Powermock: ClassNotFoundException when loading cglib enhanced classes created by Spring

[philwebb]

Originally raised on the Spring Boot issue tracker we're seeing different class loading behavior when the MockClassLoader is used and cglib enhanced are loaded.

A minimal project that reproduces the issue using PowerMock v1.6.5 and Spring Framework 4.3.2 can be found here.

Once imported into an IDE, if the following test is modified to directly use the SpringRunner then the test passes.

//@RunWith(SpringRunner.class)
@RunWith(PowerMockRunner.class)
@PowerMockRunnerDelegate(SpringRunner.class)
public class PowermockClassLoadTest {

    @Autowired
    private ConfigurableApplicationContext context;

    @Test
    public void testRest() throws Exception {
        BeanDefinition definition = context.getBeanFactory().getBeanDefinition("powermockClassLoadTest.Config");
        String className = definition.getBeanClassName();
        ClassUtils.forName(className, null);
    }

    @Configuration
    public static class Config {
    }

}

If the PowerMockRunner is used then the test fails with the following exception:

java.lang.ClassNotFoundException: com.example.PowermockClassLoadTest$Config$$EnhancerBySpringCGLIB$$e0ecd163
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at org.powermock.core.classloader.MockClassLoader.loadModifiedClass(MockClassLoader.java:190)
    at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass(DeferSupportingClassLoader.java:71)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:250)
    at com.example.PowermockClassLoadTest.testRest(PowermockClassLoadTest.java:26)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$2.call(DelegatingPowerMockRunner.java:148)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$2.call(DelegatingPowerMockRunner.java:140)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.withContextClassLoader(DelegatingPowerMockRunner.java:131)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.run(DelegatingPowerMockRunner.java:140)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:121)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:53)
    at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:59)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Digging in a little to the differences, it appears that ClassLoader.findClass(name) for the regular version returns a non-null result, where as in the failing version it returns null. Adding a conditional breakpoint on ClassLoader.loadClass(String name, boolean resolve) with the following condition should be enough to see the difference:

arg0.startsWith("com.example.PowermockClassLoadTest$Config$$EnhancerBySpringCGLIB") && !arg0.endsWith("Customizer")

[philwebb]

/cc @ramprasadjr

[thekingn0thing]

Thank you for reporting! I'll investigate the issue.

[philwebb]

Thanks!

[KomaliPathri]

Thanks

[gsugambit]

was this ever fixed? is there a way to use powermock with spring boot now?