I am using Mockito to mock a method in the same class for which I am writing test. I have seen other answers on SO (Mocking method in the same class), but probably I am misunderstanding them, since I running into issues.
class Temp() {
public boolean methodA(String param) {
try {
if(methodB(param))
return true;
return false;
} catch (Exception e) {
e.printStackTrace();
}
}
}
My Test method:
#Test
public void testMethodA() {
Temp temp = new Temp();
Temp spyTemp = Mockito.spy(temp);
Mockito.doReturn(true).when(spyTemp).methodB(Mockito.any());
boolean status = temp.methodA("XYZ");
Assert.assertEquals(true, status);
}
I however get the expection printed out because definition of methodB gets executed.
My understanding is definition of methodB would get mocked by using spyTemp. However that does not appear to be the case.
Can someone please explain where I am going wrong?
The first issue is that you have to use spyTemp object to expect something from Mockito. Here it is not the same as test. spyTemp is wrapped by the Mockito object temp.
Another issue is that you stub only methodB(), but you are trying to run methodA(). Yes in your implementation of methodA() you call methodB(), but you call this.methodB(), not spyTemp.methodB().
Here you have to understand that mocking would work only when you call it on the instance of temp. It's wrapped by a Mockito proxy which catches your call, and if you have overriden some method, it will call your new implementation instead of the original one. But since the original method is called, inside it you know nothing about Mockito proxy. So your "overriden" method would be called only when you run spyTemp.methodB()
This should work:
Mockito.doReturn(true).when(spyTemp).methodB(Mockito.any());
boolean status = spyTemp.methodA("XYZ");
You created a spy and mocked methodB(). That is correct! But you called methodA() on the original object. To get the correct result call it on the spy
boolean status = spyTemp.methodA("XYZ");
Note the following from Mockito documentation:
Mockito does not delegate calls to the passed real instance, instead
it actually creates a copy of it. So if you keep the real instance and
interact with it, don't expect the spied to be aware of those
interaction and their effect on real instance state. The corollary is
that when an unstubbed method is called on the spy but not on the
real instance, you won't see any effects on the real instance.
This is referring specifically to your situation. You keep a reference to temp and then call its methodA. Mockito is not spying on that instance at all; it's spying on spyTemp. So the normal methodB is called.
Note that you should avoid partial mocks altogether for new code.
Related
I am trying to mock class instance and then return the mock object when we call the instance function but in result, it makes an actual call to function.
Here is my code:
AuthenticationSessionModel authSessionCookie =
new AuthenticationSessionManager(session)
.getCurrentAuthenticationSession(realm, client, tabId);
and my test code is:
AuthenticationSessionManager spyAuthSessionManager =
Mockito.spy(new AuthenticationSessionManager(session));
doReturn(authenticationSessionModel)
.when(spyAuthSessionManager)
.getCurrentAuthenticationSession(any(), any(), anyString());
It makes an actual call to getCurrentAuthenticationSession() and returns me Null Pointer Exception
In the test, you create a spy, and stub some behaviour.
But you don't use that spy in the code under test.
Instead, in the code under test you create a new AuthenticationSessionManager.
You need to restructure your code and:
create AuthenticationSessionManager outside of object under test.
pass it to object under test. Constructor is the first thing that comes to mind.
With these changes, it becomes trivial to substitute a real AuthenticationSessionManager with a spy in a test.
I have a class which contains the following three methods:
void add(Service... objs)
void add(Collection<Service> objs)
void add(Stream<Service> objs)
As you might expect, these all support the adding of zero or more objects, which can be specified individually or as part of an array, a collection or a stream. The first two variants create a stream from their arguments, and pass them to the third variant which actually does the adding.
