This paper discusses the approaches used for integration testing of object oriented applications that have been modeled in unified modeling language. It explains integration testing and the test design patterns used far integration testing. Integration problems arise due to lack of interoperability among different components. Strategies for class test order for integration testing have been discussed in this paper, as integration test order specifies the estimated cost for developing stubs' and drivers. Semantics for UML diagrams enable the dependency analysis of components for integration testing. Techniques far replacing classes by stubs for breaking cycles among them have been discussed to enable stepwise integration testing.