According to the PowerMock docs, I should be able to run using a PowerMockRule
instead of @RunWith(PowerMockRunner.class)
and get the same results.
I seem to have found a case where this isn't true.
The below sample runs fine:
package com.test.powermockstatics;
import static org.junit.Assert.assertEquals;
import static org.powermock.api.mockito.PowerMockito.mockStatic;
import static org.powermock.api.mockito.PowerMockito.when;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
final class FinalClassWithStaticCall {
public static int getIntStatic() {
return 1;
}
}
@RunWith(PowerMockRunner.class)
@PrepareForTest(FinalClassWithStaticCall.class)
public class TestStaticMockingWithoutPowerMockRunner {
@Test
public void testStaticCall() {
mockStatic(FinalClassWithStaticCall.class);
when(FinalClassWithStaticCall.getIntStatic()).thenReturn(2);
assertEquals(FinalClassWithStaticCall.getIntStatic(), 2);
}
}
But when switched to a rule like so:
package com.test.powermockstatics;
import static org.junit.Assert.assertEquals;
import static org.powermock.api.mockito.PowerMockito.mockStatic;
import static org.powermock.api.mockito.PowerMockito.when;
import org.junit.Rule;
import org.junit.Test;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.agent.PowerMockAgent;
import org.powermock.modules.junit4.rule.PowerMockRule;
final class FinalClassWithStaticCall {
public static int getIntStatic() {
return 1;
}
}
@PrepareForTest(FinalClassWithStaticCall.class)
public class TestStaticMockingWithoutPowerMockRunner {
static {
PowerMockAgent.initializeIfNeeded();
}
@Rule
public PowerMockRule rule = new PowerMockRule();
@Test
public void testStaticCall() {
mockStatic(FinalClassWithStaticCall.class);
when(FinalClassWithStaticCall.getIntStatic()).thenReturn(2);
assertEquals(FinalClassWithStaticCall.getIntStatic(), 2);
}
}
I get the following exception:
java.lang.IllegalArgumentException: Cannot subclass final class class com.test.powermockstatics.FinalClassWithStaticCall at org.mockito.cglib.proxy.Enhancer.generateClass(Enhancer.java:447) at org.mockito.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25) at org.mockito.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:217) at org.mockito.cglib.proxy.Enhancer.createHelper(Enhancer.java:378) at org.mockito.cglib.proxy.Enhancer.createClass(Enhancer.java:318) at org.mockito.internal.creation.jmock.ClassImposterizer.createProxyClass(ClassImposterizer.java:110) at org.mockito.internal.creation.jmock.ClassImposterizer.imposterise(ClassImposterizer.java:62) at org.powermock.api.mockito.internal.mockcreation.MockCreator.createMethodInvocationControl(MockCreator.java:111) at org.powermock.api.mockito.internal.mockcreation.MockCreator.mock(MockCreator.java:60) at org.powermock.api.mockito.PowerMockito.mockStatic(PowerMockito.java:70) at com.test.powermockstatics.TestStaticMockingWithoutPowerMockRunner.testStaticCall(TestStaticMockingWithoutPowerMockRunner.java:30) 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:606) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.powermock.modules.junit4.rule.PowerMockStatement.evaluate(PowerMockRule.java:49) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) 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)
I am following the recommendation from the docs to:
put powermock-module-junit4-rule-agent before junit in the classpath
Does anyone know the official word if this is a bug in PowerMock or the desired behavior (i.e., you simply can't mock a static
method on a final
class using a PowerMockRule
)?
EDIT:
Please see the clarifying details in the comments under Gábor Lipták's answer. I do not want to use a statically loaded Agent, since it appears the dynamically loaded Agent ought to be capable of getting the job done?
I know starting the agent statically will work. (Unfortunately this is not an option in my project.) So does anyone know if the failure of the dynamically loaded Agent is a bug in PowerMock? Or a known limitation; and why?