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Mocking object instantiation with new in Java using PowerMock not working

I am trying to Unit Test a class in Java.
Code for this class: ToBeTested
public class ToBeTested {
private Collaborator collaborator;
public ToBeTested() {
System.out.println("ToBeTested: Constructor");
}
public void start() {
System.out.println("ToBeTested: Start");
collaborator = new Collaborator();
}
}
This class ToBeTested depends on another class, Collaborator.
Code for class: Collaborator
public class Collaborator {
Collaborator() {
System.out.println("Collaborator: Constructor");
}
}
While testing the class ToBeTested, I want to stub instantiation of Collaborator. That's a dependency I want to mock and I don't want it's constructor to be called.
I'm using Junit (v4.12) and PowerMock (v1.6.1).
Code for Test Class: TestToBeTested
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.easymock.annotation.Mock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import static org.powermock.api.easymock.PowerMock.*;
#RunWith(PowerMockRunner.class)
#PrepareForTest({ToBeTested.class, Collaborator.class})
public class TestToBeTested {
#Mock
private Collaborator collaborator;
private ToBeTested toBeTested;
#Before
public void setUp() throws Exception {
collaborator = createMock(Collaborator.class);
expectNew(collaborator.getClass()).andReturn(null);
toBeTested = new ToBeTested();
}
#Test
public void test() {
replayAll();
toBeTested.start();
verifyAll();
}
}
My understanding is that this will mock or stub out Collaborator and it's constructor should not be called. However, when I run the test, I notice that original constructor of Collaborator is called.
Output of test run:
ToBeTested: Constructor
ToBeTested: Start
Collaborator: Constructor
I'm very new to Java and Unit Testing in Java, so I apologize if I'm doing a very fundamental mistake here.
During my quest to find out the root cause, I have referred to following SO questions:
PowerMock's expectNew() isn't mocking a constructor as expected
PowerMock expectNew how to specify the type of the parameters
Not able to mock constructor using PowerMock
https://dzone.com/articles/using-powermock-mock
Thank you very much in advance for help/suggestions/feedback.

One possible reason that it might not be working could be this line:
expectNew(collaborator.getClass()).andReturn(null);
collaborator is a mocked instance which means it's "getClass()" method is going to return Collaborator$CGLIBMockedWithPowermock or something like that -- not the Collaborator class you want it to be. So you might get it to work simply by changing that line to:
expectNew(Collaborator.class).andReturn(null);

How to run PowerMock on dynamically created TestCase

I was trying to mock my test suites. My test framework creates test cases by scanning test files on disk. So each time the test cases are dynamically created.
I was trying to use PowerMock. Below is the thing I tried first.
public class GroupTestcase_T extends TestSuite {
static void run() {
scan();
junit.textui.TestRunner.run(g);
}
static void scan() {
// scan disk
for (MyTestCase t : tests) { addTest(t); }
}
}
#RunWith(PowerMockRunner.class)
#PrepareForTest(ClassToStub.class)
public class MyTestCase extends TestCase {
public MyTestCase(TestInfo info) {...}
#Override
protected void setUp() throws Exception {
PowerMockito.mockStatic(ClassToStub.class);
when(ClassToStub.methodToStub())
.thenReturn(new FakeProxy());
}
#Test
public void test() throws Exception {
// Test!
}
}
Above code seems not working:
Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
Those methods cannot be stubbed/verified.
2. inside when() you don't call method on mock but on some other object.
3. the parent of the mocked class is not public.
It is a limitation of the mock engine.
I traced the code and found that PowerMockRunner are not called at all.
Also I tried manually force Junit to run it with PowerMockRunner:
Result result = junit.run(new PowerMockRunner(MyTestCase.class));
PowerMockRunner has only one constructor that takes the test class as parameter. My test cases are different each time but all share the same class.
Any idea how to use PowerMock if TestCase are dynamically created?
I was using Junit 4 / PowerMock 1.5

