Consider the following sample code:
#Stateless
public class MyBean {
private SomeHelper helper;
private long someField;
#PostConstruct
void init() {
helper = new SomeHelper();
someField = initSomeField();
}
long initSomeField() {
// perform initialization
}
public void methodToTest() {
helper.someMethod();
long tmp = 3 + someField;
}
}
And here is the test template, that I always use
public class MyBeanTest {
#Spy
#InjectMocks
private MyBean testSubject;
#Mock
private SomeHelper mockedHelper;
#Before
public void before() {
MockitoAnnotations.initMocks(this);
doReturn(1L).when(testSubject).initSomeField();
}
#Test
public void test() {
testSubject.methodToTest();
// assertions
}
}
The problem with testing methodToTest is that it needs field someField to be initialized. But the initialization is done in #PostConstruct method. And I can't run this method before call to testSubject.methodToTest(), because it will re-initialize helper. Also, I don't want to manually set up all the mocks. And I don't want to use reflection to set the someField, because that would make MyBeanTest vulnerable to MyBean refactoring. Can anybody propose, maybe better design to avoid situations like this?
A few notes:
Logic in initSomeField could be quite heavy (including calls to database), so I want to initialize it only once in a #PostConstruct method.
I don't want to create a setter for this field or widen its access modifier, because that would allow unwanted changes to my field.
If your test is in the same package as your class, then you can just call initSomeField directly, since it's package private. You can either do this in each individual test method, or in your #Before method, provided it runs after initMocks.
Related
In my javaee project there is an interface:
public interface SomeInterface{...}
and multiple implementations:
#Stateless(name = "ImplementationA")
public class ImplementationA implements SomeInterface{...}
#Stateless(name = "ImplementationB")
public class ImplementationB implements SomeInterface{...}
In order to access all of the implementations, I have the following in an other class:
#Singelton
public class AnotherClass{
#Inject
#Any
private Instance<SomeInterface> impls;
public SomeInterface someMethod(){
for(SomeInterface imp : impls){
if(imp.oneMethod()){
return imp;
}
}
return null;
}
}
If I want to do unit test for this "AnotherClass", how do I mock the
Instance<SomeInterface> impls
field?
Tried #Mock, #Spy, could not get "impls" properly mocked from within Mockito, when the test runs, the "impls" is always null.
The Unit test itself looks like the following:
#RunWith(MockitoJUnitRunner.class)
public class SomeTestClass {
#InjectMocks
AnotherClass anotherClass;
#Spy // Here I tried #Mock as well
private Instance<SomeInterface> impls;
#Test
public void TestSomeMethod(){
Assert.assertTrue( anotherClass.someMethod() == null ); // <- NullPointerException here, which indicates the impls is null instead of anotherClass.
}
}
Had to add another method in that "AnotherClass" to accept an instance of Instance impls, which is created in unit test, which works but is ugly that another irrelevant method has to be added only for the purpose of unit test.
Any idea what the proper way of doing unit test looks like?
Mockito and Junit version:
group: 'junit', name: 'junit', version: '4.12'
group: 'org.mockito', name: 'mockito-core', version:'2.12.0'
Thanks in advance.
What you could try to do:
Add some expectations if you need them. You probably need this impls.xxxx() to call a real method if it is a Spy (guess this is default behavior).
Maybe also try to init mocks first:
#RunWith(MockitoJUnitRunner.class)
public class SomeTestClass {
#InjectMocks
AnotherClass anotherClass;
#Spy
private Instance<SomeInterface> impls;
// init here
#Before
public void initMocks() {
MockitoAnnotations.initMocks(this);
}
#Test
public void TestSomeMethod(){
anotherClass.someMethod(); // <- NullPointerException here, which indicates the impls is null instead of anotherClass.
}
}
This init call needs to be somewhere in the base class or a test runner.
That's weird it does not work without, I guess if you use MockitoJUnitRunner it should work.
UPD:
It's been a long time but I can see there are some new comments so providing additional input.
This is the test that works.
