Using the <flex:message-broker/> tag will not work in a standalone integration test (as you are trying to run) unless you do something to mock the Servlet environment.
Though this can be done (for an example see org.springframework.flex.config.AbstractFlexConfig urationTests and org.springframework.flex.config.MessageBrokerConte xtLoader in the Spring BlazeDS source distro), the more common approach is to separate things that have such environmental dependencies in such a way that they don't get loaded in your integration tests.
Jeremy Grelle
Staff Engineer, Web Products Team
SpringSource