Testing legacy subsystem transformers between different versions of Wildlfy

The legacy web subsystem is still evolving. Thus we need to make the legacy web subsystem in WildFly evolve and test the transformers.
But testing the transformation between WildFly 8.0.0.Final and the next version of WildFly fails with the following exception :
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
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.jboss.as.subsystem.bridge.local.ScopedKernelServicesBootstrap.createChildClassLoaderKernelServices(ScopedKernelServicesBootstrap.java:85)
at org.jboss.as.subsystem.bridge.local.ScopedKernelServicesBootstrap.createKernelServices(ScopedKernelServicesBootstrap.java:53)
at org.jboss.as.subsystem.test.SubsystemTestDelegate$LegacyKernelServiceInitializerImpl.install(SubsystemTestDelegate.java:771)
at org.jboss.as.subsystem.test.SubsystemTestDelegate$LegacyKernelServiceInitializerImpl.access$700(SubsystemTestDelegate.java:644)
at org.jboss.as.subsystem.test.SubsystemTestDelegate$KernelServicesBuilderImpl.build(SubsystemTestDelegate.java:616)
at org.jboss.as.web.test.WebSubsystemTestCase.testTransformation_2_0(WebSubsystemTestCase.java:443)
at org.jboss.as.web.test.WebSubsystemTestCase.testTransformationWildFly8(WebSubsystemTestCase.java:427)
Caused by: java.lang.IllegalArgumentException: JBAS014880: No operation entry called 'add' registered at '[("subsystem" => "web")]'
at org.jboss.as.controller.operations.validation.OperationValidator.throwOrWarnAboutDescriptorProblem(OperationValidator.java:549)
at org.jboss.as.controller.operations.validation.OperationValidator.validateOperation(OperationValidator.java:123)
at org.jboss.as.model.test.ModelTestModelControllerService.boot(ModelTestModelControllerService.java:199)
at org.jboss.as.controller.AbstractControllerService.boot(AbstractControllerService.java:289)
at org.jboss.as.controller.AbstractControllerService$1.run(AbstractControllerService.java:256)
at java.lang.Thread.run(Thread.java:744)