// ImplementationA.oneMethod simply returns TRUE in my case
// ImplementationB.oneMethod simply returns FALSE
#RunWith(MockitoJUnitRunner.class)
public class AnotherClassTest {
#Spy // can be Mock
Instance<SomeInterface> impls;
#InjectMocks
AnotherClass classUnderTest;
#Mock
Iterator<SomeInterface> iterator; // why need it - check below :)
#Test
public void someMethod() {
when(impls.iterator()).thenReturn(iterator);
when(iterator.hasNext()).thenReturn(true).thenReturn(false);
when(iterator.next()).thenReturn(new ImplementationA());
SomeInterface res = classUnderTest.someMethod();
System.out.println("done");
}
}
Where was the problem ? Here:
public SomeInterface someMethod() {
// explanation: For-Each uses iterator
// if we do not mock Instance<SomeInterface> impls properly
// impls.iterator() under the hood will return NULL -> NPE
for (SomeInterface imp : impls) {
if (imp.oneMethod()) {
return imp;
}
}
return null;
}
That is why in my test I also create dummy iterator (Mock). I also need to provide some expectations to make it work and here they are:
when(impls.iterator()).thenReturn(iterator); // returns my mock
when(iterator.hasNext()).thenReturn(true).thenReturn(false);
when(iterator.next()).thenReturn(new ImplementationA());
Hope it's clear :) Having this make the for-each works fine and returns ImplementationA.
Happy Hacking :)
I have a class under test whose constructer looks like this :
public class ClassUnderTest {
ClientOne clientOne;
ClientTwo clientTwo;
OtherDependency otherDependency;
#Inject
public ClassUnderTest(MyCheckedProvider<ClientOne> myCheckedProviderOne,
MyCheckedProvider<ClientTwo> myCheckedProviderTwo,
OtherDependency otherDependency) throws Exception {
this.clientOne = myCheckedProviderOne.get();
this.clientTwo = myCheckedProviderTwo.get();
this.otherDependency = otherDependency;
}
.
.
.
}
And the CheckedProvider looks thus :
public interface MyCheckedProvider<T> extends CheckedProvider<T> {
#Override
T get() throws Exception;
}
I could mock the clients, but how do I initialise the providers with my mocked clients.I use a combination of junit and mockito for writing tests.Any inputs would be appreciated.
What you could do is to mock providers rather than clients. ClientOne and ClientTwo are the types you are passing into your generic class, they are not variables and hence not something you want to mock. In contrast, the providers you are passing to the constructor are really variables, and what you need to control (simulate) are the behaviors of these variables.
public class ClassTest {
private static final CientOne CLIENT_ONE = new ClientOne();
private static final ClientTwo CLIENT_TWO = new ClientTwo();
#Mock
private MyCheckedProvider<ClientOne> providerOne;
#Mock
private MycheckedProvider<ClientTwo> providerTwo;
private ClassUnderTest classUnderTest;
#Before
public void setUp() {
when(providerOne.get()).thenReturn(CLIENT_ONE);
when(providerTwo.get()).thenReturn(CLIENT_TWO);
classUnderTest = new ClassUnderTest(providerOne, providerTwo, otherDependency);
}
}
As the other answer suggests, you could easily mock the providers, too.
But youMyCheckedProvider don't have to.
You already have an interface sitting there, so what would prevent you from creating something like
class MyCheckedProviderImpl<T> implements MyCheckedProvider<T> {
and that think takes a T object in its constructor and returns exactly that?
That is more or less the same what the mocking framework would be doing.
I am using Mockito to write a simple unit test.
Then, a function under test:
public class MyService {
public void getData() {
executor.execute(new MyRunnable() {
#Override
doTask() {
MyRestClient client = getRestClient();
Response resp = client.getFromServer();
persist(resp.getData());
}
});
}
}
protected MyRestClient getRestClient() {
return new MyRestClient();
}
My test case, I want to test doTask() has run & resp.getData() is persisted:
#Test
public void testGetData() {
MyService spyService = spy(MyService.getInstance());
// mock client
MyRestClient mockedClient = mock(MyRestClient.class);
mockedClient.setData("testData");
// stub getRestClient() function to return mocked client
when(spyService.getRestClient()).thenReturn(mockedClient);
// SUT
spyService.getData();
// run the Runnable task.
Mockito.doAnswer(new Answer<Object>() {
public Object answer(InvocationOnMock invocation) throws Exception {
Object[] args = invocation.getArguments();
Runnable runnable = (Runnable) args[0];
runnable.doTask();
return null;
}
}).when(executor).execute(Mockito.any(Runnable.class));
...
}
As you see above, I stub the getRestClient() function to return a mocked MyRestClient. However when run the test case, it doesn't stub the getRestClient() but run the real function. Why?
[Edit] following comment and review feedback
A rule of thumb is not to mock the class under test. Also your testing will be much easier if your class under test does not use the new keyword. Instead use Factory classes to create objects. There will be no need to use Mockito.spy() only Mockito.mock().
