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SpringBoot Mockito: when..thenReturn giving an exception

So, currently, I'm testing on a Service class
This is my ConvertService.java
#Service
public class ConvertService {
private final NetworkClient networkClient; //NetworkClient is a Service too
private final ConvertUtility convertUtility;
public ConvertService(Network networkClient) {
convertUtility = ConvertFactory.of("dev", "F");
this.networkClient = networkClient
}
public Response convert(Request request) {
User user = networkClient.getData(request.getId()); //User is POJO class
Context context = convertUtility.transform(request.getToken()) //getToken returns a String
//Context is a normal Java
}
}
This is my ConvertServiceTest.java
#SpringBootTest
#RunWith(MockitoJunitRunner.class)
class ConvertServiceTest {
#MockBean
private NetworkClient networkClient;
#Mock
ConvertUtility convertUtility;
private ConvertService convertService;
#BeforeEach
void setUp() {
convertService = new ConvertService(networkClient);
}
private mockMethod() {
Request request = Request(1000);
User user = new User("user1");
Context context = new Context();
when(networkClient.getData(anyLong())).thenReturn(user);
when(convertUtility.transform(any(String.class)).thenReturn(context);
Response response = convertService.convert(request); //it throws me an exception here
}
}
convertService.convert(request); throws an exception
pointing inside convertUtility.transform(request.getToken())
I'm not sure why it's processing everything from transform method, when I wrote
when(convertUtility.transform(any(String.class)).thenReturn(context);
Can anyone please help?
EDIT: ConvertUtility is a read-only library

Inside your public constructor, you're using a static factory method to get an instance of the ConvertUtility. You'd have to mock the static ConvertUtility.of() method to work with a mock during your test.
While Mockito is able to mock static methods, I'd recommend refactoring (if possible) your class design and accepting an instance of ConvertUtility as part of the public constructor:
#Service
public class ConvertService {
private final NetworkClient networkClient; //NetworkClient is a Service too
private final ConvertUtility convertUtility;
public ConvertService(Network networkClient, ConvertUtility convertUtility) {
this.convertUtility = convertUtility
this.networkClient = networkClient
}
}
With this change, you can easily mock the collaborators of your ConvertService when writing unit tests:
#ExtendWith(MockitoExtension.class)
class ConvertServiceTest {
#Mock
private NetworkClient networkClient;
#Mock
private ConvertUtility convertUtility;
#InjectMocks
private ConvertService convertService;
#Test // make sure it's from org.junit.jupiter.api
void yourTest() {
}
}

Mock method return type in java

Below is main code consist of one util class and service class using it
#PropertySource("classpath:atlas-application.properties")
public class ApacheAtlasUtils {
#Value("${atlas.rest.address}")
private String atlasURL;
#Value("${atlas.rest.user}")
private String atlasUsername;
#Value("${atlas.rest.password}")
private String atlasPassword;
private AtlasClientV2 client;
public AtlasClientV2 createClient() {
if (client == null) {
return new AtlasClientV2(new String[] {atlasURL}, new String[] {atlasUsername, atlasPassword});
} else {
return client;
}
}
}
Service Class is below :-
#Override
public Page<SearchResultDto> findFilesWithPages(QueryParent queryParent, Pageable pageable)
throws AtlasServiceException {
// Some code
client = new ApacheAtlasUtils().createClient();
//some code
}
I am writing unit test for service method and I am getting exception for createClient method asking for values for url, username and password which should not happen as this should be mocked but the mocking is giving me below error
java.lang.IllegalArgumentException: Base URL cannot be null or empty.
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:141)
at org.apache.atlas.AtlasServerEnsemble.<init>(AtlasServerEnsemble.java:35)
at org.apache.atlas.AtlasBaseClient.determineActiveServiceURL(AtlasBaseClient.java:318)
at org.apache.atlas.AtlasBaseClient.initializeState(AtlasBaseClient.java:460)
at org.apache.atlas.AtlasBaseClient.initializeState(AtlasBaseClient.java:448)
at org.apache.atlas.AtlasBaseClient.<init>(AtlasBaseClient.java:132)
at org.apache.atlas.AtlasClientV2.<init>(AtlasClientV2.java:82)
at com.jlr.stratus.commons.utils.ApacheAtlasUtils.createClient(ApacheAtlasUtils.java:40)
at com.jlr.stratus.rest.service.impl.FileSearchService.findFilesWithPages(FileSearchService.java:49)
The Test code is as follows:-
private FileSearchService fileSearchService;
#Spy
private ApacheAtlasUtils apacheAtlasUtils;
#Mock
private AtlasClientV2 client;
#Before
public void setup() {
MockitoAnnotations.initMocks(this);
fileSearchService = new FileSearchService();
}
#Test
public void findFilesWithPages_searchAll() throws AtlasServiceException {
Mockito.doReturn(client).when(apacheAtlasUtils).createClient();
service.search(queryParent,pageable);
}

