TestNG tests fail in Seam project + AS6

Steps to reproduce:

1.) Create new seam web project (EAR)
2.) Create new seam action (using new action wizard)
3.) Run the generated test (i.e. HelloTest.java) as a TestNG test.
4.) Add the following VM argument to the test run configuration -Dsun.lang.ClassLoader.allowArraySyntax=true
5.) Run the test again

The test fails with the following stacktrace:

FAILED: test_hello
java.lang.AssertionError: java.lang.UnsupportedOperationException
at org.jboss.seam.mock.AbstractSeamTest$Request.onException(AbstractSeamTest.java:463)
at org.jboss.seam.mock.AbstractSeamTest$Request$2.doFilter(AbstractSeamTest.java:512)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:206)
at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388)
at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515)
at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)
at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
at org.jboss.seam.mock.AbstractSeamTest$Request.run(AbstractSeamTest.java:499)
at org.domain.jbtoolsear.test.HelloTest.test_hello(HelloTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:74)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:673)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:846)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1168)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
at org.testng.TestRunner.runWorkers(TestRunner.java:1125)
at org.testng.TestRunner.privateRun(TestRunner.java:749)
at org.testng.TestRunner.run(TestRunner.java:600)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:317)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:312)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:274)
at org.testng.SuiteRunner.run(SuiteRunner.java:223)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:954)
at org.testng.TestNG.runSuitesLocally(TestNG.java:883)
at org.testng.TestNG.run(TestNG.java:817)
at org.testng.remote.RemoteTestNG.run(RemoteTestNG.java:110)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:205)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:174)
Caused by: java.lang.UnsupportedOperationException
at javax.faces.context.FacesContext.getAttributes(FacesContext.java:137)
at javax.faces.component.UIViewRoot.setViewId(UIViewRoot.java:325)
at org.jboss.seam.mock.MockViewHandler.createView(MockViewHandler.java:28)
at org.jboss.seam.jsf.SeamViewHandler.createView(SeamViewHandler.java:68)
at org.jboss.seam.mock.AbstractSeamTest$Request.restoreViewPhase(AbstractSeamTest.java:734)
at org.jboss.seam.mock.AbstractSeamTest$Request.emulateJsfLifecycle(AbstractSeamTest.java:591)
at org.jboss.seam.mock.AbstractSeamTest$Request.access$100(AbstractSeamTest.java:177)
at org.jboss.seam.mock.AbstractSeamTest$Request$2.doFilter(AbstractSeamTest.java:505)
... 45 more