In testing an object that uses this class, I have created a Mockito mock object to represent an instance of this class, using Spring's #MockBean annotation. I can see in the debugger that the object under test contains the mock object, and that the call I am expecting (with a single argument of type Service) is being addressed to the mock. Because the method that should be called is the first variant (the varargs one), and I know that varargs parameters are a little tricky, I coded the test to check that the mock is called with the correct parameter as follows:
ArgumentCaptor<Service> captor = ArgumentCaptor.forClass(Service.class);
verify(theMock).add(captor.capture());
assertThat(captor.getAllValues()).containsExactly(expectedService);
However, when I run this code the assertion fails because the List returned by captor.getAllValues() contains not a Service, but a Stream: the failure message says:
java.lang.AssertionError:
Expecting:
<[java.util.stream.ReferencePipeline$Head#2cfe272f]>
to contain exactly (and in same order):
<[com.xxx.data.Service#37c5]>
but some elements were not found:
<[com.xxx.data.Service#37c5]>
and others were not expected:
<[java.util.stream.ReferencePipeline$Head#2cfe272f]>
When I run the code in the debugger, I can see that the call from the object under test to add(Service...) invokes the real implementation; this invokes add(Stream<Service>) and it is that call which is intercepted by the mock. That explains why I am seeing the failure, but I don't understand why the mock is failing to intercept the original call, or what I can do to make it do so.
Update your ArgumentCaptor to accept Service[]
ArgumentCaptor<Service[]> serviceCaptor = ArgumentCaptor.forClass(Service[].class);
And assert
Service[] actualServices = serviceCaptor.getAllValues();
assertEquals(actualServices.length, 1);
assertEquals(actualServices[0], service);
And it's best practice to use ErrorCollector in Junit to assert more than one
assert and SoftAssect in Testng and call after your assertion softAssert.assertAll()
I have come up with a workaround to the problem, but the actual problem still exists and I think it is probably a Mockito bug (raised as https://github.com/mockito/mockito/issues/1929).
The workaround is to add this method to my test class. I've added a generic method because it is not just a call to the add() method that has the problem, but also a call to a similar overloaded remove() method that takes String arguments.
private <T, V> void verifyCall(T mock, BiConsumer<T, V> call,
V expectedArg, Class<V> type)
{
ArgumentCaptor<V> captor = ArgumentCaptor.forClass(type);
call.accept(verify(mock), captor.capture());
List<?> values = captor.getAllValues();
try {
assertThat(values.get(0)).isEqualTo(expectedArg);
} catch (AssertionFailedError ex) {
assertThat((Stream<V>) values.get(0)).containsExactly(expectedArg);
}
}
This should work whether the call intercepted by the mock was to the varargs variant of the method (as it should be) - in which case the assertion in the body of the try block will not throw an exception - or to the Stream variant (as it currently is) - in which case the assertion in the body will throw an exception and the assertion in the catch block will be executed.
Then, when I want to verify that my mock's add() method was called with the expected Service object, I do so with:
verifyCall(theMock, Datastore::add, expectedService, Service.class);
And similarly, for the remove() method:
verifyCall(theMock, Datastore::remove, expectedDeletedKey, String.class);
Very pleasingly, when I finally got this working the test failed because I had made a mistake in the method under test. Which made it all worthwhile.
D'oh. I failed to spot that the two varargs methods were declared as final. Removed this and it all works as expected.
How would I mock methods that accept a lambda using Mockito so that I am able to control which arguments are passed into the callback? I am specifically trying to mock the JDBI method useExtension which is used like this:
jdbi.useExtension(OrgUnitDao.class, dao -> {
// Skip if already loaded
// Skip if already loaded
if (dao.orgUnitsAreLoaded()) {
I would like to substitute the dao object passed back into the callback so that I could control the branching using the return value of dao.orgUnitsAreLoaded().
