Mockito throws NullPointer when creating a mock object

java mockito powermock
Jorn picture Jorn · Mar 26, 2013 · Viewed 14.5k times · Source

I have an integration test in which some set up is done using Guice. I'm using Mockito to mock some of the dependencies. This has worked fine for me until now. I needed to use PowerMock for some other dependency. Now Mockito is throwing a NullPointerException while loading one of its own classes:

java.lang.ExceptionInInitializerError
    at org.mockito.internal.exceptions.stacktrace.ConditionalStackTraceFilter.<init>(ConditionalStackTraceFilter.java:17)
    at org.mockito.exceptions.base.MockitoException.filterStackTrace(MockitoException.java:30)
    at org.mockito.exceptions.base.MockitoException.<init>(MockitoException.java:19)
    at org.mockito.exceptions.misusing.MockitoConfigurationException.<init>(MockitoConfigurationException.java:18)
    at org.mockito.internal.configuration.ClassPathLoader.loadImplementations(ClassPathLoader.java:145)
    at org.mockito.internal.configuration.ClassPathLoader.findPluginImplementation(ClassPathLoader.java:110)
    at org.mockito.internal.configuration.ClassPathLoader.findPlatformMockMaker(ClassPathLoader.java:106)
    at org.mockito.internal.configuration.ClassPathLoader.<clinit>(ClassPathLoader.java:59)
    at org.mockito.internal.util.MockUtil.<clinit>(MockUtil.java:21)
    at org.mockito.internal.MockitoCore.<init>(MockitoCore.java:40)
    at org.mockito.Mockito.<clinit>(Mockito.java:932)
    <snip my test code and some Guice>
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.junit.internal.runners.ClassRoadie.runBefores(ClassRoadie.java:56)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:43)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:120)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:101)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:53)
    at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:53)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Caused by: java.lang.NullPointerException
    at org.mockito.internal.exceptions.stacktrace.StackTraceFilter.<clinit>(StackTraceFilter.java:21)
    ... 39 more

the (trimmed down) code:

@PrepareForTest(MyModule.class)
@RunWith(PowerMockRunner.class)
public class MyTest {
    @BeforeClass
    public static void setUp() {
        Injector injector = Guice.createInjector(...);
        MyModule module = PowerMockito.mock(MyModule.class);
        injector = injector.createChildInjector(...); // Fails in another Mockito.mock() call before it gets to use the mocked Module.
    }
}

I couldn't find anything about this being a known bug in Mockito. Does anyone have a suggestion on how to solve this?

Answer

rajesh picture rajesh · Mar 26, 2013

Check this issue

This seems to happen when a mock is created at instantation time.

If I set up my mocks in an @Before method the issue goes away.

Related questions

Mock a constructor with parameter

I have a class as below: public class A { public A(String test) { bla bla bla } public String check() { bla bla bla } } The logic in the constructor A(String test) and check() are the things I am trying to mock. …

Read More
PowerMockito mock single static method and return object

I want to mock a static method m1 from a class which contains 2 static methods, m1 and m2. And I want the method m1 to return an object. I tried the following 1) PowerMockito.mockStatic(Static.class, new Answer<Long&…

Read More
How to mock private method for testing using PowerMock?

I have a class which I would like to test with a public method that calls private one. I'd like to assume that private method works correctly. For example, I'd like something like doReturn....when.... I found that there is …

Read More