You can generate your tests with the parameterized tests feature and apply the #PowerMockRule.
import static org.junit.Assert.assertTrue;
import java.util.Arrays;
import java.util.Collection;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.rule.PowerMockRule;
#RunWith(Parameterized.class)
#PrepareForTest(ClassToStub.class)
public class MyTestCase{
#Parameters
public static Collection<Object[]> scan() {
return Arrays.asList(new Object[][] {
{ new TestInfo() }, { new TestInfo() } });
}
#Rule
public PowerMockRule rule = new PowerMockRule();
public MyTestCase(TestInfo info) {
// ...
}
#Test
public void test() throws Exception {
PowerMockito.mockStatic(ClassToStub.class);
PowerMockito.when(ClassToStub.methodToStub()).thenReturn(new FakeProxy());
assertTrue(ClassToStub.methodToStub() instanceof FakeProxy);
}
}
Beware, in your example, you are mixing junit 3 (extends TestSuite, protected setUp) and junit 4 (#Test) test definitions.

Powermock : Mocked method still called

First of all, please know that I've searched SO before asking this question, but I was unable to find a satisfying answer.
I'm using JUnit4 and Powermock 1.5.5 (with mockito 1.9.5)
My problem is the following : in my unit tests, I need to mock a static method in a class I can't modify. I only want to mock one method, and not the whole class, so I went for a spy.
Here's what I have so far :
[...]
import static org.mockito.Matchers.*;
import static org.powermock.api.mockito.PowerMockito.*;
#RunWith(JUnitParamsRunner.class)
#ContextConfiguration(locations={"classpath:applicationContext-test.xml"},
loader=MockWebApplicationContextLoader.class)
#MockWebApplication(name="my-app")
#PrepareForTest(value = {
Role.class
})
public class MyTest {
#Rule
public PowerMockRule powerMockRule = new PowerMockRule();
#Before
public void setUp() throws Exception {
initSpring();
mockRoleServices();
}
private void mockRoleServices() throws Exception {
spy(Role.class);
RoleAnswer roleAnswer = new RoleAnswer(RoleEnum.ADMIN);
when(Role.hasAdministratorRole(anyLong(), anyLong(), anyLong()))
.then(roleAnswer);
}
private class RoleAnswer implements Answer<Boolean> {
private RoleEnum roleEnum;
private RoleAnswer(RoleEnum roleEnum) {
this.roleEnum = roleEnum;
}
#Override
public Boolean answer(InvocationOnMock invocation) throws Throwable {
return getRenderRequest().getUserRole() != null &&
getRenderRequest().getUserRole().equals(roleEnum);
}
}
}
Here's the problem : the method Role.hasAdministratorRole() is called instead of being mocked
Here's what I tried so far :
Using mockStatic(Role.class) instead of the spy() method. As expected, all methods are mocked, so I end up getting an NPE before Role.hasAdministratorRole() is called
Doing something like doAnswer(...).when(...). I get a runtime error with powermock telling me my mock is not complete (which actually confirms that something's wrong either with my code or with the lib itself)
Trying to declare the method by its name rather than calling it directly : when(Role.class, "hasAdministratorRole", long.class, long.class, long.class). Same behavior
A bunch of other things I don't recall anymore.
Your help will be greatly appreciated.
Thanks !
EDIT : Thanks to SrikanthLingala's answer, I was able to pinpoint the problem.
This didn't work :
when(Role.hasAdministratorRole(anyLong(), anyLong(), anyLong()))
.thenAnswer(roleAnswer);
but this did :
doAnswer(roleAnswer).when(Role.class, "hasSiteAdministratorRole",
anyLong(), anyLong(), anyLong());
So switching then when() and the answer() worked

