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PowerMockito doesn't mock the new instance called in the tested class

I have the following class where, in the constructor, I call another constructor to build a field of the class:
public class ClassIWantToTest {
private ClassIWantToMock anotherClass;
public ClassIWantToTest() {
//some stuff
anotherClass = new ClassIWantToMock(); //<-- call constructor to build the field
//some other stuff
}
}
When I test the class ClassIWantToTest, I want to mock the instance of ClassIWantToMock.
Hence, I've set up my test as follows:
#RunWith(PowerMockRunner.class)
#PrepareForTest(ClassIWantToMock.class)
public class ClassIWantToTest_Test {
#Test
public void myFirstTest() {
ClassIWantToMock myMock = PowerMockito.mock(ClassIWantToMock.class);
PowerMockito.whenNew(ClassIWantToMock.class).withAnyArguments().thenReturn(myMock);
ClassIWantToTest test = new ClassIWantToTest(); //<-- not mocked
}
}
However, in the last line of code in the test (where I make a new of the class I want to test), the constructor of ClassIWantToMock is still called.
I've searched other examples on Stack Overflow (and in documentation), but it seems that it should be done like this. What am I forgetting/doing wrong?

It was indeed a simple mistake. If the class ClassIWantToMock is initialized inside ClassIWantToTest, then also ClassIWantToTest should be prepared for test.
I replaced this:
#PrepareForTest(ClassIWantToMock.class)
with this:
#PrepareForTest({ClassIWantToTest.class,ClassIWantToMock.class})
... and it worked fine.

How to capture incoming parameters with EasyMock.capture?

I'm testing a class and wanted to monitor calls to a specific method, namely to save the calling parameters for later analysis.
Testing is done with EasyMock, so it was logical to use EasyMock.capture feature. However, the examples that I managed to find do not work for me - I get the following compile error at the line with capture:
expect(T) in EasyMock cannot be applied to (void)
reason: no instance of type variable T exist so that void conforms to T
It would be great if somebody could point out my mistake(s) for me. Below is a code snippet:
import static org.easymock.EasyMock.capture;
import org.easymock.Capture;
import org.easymock.CaptureType;
import org.easymock.EasyMock;
import org.junit.Before;
class B {
}
class A {
public void doSomething(B input) {
}
}
public class ATest {
private Capture<B> capturedData;
private A testObject;
#Before
private void setUp() {
capturedData = EasyMock.newCapture(CaptureType.ALL);
testObject = EasyMock.createNiceMock(A.class);
EasyMock
.expect(testObject.doSomething(capture(capturedData)))
.anyTimes();
}
}
Thanks a lot in advance!

Your problem is not related to the capture, but to the return type of your doSomething() method:
Since A.doSomething(B input) is of return type void, you don't expect the method to return anything, thus you cannot use EasyMock.expect() for it. Instead, simply invoke the method and use EasyMock.expectLastCall(), like so:
testObject.doSomething(capture(capturedData));
EasyMock.expectLastCall().anyTimes();
EasyMock.expectLastCall() declares that you expect the last method invocation before expectLastCall() to be executed. You can then handle it just like expect(), e.g. add anyTimes() to it.

Is it possible to invoke mocked object's method?

I have, for example, this class:
public class A {
private List<String> list;
public A(B b){
list = b.getList();
}
public List<String> someMethod(){
return list;
}
}
I want to unit test someMethod without invoking constructor. I use reflection to set list.
The problem is that I don't want to create B class object and I cannot mock it since it will cause NPE.
So my question is:
How to test someMethod without calling constructor of A? Is there any way to mock class A and doesn't lose posibility to call methods?
Creating constructor with zero arguments is not a solution.
Note: I don't want to change any part of A class. I'm asking if it is possible to perform this test without adding or changing anything in A class.

You can test class A without calling it's constructor by Mockito. Not sure if I really understand your requirement but the following codes work for me.
import org.junit.Test;
import org.springframework.test.util.ReflectionTestUtils;
import java.util.ArrayList;
import java.util.List;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;
public class ATest {
#Test
public void test() {
A a = mock(A.class);
when(a.someMethod()).thenCallRealMethod();
List<String> listInA = new ArrayList<String>();
ReflectionTestUtils.setField(a, "list", listInA);
assertThat(a.someMethod(), is(listInA));
}
}

You should mock out the collaborators to your class -- that means that you can create an instance of the class being tested, and pass in mocks, configured to 'do the right thing' when it's methods are called.
In your example, you want to create a mock B, and use it like this:
#RunWith(MockitoJUnitRunner.class)
class myTest {
#Mock private B b;
public void someMethod() {
doReturn(new ArrayList<String>()).when(b).getList();
A a = new A(b);
assertEquals("result", a.someMethod().get(0));
}
}

I don't want to create B class object
Add a constructor or factory method which doesn't require a B.
public A(B b){
this(b.getList());
}
/* package local */ A(List<String> list){
this.list = list;
}
By making the constructor package local it can be accessed by unit tests in the same package.
How to test someMethod without calling constructor of A?
You can use
A a = theUnsafe.allocateInstance(A.class);
but this is not recommended unless you have no other option e.g. deserialization.