The signature looks like this
public <E,X extends Exception> void useExtension(Class<E> extensionType,
ExtensionConsumer<E,X> callback)
throws NoSuchExtensionException,
X extends Exception
This is the full answer to my question. It's simplified down to the very basics of how to do the stubbing and so doesn't reflect the production code I am to test, but it shows exactly the mechanics needed to do it.
final Jdbi jdbi = mock(Jdbi.class);
doAnswer(invocation -> {
System.out.println("this is the doAnswer lambda - just setting up the answer and the mocks");
final Class<OrgUnitDao> daoClass = invocation.getArgument(0);
final ExtensionConsumer callback = invocation.getArgument(1);
final OrgUnitDao mock1 = mock(daoClass);
when(mock1.orgUnitsAreLoaded()).thenReturn(false);
// call the actual callback method
callback.useExtension(mock1);
return null;
}).when(jdbi).useExtension(eq(OrgUnitDao.class), any());
// This is the method call I am to test
// Regard this as hidden away in some outer method in
// the System-Under-Test, but that I have been able
// to inject all its dependencies
jdbi.useExtension(OrgUnitDao.class, new Foo());
/// Further down, outside of the method
// Only replaced the lambda with this to get toString() for debugging ...
class Foo implements ExtensionConsumer<OrgUnitDao, RuntimeException> {
#Override
public void useExtension(OrgUnitDao orgUnitDao) throws RuntimeException {
System.out.println("A real method call, now using the passed in mocked dao:" + orgUnitDao.orgUnitsAreLoaded());
}
#Override
public String toString() {
return "OrgUnitDao class";
}
}
To parallel the conversation on the question "Calling callbacks with Mockito", your lambda might be called synchronously during the execution of your method-under-test, or it might be called later based on some external factor or interaction. Like Dawood's answer there, your answer here using a Mockito Answer will work, and is the only way to go if you are looking for the synchronous style (where mockJdbi calls your lambda immediately before methodUnderTest returns). If your lambdas are going to be called asynchronously, or if your system tolerates you calling the lambda asynchronously, you might want to test the state after your method-under-test returns but before you interact with the lambda.
// MockitoJUnitRunner, MockitoRule, or MockitoAnnotations.initMocks populate these.
// Especially useful for the ArgumentCaptor's generic arguments.
#Mock Jdbi mockJdbi;
#Mock OrgUnitDao mockOrgUnitDao;
#Captor ArgumentCaptor<ExtensionConsumer<OrgUnitDao, RuntimeException>>
extensionConsumerCaptor;
#Test public void yourTest() throws Exception {
// No stubbing needed! Just create the system under test.
YourSystemUnderTest systemUnderTest = new YourSystemUnderTest(mockJdbi);
// Call the method under test, which presumably calls useExtension(...).
systemUnderTest.methodUnderTest();
// Assert anything that should be true before the lambda is called.
assertFalse(systemUnderTest.getSomeState());
// Confirm that useExtension was called, and simultaneously acquire the lambda.
// ArgumentCaptor.capture() is a matcher, so every argument requires a matcher like eq.
verify(mockJdbi).useExtension(eq(OrgUnitDao.class), extensionConsumerCaptor.capture());
// Prepare the mock DAO and call the lambda.
when(mockDao.getFoo()).thenReturn("bar");
extensionConsumerCaptor.getValue().useExtension(mockDao);
// Assert anything that should be true after the lambda is called.
assertTrue(systemUnderTest.getSomeState());
}
Though lambdas reduce the boilerplate previously associated with anonymous inner classes, you may also prefer using the Captor style because it saves you from creating lengthy Answer implementations and hiding your test assertions or Mockito verifications in them. This is especially tempting if your project prefers BDD-style mocks with clear "given-when-then" structure (though my example more-closely resembles "given-when-then-when-then").
I am sure this is quite a common question now, but I really can't get away with this issue I am having on mocking private method which internally calls another method and returns a collection.
Class that I am testing has a public method which calls private method to get Collection object. I use PowerMock to create a spy of private method.
public void method1(String s)
{
Collection<Object> list = invokePrivate()
}
private Collection<Object> invokePrivate()
{
Wrapper wrapperObj = Factory.getInstance.getWrapper();
Collection<Object> list = wrapperObj.callWrapperMethod(); // This always calls into real method, instead of mocked version.
return list;
}
Test Class-:
So In order to test public method "method1" I create a spy using PowerMockito to spy over private method and return a demo list.