Your idea with spying is adequate (you can even go for mocking if you do not actually need any true implementation of that class).
The problem lies in the implementation:
// Some code
client = new ApacheAtlasUtils().createClient();
//some code
}
Instead of having the ApacheAtlasUtils as an instance variable (or a supplier method) you create the instance on the fly.
Mockito is not smart enough to catch that operation and replace the real object with you spy.
With the supplier method you can set up your test as follows:
#Spy
private FileSearchService fileSearchService = new FileSearchService();
#Spy
private ApacheAtlasUtils apacheAtlasUtils = new ApacheAtlasUtils();
#Mock
private AtlasClientV2 client;
#Before
public void setup() {
MockitoAnnotations.initMocks(this);
doReturn(apacheAtlasUtils).when(fileSearchService).getApacheUtils();
}
in your SUT:
#Override
public Page<SearchResultDto> findFilesWithPages(QueryParent queryParent, Pageable pageable)
throws AtlasServiceException {
// Some code
client = getApacheUtils().createClient();
//some code
}
ApacheAtlasUtils getApacheUtils(){
return new ApacheAtlasUtils();
}

Unit test singleton class method in android using PowerMock

I need to do unit testing of methods of Singleton class which internally uses RxJava Singles, and used PowerMock test framework to mock static class and methods. I tried various method to mock Schedulers.io() and AndroidSchedulers.mainThread() methods but it's not working. I'm getting java.lang.NullPointerException error at line .subscribeOn(Schedulers.io()) inside UserApi.verifyUserData() method.
Singleton Class UserApi (Class under Test)
final public class UserApi {
private CompositeDisposable compositeDisposable;
private String userID;
//private final SchedulerProvider schedulerProvider;
private UserApi(String userId) {
super();
this.userID = userId;
//this.schedulerProvider = schedulerProvider;
}
public static UserApi getInstance() {
return SingletonHolder.sINSTANCE;
}
private static final class SingletonHolder {
private static final UserApi sINSTANCE;
static {
String uuid = UUID.randomUUID().toString();
sINSTANCE = new UserApi(uuid);
}
}
// Rest Api call
public void verifyUserData(byte[] doc, byte[] img) {
this.compositeDisposable = new CompositeDisposable();
String docStr = Base64.encodeToString(doc, Base64.NO_WRAP);
String imgStr = Base64.encodeToString(img, Base64.NO_WRAP);
final Disposable apiDisposable = IdvManager.getInstance().getUserManager().verifyUserData(docStr, imgStr)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<JsonObject>() {
#Override
public void accept(JsonObject verifyResponse) throws Exception {
pollResult();
}
}, new Consumer<Throwable>() {
#Override
public void accept(Throwable error) throws Exception {
// handle error code...
}
});
this.compositeDisposable.add(apiDisposable);
}
private void pollResult() {
// code here...
}
}
UserManager Class and Interface
public interface UserManager {
Single<JsonObject> verifyUserData(String docStr, String imgStr);
}
final class UserManagerImpl implements UserManager {
private final UserService userService;
UserManagerImpl(final Retrofit retrofit) {
super();
this.userService = retrofit.create(UserService.class);
}
#Override
public Single<JsonObject> verifyUserData(String docStr, String imgStr) {
// Code here...