As I do not have all of your implementations, I setup some dummy implementations and made a similar setup like yours. The below code works fine for me.
import static junit.framework.Assert.assertTrue;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
#RunWith(PowerMockRunner.class)
#PrepareForTest(value = {
Role.class
})
public class RoleTest {
#Test
public void mockRoleServices() throws Exception {
PowerMockito.spy(Role.class);
PowerMockito.doAnswer(new RoleAnswer(RoleEnum.ADMIN)).when(Role.class, "hasAdministratorRole", Mockito.anyLong(), Mockito.anyLong(), Mockito.anyLong());
Role.printOut();
assertTrue(Role.hasAdministratorRole(1, 1, 1));
}
private class RoleAnswer implements Answer<Boolean> {
private RoleEnum roleEnum;
private RoleAnswer(RoleEnum roleEnum) {
this.roleEnum = roleEnum;
}
public Boolean answer(InvocationOnMock invocation) throws Throwable {
return true;
}
}
}
Dummy Role class:
public class Role {
public static Boolean hasAdministratorRole(long a, long b, long c) {
System.out.println("Inside hasAdministratorRole");
return a + b + c < 0;
}
public static void printOut() {
System.out.println("Inside Printout");
}
}
My test case does not printout Inside hasAdministratorRole, but prints out Inside Printout
Hope this helps

Glad you have solved your issue, this just a warning for everyone else having a similar issue.
Project setup:
Powermock 1.5.5
Mockito 1.9.5
TestNG 6.8.8
Powermock is not taking into account mocks/spies created in a method annotated with #BeforeTest
E.g.:
#BeforeTest
public void setup(){
testee = mock(AClass.class);
}
It gets discarded and then it is entering the mocked method instead of returning the expected result OR throwing all kinds of strange exceptions. When moved to a common test method, it suddenly starts working:
#Test
public void test(){
AClass testee = mock(AClass.class);
....
}
Possibly it is a bug.

mockito, spy- not sure how it's done for partial mocking

I have a class, where i want to mock certain methods of the class and test the others. That is the only way i can verity and assert that it's working.
class UnderTest{
public void methodToTest(){
methodToCall1()
methodToCall2()
}
public void methodToCall1(){
}
public void methodToCall2(){
}
}
Now, since i want to test the first method, i want to create a partial mock of UnderTest so i can verify that those two methods were called.
How do i achieve this in Mockito?
Thanks for your help!

You mentioned you wanted to do two things:
1. Create real partial mocks
2. Verify method invocations
However, since your goal is to validate that methodToCall1() and methodToCall2() were actually invoked, all you need to do is spy on the real object. This can be accomplished with the following code block:
//Spy UnderTest and call methodToTest()
UnderTest mUnderTest = new UnderTest();
UnderTest spyUnderTest = Spy(mUnderTest);
spyUnderTest.methodToTest();
//Verify methodToCall1() and methodToCall2() were invoked
verify(spyUnderTest).methodToCall1();
verify(spyUnderTest).methodToCall2();
If one of the methods are not called, for example methodToCall1, an Exception will be thrown:
Exception in thread "main" Wanted but not invoked:
undertest.methodToCall1();
...

package foo;
import static org.mockito.Mockito.verify;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Spy;
import org.mockito.runners.MockitoJUnitRunner;
#RunWith(MockitoJUnitRunner.class)
public class FooTest {
#Spy
private UnderTest underTest;
#Test
public void whenMethodToTestExecutedThenMethods1And2AreCalled() {
// Act
underTest.methodToTest();
// Assert
verify(underTest).methodToCall1();
verify(underTest).methodToCall2();
}
}

How do I mock static methods in a class with easymock?

Suppose I have a class like so:
public class StaticDude{
public static Object getGroove() {
// ... some complex logic which returns an object
};
}
How do I mock the static method call using easy mock? StaticDude.getGroove().
I am using easy mock 3.0

Not sure how to with pure EasyMock, but consider using the PowerMock extensions to EasyMock.
It has a lot of cool functions for doing just what you need -
https://github.com/jayway/powermock/wiki/MockStatic

Easymock is a testing framework for "for interfaces (and objects through the class extension)" so you can mock a class without an interface. Consider creating an interfaced object with an accessor for your static class and then mock that acessor instead.
EDIT: Btw, I wouldn't recommend doing static classes. It is better to have everything interfaced if you are doing TDD.

