This paper describes an automated approach to generating test cases for an object-oriented class. The approach is derived from the state-based testing method and refers to a state machine from which a threaded a multi-way tree (duplicating the behaviour of the state machine) is produced. Finally, all possible sequential test cases can be automatically created, when our test case generator parses the tree.In practice, on examination of the state machine can result in different versions of implemented classes being produced by different programmers. Moreover, a design transition, in the design state machine, may map to more than one member function in the implemented class. If a class is automatically tested with a test case file, the test cases should invoke the member functions of the class under test instead of the transition names of its design state machine. The test case generator discussed in this paper will refer to the implementation state machine rather than the design state machine. Following the implementation state machine, to build a test case generator (a threaded multi-way tree), which completely duplicates the behaviour of the state machine.