Object-oriented programming has some unique features which facilitate software reuse and component-based de- velopment. However, testing object-oriented programs us- ing only traditional techniques is unlikely to find the faults caused by these features. The problem is that few integra- tion testing techniques have been systematically studied or defined. We present a novel approach to generate and exe- cute test cases for object-oriented programs from UML di- agrams. We have designed an approach to implement test cases using the concept of Coordination Contract. A Coor- dination Contract, related to the idea of the active associ- ation class in UML, defines connections among a group of objects without interfering with their implementations. By using the contract, test case generation and execution can be completed automatically. A prototype tool has been de- veloped to automatically derive the contracts based on the mechanism of test case generation mentioned above.