PowerMock trying to mock static getConnection gives illegalStateException: Failed to transform class

Question

I am trying to make static getConnection() method from a class JDBCConnectionFactory. I am using powerMock + mockito for mocking along with Junit4.

Solutions tried :

1. Googled for it and changed a lot of javassist.jar versions. None of them worked.
   
2. The below mentioned code works. But when I replace Another.class with JDBCConnectionFactory, it starts giving the below mentioned exception.
   

3. When I remove PrepareFortest annotation and try to run this JUNIT, it starts executing the getConnection method itself(which I want to mock).

   import org.junit.Test;
   import org.junit.runner.RunWith;
   import org.mockito.Mockito;
   import org.powermock.core.classloader.annotations.PrepareForTest;
   import org.powermock.modules.junit4.PowerMockRunner;
   
   @RunWith(PowerMockRunner.class)
   @PrepareForTest(AnotherClass.class)
   public class MockitoTester {
   
      @Test
      public void myTest() throws Exception {
   
         mockStatic(AnotherClass.class);
         Mockito.when(AnotherClass.getStaticString()).thenReturn("mock static string ");
         System.out.println(AnotherClass.getStaticString());
   
      }
   
   }
   

I am getting the below exception:

java.lang.IllegalStateException: Failed to transform class with name org.onesync.dq.gui.testng.testNG.MockitoTester. Reason: 3
    at org.powermock.core.classloader.MockClassLoader.loadMockClass(MockClassLoader.java:207)
    at org.powermock.core.classloader.MockClassLoader.loadModifiedClass(MockClassLoader.java:145)
    at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass(DeferSupportingClassLoader.java:67)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at java.lang.Class.forName0(Native Method) 
    at java.lang.Class.forName(Class.java:247)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:133)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:39)
    at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.createTestDelegators(AbstractTestSuiteChunkerImpl.java:217)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.<init>(JUnit4TestSuiteChunkerImpl.java:59)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.<init>(AbstractCommonPowerMockRunner.java:32)
    at org.powermock.modules.junit4.PowerMockRunner.<init>(PowerMockRunner.java:31)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:31)
    at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:24)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.<init>(JUnit4TestReference.java:33)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.<init>(JUnit4TestClassReference.java:25)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:48)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
    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.ArrayIndexOutOfBoundsException: 3
    at javassist.bytecode.ByteArray.write16bit(ByteArray.java:40)
    at javassist.bytecode.StackMapTable$Shifter.update(StackMapTable.java:744)
    at javassist.bytecode.StackMapTable$Shifter.sameFrame(StackMapTable.java:720)
    at javassist.bytecode.StackMapTable$Walker.stackMapFrames(StackMapTable.java:194)
    at javassist.bytecode.StackMapTable$Walker.parse(StackMapTable.java:179)
    at javassist.bytecode.StackMapTable$Shifter.doit(StackMapTable.java:714)
    at javassist.bytecode.StackMapTable.shiftPc(StackMapTable.java:693)
    at javassist.bytecode.CodeIterator.insertGap0(CodeIterator.java:676)
    at javassist.bytecode.CodeIterator.insertGap(CodeIterator.java:636)
    at javassist.bytecode.CodeIterator.insertGapCore(CodeIterator.java:467)
    at javassist.bytecode.CodeIterator.insertGap(CodeIterator.java:413)
    at javassist.expr.Expr.replace0(Expr.java:298)
    at javassist.expr.FieldAccess.replace(FieldAccess.java:213)
    at org.powermock.core.transformers.impl.MainMockTransformer$PowerMockExpressionEditor.edit(MainMockTransformer.java:276)
    at javassist.expr.ExprEditor.loopBody(ExprEditor.java:197)
    at javassist.expr.ExprEditor.doit(ExprEditor.java:90)
    at javassist.CtClassType.instrument(CtClassType.java:1289)
    at org.powermock.core.transformers.impl.MainMockTransformer.transform(MainMockTransformer.java:75)
    at org.powermock.core.classloader.MockClassLoader.loadMockClass(MockClassLoader.java:203)
    ... 29 more

Hope the above information helps. Any ideas/approaches/suggestions are welcome. Thanks

Answer 1

Sometimes you need to use the doReturn() syntax. Have you tried the following with JDBCConnectionFactory? I'll use your AnotherClass example:

@RunWith(PowerMockRunner.class)
@PrepareForTest(AnotherClass.class)
public class MockitoTester {

  @Test
  public void myTest() throws Exception {
    mockStatic(AnotherClass.class);
    PowerMockito.doReturn("mock static string ").when(AnotherClass.class, "getStaticString");
    System.out.println(AnotherClass.getStaticString());
  }
}

See also PowerMockitoStubber at https://www.javadoc.io/doc/org.powermock/powermock-api-mockito/1.5

Answer 2

please look ArrayIndexOutOfBoundsException when running PowerMock test, I solved by this way, update javassist.jar version