The fact that the following answer requires significant test setup is telling you that MyService has too much reposibility and needs to be simplified. However for the sake of answering your question directly here is how you can refactor your code to support verifying the call to persist() using Mocks.
MyService accepts in the constructor the objects that you will be mocking in your test setup. Having them passed into the constructor allows your JUnit test case to create the Mocks and keep a reference to them for verification later.
public class MyService {
private MyRunnableFactory runFactory;
private MyRestClientFactory restFactory;
private MyRestDao dao;
// inject constructor arguments
public MyService(MyRunnableFactory runFactory, MyRestClientFactory restFactory, MyRestDao dao) {
this.runFactory = runFactory;
this.restFactory = restFactory;
this.dao = dao;
}
public void getData() {
MyRestClient restClient = restFactory.createInstance();
MyRunnable runner = runFactory.createInstance(restClient, dao);
executor.execute(runner);
}
}
MyRunnable is created so that it can be tested in isolation if required. Again we inject the Mock objects into the constructor. It is tempting to inline Runnables as you have written in your question, however you lose the ability to control the new instance being created within you tests.
public class MyRunnable implements Runnable {
private MyRestClient restClient;
private MyRestDao dao;
public MyRunnable(MyRestClient restClient, MyRestDao dao) {
this.restClient = restClient;
this.dao = dao;
}
public void run() {
Response resp = restClient.getFromServer();
dao.persist(resp.getData());
}
}
MyRestDao is created because this is the class that you want to Verify in your test case. I don't see where persist() is defined in your question so we create a Data Access Object (DAO) to implement it.
public class MyRestDao {
public void persist() {
// save to some repository
}
}
Now let's write the test case that uses the above classes. We want to verify that the persist() method has been called
#RunWith(MockitoJUnitRunner.class)
public class MyServiceTest {
#Mock MyRestDao dao;
#Mock MyRestClient restClient;
#Mock MyRunnableFactory runFactory;
#Mock MyRestClientFactory restFactory;
#Test
public void testPersistIsCalled() {
Response expectedResponse = new Response("some data"); // real implementation, not mocked
MyRunnable runner = new MyRunnable(restClient, dao); // real implementation, not mocked
when(restFactory.createInstance()).thenReturn(restClient);
when(runFactory.createInstance(restClient, dao)).thenReturn(runner);
when(restClient.getFromServer()).thenReturn(expectedResponse);
when(restClient.getData()).thenReturn(myRunnable);
// method under test
MyService service = new MyService(runFactory, restFactory);
service.getData();
verify(dao).persist(expectedResponse.getData());
}
}
Note that this test case is brittle because it is tightly coupled to the actual implementation of the MyService class. Ideally you want tests that don't need to know about the internal workings of your class under test.
I am using PowerMockito and jUnit to write unit test cases.
public class Foo {
private String resolveApplicationId() {
return "testApplication";
}
}
Here is my test case
#RunWith(PowerMockRunner.class)
#PrepareForTest(Foo.class)
public class test{
#Before
public void prepareTest() {
foo = PowerMockito.spy(new Foo());
}
#Test
public void checkApplicationIdIsResolved() throws Exception {
PowerMockito.doNothing().when(foo, "myPrivateMethod");
PowerMockito.verifyPrivate(foo).invoke("myPrivateMethod");
//Assert Here the returned value
}
}
Please tell me
1. how can I assert the value returned by the method when it is called
2. how can I call the private method
3. if not then what actually I verify when I write test case for private methods.
Thanks.
Testing private method does not differ from testing public method. If there is no external dependencies you even don't need to create and use any mocks. The only problem is with invocation of the private method from test. This is described here or you may use spring utils.
So you don't need to mock the method you are testing. You only require to mock other objects which are not tested in this particular test. So you test would look like
#Test
public void checkApplicationIdIsResolved() throws Exception {
// makeResolveIdAccessible();
// if needed setup mocks for objects used in resolveApplicationId
assertEquals(expectedApplicationId, foo.resolveApplicationId())
}
I am using PowerMock to mock static methods in junit tests, typically done as follows:
#RunWith(PowerMockRunner.class)
#PrepareForTest({Foo.class,Bar.class})
public class SomeUnitTest {
#Before
public void setUpTest() {
setUpFoo();
setUpBar();
}
private void setUpFoo() {
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private void setUpBar() {
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
#Test
public void someTestCase() {
...