}
}
Unit Test
#RunWith(PowerMockRunner.class)
#PrepareForTest({IdvManager.class, Base64.class, Schedulers.class, AndroidSchedulers.class, UserApi.class})
public class UserApiTest {
#Mock
public UserManager userManager;
#Mock
private Handler handler;
private IdvManager idvManager;
private Schedulers schedulers;
private UserApi spyUserApi;
private TestScheduler testScheduler;
private String userID;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
testScheduler = new TestScheduler();
handler = new Handler();
PowerMockito.suppress(constructor(IdvManager.class));
// mock static
PowerMockito.mockStatic(IdvManager.class);
PowerMockito.mockStatic(Schedulers.class);
PowerMockito.mockStatic(AndroidSchedulers.class);
PowerMockito.mockStatic(Base64.class);
// Create mock for class
idvManager = PowerMockito.mock(IdvManager.class);
schedulers = PowerMockito.mock(Schedulers.class);
PowerMockito.when(IdvManager.getInstance()).thenReturn(IdvManager);
when(idvManager.getUserManager()).thenReturn(userManager);
spyUserApi = PowerMockito.spy(UserApi.getInstance());
// TestSchedulerProvider testSchedulerProvider = new TestSchedulerProvider(testScheduler);
when(Base64.encodeToString((byte[]) any(), anyInt())).thenAnswer(new Answer<Object>() {
#Override
public Object answer(InvocationOnMock invocation) throws Throwable {
return java.util.Base64.getEncoder().encodeToString((byte[]) invocation.getArguments()[0]);
}
});
when(schedulers.io()).thenReturn(testScheduler);
when(AndroidSchedulers.mainThread()).thenReturn(testScheduler);
userID = UUID.randomUUID().toString();
}
#After
public void clearMocks() {
//Mockito.framework().clearInlineMocks();
}
#Test
public void verifyUserData_callsPollResult_returnsResponse() {
// Input
String docStr = "iVBORw0KGgoAAAANSUhEUgAAAJ4AAACeCAYAAADDhbN7AA.....";
// Output
JsonObject verifyResponse = new JsonObject();
verifyResponse.addProperty("status", "Response created");
doReturn(Single.just(verifyResponse)).when(userManager).verifyUserData(docStr, docStr);
// spy method call
spyUserApi.verifyUserData(docFrontArr, docFrontArr);
testScheduler.triggerActions();
// assert
verify(userManager).verifyUserData(docStr, docStr);
}
}
Error
java.lang.NullPointerException
at com.rahul.manager.UserApi.verifyUserData(UserApi.java:60)
at com.rahul.manager.UserApiTest.verifyUserData_callsPollResult_returnsResponse(UserApiTest.java:171)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
I'm not sure whether i can test methods of Singleton class by spying on real instance of Singleton class using PowerMock.

Testing your code is complex because it's not testable and it's not extensible. It contains hardcoded dependencies everywhere (e.g. user id, handler, several singletons).
If you decide to use another id generation approach or another handler, you won't be able to do this without rewriting whole class.
Instead of hardcoding dependencies, ask for them in constructor (for mandatory dependencies) or setters (for optional ones).
This will make your code extensible and testable. After you do this, you will see your class contains several responsibilities, after moving them into separate classes, you will get much better picture :-)
For example:
public UserApi(String userId, Handler handle) {
this.userId = userId;
this.handler = handler;
}