MainClass obj = new MainClass();
MainClass spy = PowerMockito.spy(obj);
PowerMockito.when(spy, method(MainClass.class, "inokePrivate"))
.thenReturn(list); // demo list which exists as a test class member.
Above calls into private method which in turns tries to call wrapperObj.callWrapperMethod() which resides in a different artifact and breaks there because some implementation it doesn't find there.
So I try to mock wrapperObj.callWrapperMethod.
WrapperClass wr = new WrapperClass();
WrapperClass spy1 = PowerMockito.spy(wr);
when(spy1.callWrapperMethod()).thenReturn(list) // demo list which exists as a test class member.
Above mocking again calls into actual implementation of callWrapperMethod() and breaks in there.
How can I prevent calling into actual implementation of wrapper method?
Few of the answers that helped me-:
Mockito:How to mock method called inside another method
Testing Private method using mockito
[UPDATE] -: as suggested as I did following-:
PowerMockito.doReturn(list).when(spy1).callWrapperMethod(); // This returns me demo list successfully.
But now when I call private method from PowerMockito control goes into invokePrivate method and again tries to call original callWrapperMethod instead of return list from spy version.
I suggest to not do it this way. Your private method should not retrieve the singleton factory object using a static method.
Static stuff breaks "easy" mocking; forces you to use "power" mocking; and thereby, creates more problems than it solves.
Change your code to use dependency injection. Do something like this:
class YourClass {
private final Factory factory;
public YourClass() {
this(Factory.getInstance(); }
YourClass(Factory theFactory) {
this.factory = theFactory;
...
This will allow you to use the second constructor in your unit test; to provide a (easily mocked) factory object for your class. Thereby you eliminate the whole need for PowerMock.
Long story short - when code is hard to test; change the code; and not the test. As a side effect, you are improving the quality of your code - because you loose the hard dependency on that singleton object.
And just to be complete: I also recommend to avoid "breaking" the Law of Demeter ( http://en.wikipedia.org/wiki/Law_of_Demeter ): if your class needs the wrapper; then it should hold a wrapper object; if it needs that factory; then it should hold a factory object. But you should not hold one object ... to retrieve another object from there, to run something on that second object. As you see - doing so leads exactly to the sort of problem that you are facing.
I am wondering if it is possible to define behaviour in easyMock that permits "intermediate" method calls.
Suppose I want to verify the behaviour of the doSomething method in this class:
class MyObject {
MyOtherObject inner; // init as constructor param...
void doSomething() {
inner.call1();
inner.call2();
}
public String toString() {
return "MyObject{" + inner.getName() + "}";
}
}
I had this test code:
MyOtherObject mocked = EasyMock.createStrictMock(MyOtherObject.class);
MyObject obj = new MyObject(myOtherObject);
// methods need to be called in this order
EasyMock.expect(mocked.call1()).once();
EasyMock.expect(mocked.call2()).once();
obj.doSomething();
When I change the implementation of MyObject.doSomething() to add logging using the toString() method, my tests fail because I did not add an expectation for MyOtherObject.getName().
Since I need a strict mock (with method order checking), simply adding this will not work: EasyMock.expect(mocked.getName()).andReturn("blahblah").anyTimes().
Is there an elegant way to solve this? For now, I have added this "anyTimes()" statement before every "real" expectation, but it renders my test unreadable and hard to maintain.
Or should I switch to another test framework?
If you don't care about the method call, for example logging, you can exclude it from any verification using a stub. So:
EasyMock.expect(mocked.getName()).andStubReturn("blah");
This will prevent your test from breaking by returning a value, but will not factor in to any sort of mocking verification, including strict mock ordering.