}
}
This works fine, but I'm finding that specifying the #PrepareForTest annotation is preventing me from making my testing API flexible.
What I'd like to do is something like the following:
public class MockLibraryOne {
public static void setUpLibraryOne() {
setUpFoo();
setUpBar();
}
private static void setUpFoo() {
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private static void setUpBar() {
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
}
#RunWith(PowerMockRunner.class)
public class SomeUnitTest {
#Before
public void setUpTest() {
MockLibraryOne.setUpLibraryOne();
}
#Test
public void someTestCase() {
...
}
}
Here my unit test has a dependency on LibraryOne, but it does not know which classes LibraryOne depends on, so it does not know which classes to add to the #PrepareForTest annotation.
I could make SomeUnitTest extend MockLibraryOne and add the #PrepareForTest annotation to the MockLibraryOne class, but I will have dependencies on more than just MockLibraryOne in other unit tests, so inheritance is not a general solution.
Is there some way of programmatically preparing a class for testing under PowerMock, instead of using the #PrepareForTest annotation? For example, something like the following:
public class MockLibraryOne {
public static void setUpLibraryOne() {
setUpFoo();
setUpBar();
}
private static void setUpFoo() {
prepareForTest(Foo.class);
mockStatic(Foo.class);
when(Foo.someStaticMethod()).thenReturn(1);
}
private static void setUpBar() {
prepareForTest(Bar.class);
mockStatic(Bar.class);
when(Bar.someStaticMethod()).thenReturn(2);
}
}
I guess it would be nice if PowerMockRunner processed the #PrepareForTest annotation a little differently: for each specified class, it should not only add that class (and its hierarchy) to the list of classes to prepare for mocking, but then examine that class to see if it has any #PrepareForTest annotations as well:
#RunWith(PowerMockRunner.class)
#PrepareForTest({MockLibraryOne.class})
public class SomeUnitTest {
...
}
#PrepareForTest({Foo.class,Bar.class})
public class MockLibraryOne {
...
}
}
So in this the #PrepareForTest annotation on SomeUnitTest would find MockLibraryOne, and the #PrepareForTest annotation there would drag in Foo.class and Bar.class as well.
So perhaps writing my own test runner to replace PowerMockRunner may be a solution.
Or perhaps there's a simpler solution, using PowerMockAgent class, for example?
edit: Mock Policies may be one solution: https://code.google.com/p/powermock/wiki/MockPolicies
edit: Mock Policies works with PowerMockRunner but not (it seems) with PowerMockRule (which I sometimes require due to class loader issues).
What you try to achieve will not work.
The problem is that powermock must rewrite the client class's code to intercept the static invocation and it can't do this after the class is loaded. Thus it can only prepare a class for test before it is loaded.
Let's assume you want to mock the System.currentTimeMillis invocation in the following simple class.
class SystemClock {
public long getTime() {
return System.currentTimeMillis();
}
}
Powermock will not change the code of java.lang.System.currentTimeMillis, because it can't. Instead it changes the SystemClock's byte code so that it does not invoke System.currentTimeMillis anymore. Instead it invokes some other object that belong to powermock.
This is how powermock get's full control over the return value and allows you to write a test like this:
#RunWith(PowerMockRunner.class)
#PrepareForTest({ SystemClock.class })
public class PowerMockitoTest {
#Test
public void systemTimeMillis() {
SystemClock systemClock = new SystemClock();
PowerMockito.mockStatic(System.class);
PowerMockito.when(System.currentTimeMillis()).thenReturn(12345L);
long time = systemClock.getTime();
assertEquals(12345L, time);
}
}
You can see that powermock has rewritten the client class in the stacktrace of your debugger. Set a breakpoint at SystemClock.getTime and step into the invoked method.
As you can see SystemClock invokes a MockGateway.
If you take a look at the variables on the stack of the MockGateway invocation, you can see how the original System.currentTimeMillis method is handled.
Perhaps you're looking for a mock policy?
Could you help this (taken from documentation)?
You can also prepare whole packages for test by using wildcards:
#PrepareForTest(fullyQualifiedNames="com.mypackage.*")
So you can add the whole library to your prepare...
Why do you even want to mock static methods? Why not wrap those static methods in a class that you can mock with mockito?
class FooWraper {
void someMethod() {
Foo.someStaticMethod()
}
}
and then you can create a mock of your FooWraper. No need to use Powermock at all...