Spring Security NullPointerException with MockMvc and @Aspect around FilterChainProxy

Hi,

My intention was to set RequestRejectException to return 400 - BAD REQUEST instead of status 500. I know there is upcoming RequestRejectHandler in newer spring version but I do not want to upgrade it yet. So I did AOP around FilterChainProxy like this. I know that it is not clean way but if it works in production, should not it work in tests also?

``` @Component @Aspect class FilterChainProxyAdvice {

    @SuppressWarnings("checkstyle:IllegalThrows")
    @Around("execution(public void org.springframework.security.web.FilterChainProxy.doFilter(..))")
    public void handleRequestRejectedException(ProceedingJoinPoint pjp) throws Throwable {
        try {
            pjp.proceed();
        } catch (RequestRejectedException exception) {
            ((HttpServletResponse) pjp.getArgs()[1]).sendError(HttpServletResponse.SC_BAD_REQUEST);
        }
    }
}

It works great in non-mocked test environment. But when using MockMvc in tests, the exception is thrown:

java.lang.NullPointerException at org.springframework.security.web.FilterChainProxy.getFilters(FilterChainProxy.java:225) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.springframework.util.MethodInvoker.invoke(MethodInvoker.java:283) at org.springframework.test.util.ReflectionTestUtils.invokeMethod(ReflectionTestUtils.java:499) at org.springframework.test.util.ReflectionTestUtils.invokeMethod(ReflectionTestUtils.java:427) at org.springframework.security.test.web.support.WebTestUtils.findFilter(WebTestUtils.java:126) at org.springframework.security.test.web.support.WebTestUtils.getSecurityContextRepository(WebTestUtils.java:59) at org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors$SecurityContextRequestPostProcessorSupport.save(SecurityMockMvcRequestPostProcessors.java:611) at org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors$TestSecurityContextHolderPostProcessor.postProcessRequest(SecurityMockMvcRequestPostProcessors.java:701) at org.springframework.test.web.servlet.request.MockHttpServletRequestBuilder.postProcessRequest(MockHttpServletRequestBuilder.java:834) at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:173) at cz.multima.isic.eisi.integration.AbstractControllerTest.testAsync(AbstractControllerTest.java:69) at cz.multima.isic.eisi.integration.AbstractControllerTest.testAsync(AbstractControllerTest.java:61) at cz.multima.isic.eisi.integration.controller.SkodaControllerTest.testVyhledaniSkodyOsobniCisloAndIdknz(SkodaControllerTest.java:123) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) 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.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74) at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84) 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:251) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) 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$2.evaluate(ParentRunner.java:268) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)

```

Comment From: eleftherias

Thanks for getting in touch, but it feels like this is a question that would be better suited to Stack Overflow. We prefer to use GitHub issues only for bugs and enhancements. Feel free to update this issue with a link to the re-posted question (so that other people can find it) or add a minimal sample that reproduces this issue if you feel this is a genuine bug.