Schedulers.io() is a static method, so you need to use mockStatic (which you did) and define the related mock accordingly.
I rearranged your setup method a bit, to improve the readability and fixed the mistake. You do not need an instance of Schedulers (The variable you named schedulers).
Probably a simple typo you made, as you did the right thing for Base64 and AndroidSchedulers.
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
testScheduler = new TestScheduler();
handler = new Handler();
// mock for instance of `IdvManager`
PowerMockito.suppress(constructor(IdvManager.class));
idvManager = PowerMockito.mock(IdvManager.class);
when(idvManager.getUserManager()).thenReturn(userManager);
// mock for `IdvManager` class
PowerMockito.mockStatic(IdvManager.class);
PowerMockito.when(IdvManager.getInstance()).thenReturn(idvManager);
// mock for `Schedulers` class
PowerMockito.mockStatic(Schedulers.class);
when(Schedulers.io()).thenReturn(testScheduler);
// spy for instance of `UserApi`
spyUserApi = PowerMockito.spy(UserApi.getInstance());
// mock for `Base64` class
PowerMockito.mockStatic(Base64.class);
when(Base64.encodeToString((byte[]) any(), anyInt())).thenAnswer(new Answer<Object>() {
#Override
public Object answer(InvocationOnMock invocation) throws Throwable {
return java.util.Base64.getEncoder().encodeToString((byte[]) invocation.getArguments()[0]);
}
});
// mock for `AndroidSchedulers` class
PowerMockito.mockStatic(AndroidSchedulers.class);
when(AndroidSchedulers.mainThread()).thenReturn(testScheduler);
userID = UUID.randomUUID().toString();
}
However the NPE is missing the part that actually indicates its failing from this, consider adding it if that does not solve your problem.

junit - how to mock field in real class?

I have a tricky situation. I am using MVP architecture for android but thats not important. I have a class called DoStandardLoginUsecase that basically just connects to a server with login info and gets a access token. i am trying to test it. But the problem is the context that i am passing in to it so i can initialize dagger.
public class DoStandardLoginUsecase extends BaseUseCase {
#Inject
UserDataRepository mUserDataRepo;
private StandardLoginInfo loginInfo;
public DoStandardLoginUsecase(Context context) {
/* SEE HERE I AM USING A APPLICATION CONTEXT THAT I PASS TO DAGGER
*/
((MyApplication)context).getPresenterComponent().inject(this);
}
#Override
public Observable<Login> buildUseCaseObservable() {
return mUserDataRepo.doStandardLogin(loginInfo);
}
public void setLoginInfo(StandardLoginInfo loginInfo) {
this.loginInfo = loginInfo;
}
}
and here is the test i have so far:
public class DoStandardLoginUsecaseTest {
DoStandardLoginUsecase standardLoginUsecase;
StandardLoginInfo fakeLoginInfo;
TestObserver<Login> subscriber;
MockContext context;
#Before
public void setUp() throws Exception {
//now when i create the object since its a mock context it will fail when it tries to call real things as these are stubs. So how do i test this object. how do i create an instance of this object ? I am willing to use [daggerMock][1] if that helps also.
standardLoginUsecase = New DoStandardLoginUsecase(context);
fakeLoginInfo = new StandardLoginInfo("fred#hotmail.com","Asdfgh4534");
subscriber = TestObserver.create();
}
#Test
public void buildUseCaseObservable(){
standardLoginUsecase.seLoginInfo(fakeLoginInfo);
standardLoginUsecase.buildUseCaseObservable().subscribe(subscriber);
subscriber.assertNoErrors();
subscriber.assertSubscribed();
subscriber.assertComplete();
}
}

