UnfinishedMockingSessionException with inner test classes

[mouyang]

This appears to be a regression from 1.10.19 and 2.x-beta since it was reported as fixed in #353, but I was unable to get the sample test class to work in the release/2.x branch (also reported to fail in 2.13.0, 2.1.0-beta.125, and master too). The root cause is JUnitRule attempting to add a UniversalTestListener a second time to a ThreadSafeMockingProcess.

Sample Test class

@RunWith(HierarchicalContextRunner.class)
public class HierarchicalMockitoTest {
    @Rule
    public MockitoRule mockitoRule = MockitoJUnit.rule();

    @Mock
    private Runnable runnable;

    public class Context {
        @Test
        public void test() throws Exception {
            runnable.run();
        }
    }
}

Exception Thrown

org.mockito.exceptions.misusing.UnfinishedMockingSessionException: 
Unfinished mocking session detected.
Previous MockitoSession was not concluded with 'finishMocking()'.
For examples of correct usage see javadoc for MockitoSession class.
	at org.mockito.internal.junit.JUnitRule$1.evaluate(JUnitRule.java:42)
	at org.mockito.internal.junit.JUnitRule$1.evaluateSafely(JUnitRule.java:52)
	at org.mockito.internal.junit.JUnitRule$1.evaluate(JUnitRule.java:43)
	at de.bechte.junit.runners.context.statements.StatementExecutor.execute(StatementExecutor.java:28)
	at de.bechte.junit.runners.context.processing.MethodExecutor.run(MethodExecutor.java:83)
	at de.bechte.junit.runners.context.processing.MethodExecutor.run(MethodExecutor.java:57)
	at de.bechte.junit.runners.context.statements.RunChildren.evaluate(RunChildren.java:38)
	at de.bechte.junit.runners.context.statements.RunAll.evaluate(RunAll.java:27)
	at de.bechte.junit.runners.context.statements.StatementExecutor.execute(StatementExecutor.java:28)
	at de.bechte.junit.runners.context.HierarchicalContextRunner.run(HierarchicalContextRunner.java:134)
	at de.bechte.junit.runners.context.processing.ContextExecutor.run(ContextExecutor.java:26)
	at de.bechte.junit.runners.context.processing.ContextExecutor.run(ContextExecutor.java:15)
	at de.bechte.junit.runners.context.statements.RunChildren.evaluate(RunChildren.java:38)
	at de.bechte.junit.runners.context.statements.RunAll.evaluate(RunAll.java:27)
	at de.bechte.junit.runners.context.statements.StatementExecutor.execute(StatementExecutor.java:28)
	at de.bechte.junit.runners.context.HierarchicalContextRunner.run(HierarchicalContextRunner.java:134)
	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:678)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

I have a fix in progress which involves lazy initialization (
https://github.com/mouyang/mockito/commit/540ad11d5a0d4066a73b3e46a932733d7ed816df). I haven’t submitted a PR yet because I’m waiting for the library I used to reproduce the issue to make a new release with a required fix bechte/junit-hierarchicalcontextrunner#32. Also I need to clean up the commit to use reference this issue instead of 353. I suppose I can move forward with a PR if there was a way to reproduce the issue without using that library but I haven’t thought of a way to do that.

Thanks to @UrsMetz for verifying the regression and providing a sample test class.