mock(ChildOperationManager.class);
childObject = new ChildClass(wrapper, childOperationManager );
}

Using #InjectMocks to replace #Autowired field with a mocked implementation

I want to replace an autowired class of a service in my spring boot app with a mocked implementation of that class that I created specifically for testing.
I chose to create this mocked implementation because the behaviour of this class is too complicated to mock using mockito as it requires multiple other mocks itself.
I am not able to work out how to inject this mocked implementation into the service.
Here is a minimal example of the situation:
#Service
public class ServiceIWantToTestImpl implements ServiceIWantToTest{
#Autowired
ComplicatedDependency complicatedDependency;
#Override
public void methodUsingDependency(){
String string = complicatedDependency.doSomething();
System.out.println(string);
}
}
public class MockComplicatedDependency implements ComplicatedDepencency{
public MockComplicatedDependency(...){
// Inject other mocked objects into this mock
}
public String doSomthing(){
// This would be a mocked version of this function for testing
return "test";
}
}
#RunWith(MockitoJUnitRunner.class)
public class TestingTheService(){
#InjectMock
private static ServiceIWantToTest serviceIWantToTest = new ServiceIWantToTestImpl();
#Mock
ComplicatedDependency mockComplicatedDependency;
#BeforeClass
public static void init(){
mockComplicatedDependency = new MockComplicatedDependency(...);
}
#Test
public void testAttempt(){
serviceIWantToTest.methodUsingDependency(); // This method calls complicatedDependency.doSomething() which does not run the mocked version in MockComplicatedDependency which I wanted to inject, and would always return null instead of the "test" string I put in this example.
}
}

Do you have to use Mockito annotations to setup dependencies for the class under test?
If that is not the main constraint why not just do the plain simple setup and introduce a constructor or a setter in ServiceIWantToTestImpl class for the ComplicatedDependency field and set the dependency in your test setup directly to whatever impl of ComplicatedDependency you like e.g.:
#Service
public class ServiceIWantToTestImpl implements ServiceIWantToTest {
#Autowired
ComplicatedDependency complicatedDependency;
public ServiceIWantToTestImpl() {
}
public ServiceIWantToTestImpl(ComplicatedDependency complicatedDependency) {
this.complicatedDependency = complicatedDependency;
}
#Override
public void methodUsingDependency(){
String string = complicatedDependency.doSomething();
System.out.println(string);
}
}
public class TestingTheService {
private static ServiceIWantToTestImpl serviceIWantToTest;
#BeforeClass
public static void init(){
serviceIWantToTest = new ServiceIWantToTestImpl(new MockComplicatedDependency());
}
#Test
public void testAttempt() {
serviceIWantToTest.methodUsingDependency();
}
}
That is one way.
To make it work with Mockito, You could to use #Spy instead of #Mock like this:
#RunWith(MockitoJUnitRunner.class)
public class TestingTheService {
#InjectMocks
private static ServiceIWantToTestImpl serviceIWantToTest = new ServiceIWantToTestImpl();
#Spy
private static ComplicatedDependency complicatedDependency = new MockComplicatedDependency();
#BeforeClass
public static void init() {
}
#Test
public void testAttempt() {
serviceIWantToTest.methodUsingDependency();
}
}
Though this is a bit of a hack. I strongly recommend that you read the JavaDoc of the #Spy annotation and make sure it's expected use is what you really need for your test.

How to tell a Mockito Mock annotation to return a mock object which is not null?

I am trying to unit test a method, which has different branches depending upon the value of an object that is created inside it. The below code demonstrates it.
public class AClass {
public void method2() {
//Some code goes here
}
public void method1(BClass bObject) {
C_Class cObject = bObject.someMethodThatReturnsC();
if(cObject != null) {
method2();
method2();
}
}}
Below is the TestClass:
public class AClassTest {
#InjectMocks
AClass AClassSpy;
#Mock
BClass b_objectMock;
#Mock
C_Class c_objectMock;
#BeforeMethod
public void beforeMethod() {
AClassSpy = spy(new AClass());
MockitoAnnotations.initMocks(this);
}
public void method1Test () {
doReturn(c_objectMock).when(b_objectMock).someMethodThatReturnsC());
AClassSpy.method1(b_objectMock);
verify(AClassSpy, times(2).method2();
}
}
However, it always FAILS, since the c_objectMock is always null. What do I do to tell Mockito to not to return a null object?

It works good, just use #Before annotation from junit, not #BeforeMethod, and mark your test method like #Test and remove second bracket from
doReturn(c_objectMock).when(b_objectMock).someMethodThatReturnsC())<-this one;
and add bracket at verify:
verify(AClassSpy, times(2)<-here.method2();
And just take care of your code!
This should work:
public class AClassTest {
#InjectMocks
private AClass AClassSpy;
#Mock
private BClass b_objectMock;
#Mock
private C_Class c_objectMock;
#Before
public void beforeMethod() {
AClassSpy = spy(new AClass());
MockitoAnnotations.initMocks(this);
}
#Test
public void method1Test() {
doReturn(c_objectMock).when(b_objectMock).someMethodThatReturnsC();
AClassSpy.method1(b_objectMock);
verify(AClassSpy, times(2)).method2();
}
}
Instead of before method you can use annotation #RunWith. It looks clearly:
#RunWith(MockitoJUnitRunner.class)
public class AClassTest {
#Spy
#InjectMocks
private AClass AClassSpy;
#Mock
private BClass b_objectMock;
#Mock
private C_Class c_objectMock;
#Test
public void method1Test() {
doReturn(c_objectMock).when(b_objectMock).someMethodThatReturnsC();
AClassSpy.method1(b_objectMock);
verify(AClassSpy, times(2)).method2();
}
}

You are having this behaviour because you are not mocking property the call to someMethodThatReturnsC.
It should be:
doReturn(c_objectMock).when(b_objectMock).someMethodThatReturnsC();