PowerMockito and AspectJ giving me NullPointerException - junit

Question

I have a Class under Test that looks like this:
import org.springframework.roo.addon.javabean.RooJavaBean;
import org.springframework.roo.addon.jpa.activerecord.RooJpaActiveRecord;
#RooJavaBean
#RooJpaActiveRecord(table="test_class", finders={ "findById" })
public class TestClass {
boolean test;
public static String returnSomething() {
return "X";
}
}
As you can see, it has Roo-Annotations and a static method I need to mock.
My test uses the (mocked) static method and also creates new objects from this class.
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PowerMockIgnore;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
#RunWith(PowerMockRunner.class)
#PrepareForTest(TestClass.class)
#PowerMockIgnore("javax.management.*")
public class PowerMockitoTest {
#Test
public void test() {
PowerMockito.mockStatic(TestClass.class);
PowerMockito.when(TestClass.returnSomething()).thenReturn("Y");
Assert.assertEquals("Y", TestClass.returnSomething());
TestClass x = new TestClass();
}
}
The call to new TestClass() gives me the following Exception:
java.lang.NullPointerException
at org.springframework.beans.factory.aspectj.AnnotationBeanConfigurerAspect.ajc$if$bb0(AnnotationBeanConfigurerAspect.aj:1)
at ....TestClass.<init>(TestClass.java:8)
and when I debug into the AnnotationBeanConfigurerAspect class I can see that the Configurable passed into this method is indeed null
public static final boolean ajc$if$bb0(Configurable c) {
return c.preConstruction();
}
Is this a bug in Powermock?
Are there any workarounds?
Versions used:
[INFO] +- junit:junit:jar:4.11:test
[INFO] | \- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] +- org.mockito:mockito-all:jar:1.9.5:test
[INFO] +- org.powermock:powermock-module-junit4:jar:1.5.3:test
[INFO] | \- org.powermock:powermock-module-junit4-common:jar:1.5.3:test
[INFO] | \- org.powermock:powermock-reflect:jar:1.5.3:test
[INFO] +- org.powermock:powermock-api-mockito:jar:1.5.3:test
[INFO] | \- org.powermock:powermock-api-support:jar:1.5.3:test
[INFO] +- org.powermock:powermock-module-junit4-rule:jar:1.5.1:test
[INFO] | +- org.powermock:powermock-classloading-base:jar:1.5.1:test
[INFO] | \- org.powermock:powermock-core:jar:1.5.1:test
[INFO] \- org.powermock:powermock-classloading-xstream:jar:1.5.1:test

Answer 1

Of course, this is not true, but well: PowerMock is a bug. The second you start using it you have to be prepared to spent a lot of time on such issues.
Especially when you start mixing power mock ... with another library that does byte code manipulation. That is simply calling for trouble.
So, the only answer that you will benefit from in the long run: don't do it. Do not use PowerMock.
Instead: understand that each and every situation that requires for PowerMock to enable testing (like static method calls) wants to tell you: "your design is bad, go fix it".
And if you really encounter situations that don't allow for design changes, then you might still prefer to not use PowerMock; worst case consider writing some real "functional" tests for that corner - just to avoid situations as the one you are facing right now.

Answer 2

I had similar problem in my code. Unfortunately I had to mock behavior of inner component, something like this:
public class LockWithRequestTimeout implements ReadWriteLock
//...
#TracePerformance // ----> this annotation somehow influence PowerMockito
#Override
public void lock()
{
try
{
while (!l.tryLock(1, TimeUnit.SECONDS))
{
PerformanceAdvice.checkRequestTimeout(() -> toString()); // ----> this is what i wanted to mock, PerformanceAdvice is AOP that handles TracePerformance annotation
}
}
catch (final InterruptedException e)
{
final String msg = "interrupted while waiting for " + this;
LogFactory.getLog(LockWithRequestTimeout.class).warn(msg);
Thread.currentThread().interrupt();
throw new RuntimeException(msg, e);
}
}
//...
My first thought was to mock PerformanceAdvice checkRequestTimeout method, but it behaved like in your example, I got NullPointerException.
My solution was to make small refactoring, I have extracted new method:
protected static void checkRequestTimeout(final Supplier<String> msg)
{
PerformanceAdvice.checkRequestTimeout(msg);
}
and instead of mocking PerformanceAdvice I mocked this new method in class LockWithRequestTimeout.
My proposition for you is to extract method
public static String returnSomething() {
return "X";
}
and move it to some kind of Utils? To other class that is not annotated by Roo

Answer 3

I filed a bug and provided a fix:
https://github.com/jayway/powermock/issues/676