Just in Case PowerMock is unavailable for any reason:
You could move the static call to a method, override this method in the instantiation of the tested class in the test class, create a local interface in the test class and use its method in the overidden method:
private interface IMocker
{
boolean doSomething();
}
IMocker imocker = EasyMock.createMock(IMocker.class);
...
#Override
void doSomething()
{
imocker.doSomething();
}
...
EasyMock.expect(imocker.doSomething()).andReturn(true);

Generally speaking, it is not possible to mock a static method without using some sort of accessor, which seems to defeat the purpose of using a static method. It can be quite frustrating.
There is one tool that I know of called "TypeMock Isolator" which uses some sort of Satanic Magic to mock static methods, but that tool is quite expensive.
The problem is, I know of no way to override a static method. You can't declare it virtual. you can't include it in an interface.
Sorry to be a negative nelly.

Adding an exemple on how to implements static mock along regular mock of injected classes with EasyMock / PowerMock, since the linked exemple only shows static mock.
And with the PowerMockRunner the #Mock services are not wired on the #TestSubject service to test.
Let say we have a service we want to test, ServiceOne :
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
#Service
public class ServiceOne {
#Autowired
private ServiceTwo serviceTwo;
public String methodToTest() {
String returnServ2 = serviceTwo.methodToMock();
return ServiceUtils.addPlus(returnServ2);
}
}
Which calls another service that we will want to mock, ServiceTwo :
import org.springframework.stereotype.Service;
#Service
public class ServiceTwo {
public String methodToMock() {
return "ServiceTwoReturn";
}
}
And which calls a final class static method, ServiceUtils :
public final class ServiceUtils {
public static String addPlus(String pParam) {
return "+" + pParam;
}
}
When calling ServiceOne.methodToTest() we get "+ServiceTwoReturn" as a return.
Junit Test with EasyMock, mocking only the injected ServiceTwo Spring service :
import static org.easymock.EasyMock.expect;
import static org.easymock.EasyMock.replay;
import static org.easymock.EasyMock.verify;
import static org.junit.Assert.assertEquals;
import org.easymock.EasyMockRunner;
import org.easymock.Mock;
import org.easymock.TestSubject;
import org.junit.Test;
import org.junit.runner.RunWith;
#RunWith(EasyMockRunner.class)
public class ExempleTest {
#TestSubject
private ServiceOne serviceToTest = new ServiceOne();
#Mock
private ServiceTwo serviceMocked;
#Test
public void testMethodToTest() {
String mockedReturn = "return2";
expect(serviceMocked.methodToMock()).andReturn(mockedReturn);
replay(serviceMocked);
String result = serviceToTest.methodToTest();
verify(serviceMocked);
assertEquals("+" + mockedReturn, result);
}
}
Junit Test with EasyMock & PowerMock, mocking the injected ServiceTwo Spring service but also the final class and its Static method :
import static org.easymock.EasyMock.expect;
import static org.junit.Assert.assertEquals;
import static org.powermock.api.easymock.PowerMock.createMock;
import static org.powermock.api.easymock.PowerMock.mockStatic;
import static org.powermock.reflect.Whitebox.setInternalState;
import org.easymock.Mock;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.easymock.PowerMock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
#RunWith(PowerMockRunner.class)
#PrepareForTest(ServiceUtils.class)
public class ExempleTest {
private ServiceOne serviceToTest;
private ServiceTwo serviceMocked;
#Before
public void setUp() {
serviceToTest = new ServiceOne();
serviceMocked = createMock(ServiceTwo.class);
// This will wire the serviced mocked into the service to test
setInternalState(serviceToTest, serviceMocked);
mockStatic(ServiceUtils.class);
}
#Test
public void testMethodToTest() {
String mockedReturn = "return2";
String mockedStaticReturn = "returnStatic";
expect(serviceMocked.methodToMock()).andReturn(mockedReturn);
expect(ServiceUtils.addPlus(mockedReturn)).andReturn(mockedStaticReturn);
PowerMock.replayAll();
String result = serviceToTest.methodToTest();
PowerMock.verifyAll();
assertEquals(mockedStaticReturn, result);
}
}