I would do the test like this:
public class DoStandardLoginUsecaseTest {
private DoStandardLoginUsecase target;
private MyApplication contextMock;
#Before
public void beforeEach() {
contextMock = Mockito.mock(MyApplication.class);
// Note that you need to mock the getPresenterComponent
// but I don't know what it returns.
target = new DoStandardLoginUsecase(contextMock);
}
#Test
public void buildUseCaseObservable() {
UserDataRepository userDataMock = Mockito.mock(UserDataRepository.class);
StandardLoginInfo loginInfoMock = Mockito.mock(StandardLoginInfo.class);
target.mUserDataRepo = userDataMock;
target.setLoginInfo(loginInfoMock);
Observable<Login> expected = // create your expected test data however you like...
Mockito.when(userDataMock.doStandardLogin(loginInfoMock)).thenReturn(expected);
Observable<Login> actual = target.buildUseCaseObservable();
Assert.areSame(actual, expected);
}
}

How can I a get singleton from Guice that's configured with runtime parameters?

My overall goal is to load properties from a properties file and then inject those properties into my objects. I would also like to use those properties to instantiate certain singleton classes using Guice. My singleton class looks like this:
public class MainStore(){
private String hostname;
#Inject
public void setHostname(#Named("hostname") String hostname){
this.hostname = hostname;
}
public MainStore(){
System.out.println(hostname);
}
}
I'm trying to instantiate a singleton using this provider:
public class MainStoreProvider implements Provider<MainStore> {
#Override
public MainStore get(){
MainStore mainStore = new MainStore();
return mainStore;
}
}
My configurationModule is a module that loads a configuration from a property file specified at runtime:
public class ConfigurationModule extends AbstractModule {
#Override
protected void configure(){
Properties properties = loadProperties();
Names.bindProperties(binder(), properties);
}
private static Properties loadProperties() {
String resourceFileName = "example.properties";
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream inputStream = classLoader.getResourceAsStream(resourceFileName);
Properties properties = new Properties();
properties.load(inputStream);
return properties;
}
}
And my example.properties files contains:
hostname = testHostName
Then when I need the MainStore singleton I'm using:
Injector injector = Guice.createInjector(new ConfigurationModule());
MainStoreProvider mainStoreProvider = injector.getInstance(MainStoreProvider.class);
MainStore mainStore = mainStoreProvider.get(); //MainClass singleton
Is this the right path to go down? Should I be doing this a completely different way? Why does my MainStore not print out the correct hostname?

I have written up a small example that demonstrates how to bind a Singleton, how to inject a property and so on.
public class TestModule extends AbstractModule {
#Override
protected void configure() {
Properties p = new Properties();
p.setProperty("my.test.string", "Some String"); // works with boolean, int, double ....
Names.bindProperties(binder(),p);
bind(X.class).to(Test.class).in(Singleton.class); // This is now a guice managed singleton
}
public interface X {
}
public static class Test implements X {
private String test;
#Inject
public Test(#Named("my.test.string") String test) {
this.test = test;
System.out.println(this.test);
}
public String getTest() {
return test;
}
}
public static void main(String[] args) {
Injector createInjector = Guice.createInjector(new TestModule());
Test instance = createInjector.getInstance(Test.class);
}
}
The configure method is now responsible to tell guice that my Test class is a singleton.
It prints the correct hostname (property test) because I inject the constructor and set the property.
You can do this with a provider as well, however you will then have to create your objects manually. In my case, this would look like this:
public static class TestProvider implements Provider<X> {
private String test;
private X instance;
public TestProvider(#Named("my.test.string") String test) {
this.test = test;
}
#Override
public X get() {
if(instance == null) {
instance = new Test(test);
}
return instance;
}
}
Binding will then look like this:
bind(X.class).toProvider(TestProvider.class);
Is this what you wanted?
Cheers,
Artur
Edit:
I did some test and found this to note:
You can bind a provider as a singleton:
bind(X.class).toProvider(TestProvider.class).in(Singleton.class);
That way you do not need to handle singleton creation yourself:
public static class TestProvider implements Provider<X> {
private String test;
private X instance;
#Inject
public TestProvider(#Named("my.test.string") String test) {
this.test = test;
}
#Override
public X get() {
return instance;
}
}
The above code will create singletons of the object X.