Test if another method was called

So I'm sure there is something like this out there but I have been searching for an hour and haven't found exactly what I am looking for. say I have a class that looks like this:
public class MyClass
{
public void myMethod(boolean shouldCallOtherMethod)
{
if(shouldCallOtherMethod)
{
otherMethod();
}
}
public void otherMethod()
{
System.out.println("Called");
}
}
How do I make something like this work?
#Test
public void shouldCallMethod()
{
MyClass myClass = new MyClass();
myClass.myMethod(true)
// verify myClass.otherMethod method was called
}

Using Mockito, you can do spying on real objects like this:
import org.junit.Test;
import static org.mockito.Mockito.*;
public class MyClassTest {
#Test
public void otherMethodShouldBeCalled() {
MyClass myClass = new MyClass();
MyClass spy = spy(myClass);
spy.myMethod(true);
verify(spy).otherMethod();
}
}
There are some gotchas, so take a look at the relevant documentation as well.

Suppose MokeysClass has a constructor declared like this, where Foo is some other class.
public MokeysClass(String name, int counter, Foo myFoo)
I would write my test like this.
#RunWith(MockitoJUnitRunner.class)
public class TestArray {
#Mock
private Foo mockMyFoo;
private String nameToInject = "Mokey";
private int counterToInject = 42;
#Spy
private MokeysClass toTest = new MokeysClass(nameToInject, counterToInject, mockMyFoo);
#Test
public void shouldCallMethod() {
toTest.myMethod(true);
verify(toTest).otherMethod();
}
}
so that I am explicitly stating which constructor to call when I create my test object, and what arguments to pass to it.
There are some reasons not to rely on #InjectMocks to do this step for me, particularly if the class being tested is more complex and has more than one constructor. Mockito chooses the constructor that has the most arguments, but if there are several constructors with the same number of arguments, Mockito could choose any of the constructors; that is, the behaviour is undefined.
Once Mockito has chosen a constructor, it checks whether that constructor can in fact be used for constructor injection. Constructor injection will not be used if
one or more of the parameters of the chosen constructor is a primitive type,
the type of one or more of the parameters of the chosen constructor is a final class,
the type of one or more of the parameters of the chosen constructor is a private class,
the only constructor of the class is the default constructor.
If any one of these conditions holds, for the constructor that Mockito chose, then constructor injection won’t be used. In this case, the class must have a default constructor, otherwise Mockito will throw an exception.
The complexity of the criteria which Mockito uses when choosing whether to apply constructor injection implies that adding or removing a constructor, or changing the parameters of a constructor, can make Mockito switch from using constructor injection to using setter and field injection; or from using setter and field injection to using constructor injection. This can occur even if the constructor that is changed is not the one that will be used for constructor injection.
As a result, any test that uses constructor injection is automatically quite brittle; in the sense that changes that are not directly related to the test itself can cause the test to fail. Such failures can be difficult to troubleshoot.
The #InjectMocks annotation was designed for use with frameworks such as Spring that do dependency injection; and for tests of classes that use Spring, it can be invaluable. But if dependency injection is not part of your class, I would strongly recommend avoiding #InjectMocks on account of its brittleness. You really want your test code to be as easy to maintain and to troubleshoot as your production code is.

This is not recommended, but you can spy real object :)
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Spy;
import org.mockito.runners.MockitoJUnitRunner;
import static org.mockito.BDDMockito.verify;
#RunWith(MockitoJUnitRunner.class)
public class MyClassTest {
#Spy
private MyClass sut; // System Under Test
#Test
public void shouldCallMethod() {
// when
sut.myMethod(true);
// then
verify(sut).otherMethod();
}
}
Result:
Tests Passed: 1 passed in 0,203 s
After changing code: sut.myMethod(false);
Wanted but not invoked:
sut.otherMethod();
-> at my.custom.MyClassTest.shouldCallMethod(MyClassTest.java:23)
Source: Spying on real objects
Magic version with constructor injection
#Mock
private LexAnalyzer lexAnalyzer;
#Spy
#InjectMocks
private SyntaxAnalyzer sut; // System Under Test
#Test
public void shouldCallMethod() {
// when
sut.myMethod(true);
// then
verify(sut).otherMethod();
}
SyntaxAnalyzer.java
public class SyntaxAnalyzer {
private final LexAnalyzer lexAnalyzer;
public SyntaxAnalyzer(LexAnalyzer lexAnalyzer) {
this.lexAnalyzer = lexAnalyzer;
}
...
Tested, works ;)

I think you want to look at Mock objects. You can create a mock of MyClass, then set expectations that otherMethod() is called when you call myMethod and fails if it was not called.
Here is a pretty good overview of them for java - http://www.scalatest.org/user_guide/testing_with_mock_objects
One other major benefit of using Mocks, you can avoid side affects, like logging to NSLog or hitting a web server or printing) in your test.

Abstracting a Test Class

I have a few tests right now that uses PowerMock and Mockito to "mock objects". The problem is, all those tests create the same mocks over and over again. Is it possible to have an abstract class from which my test derive that pre-mocks these objects ?
Example :
public abstract class AbstractTest {
public void initialize() {
PowerMockito.mockStatic(StaticMock.class);
when(StaticMock.doSomething()).thenReturn(true);
}
}
#RunWith(PowerMockRunner.class)
#PrepareForTest(StaticMock.class) // BanManager.class contains static methods
public class Test extends AbstractTest {
#SuppressWarnings("serial")
#Test
public void testWithPerms() {
initialize();
SomeObject obj = new SomeObject();
obj.doSomething();
PowerMockito.verifyStatic();
Static.verifyIsCalled();
}
}
How could I do something like the above that actually worked ? This gives me Inconsistent stackmap frames
EDIT : Thank you for your answer. My problem was actually due to me using a PowerMock version incompatible with java 7. Still, your indication will be helpful.

Of course this is possible. If you put the #Before annotation on a method in the base class, it will run at the beginning of every test in any subclass. Alternatively, you can put this off in some kind of factory class that is used in all your tests.