The implementation of an efficient automatic test generation scheme for black-box testing environment is discussed. It uses checkpoint encoding and antirandom testing schemes. Checkpoint encoding converts test generation to a binary problem. The checkpoints are selected to probe the input space such that boundary and illegal cases are generated in addition to valid cases. Antirandom testing selects each test case such that it is as different as possible from all the previous tests. The implementation is illustrated using benchmark examples that have been used in the literature. Use of random testing both with checkpoint encoding and without is also reported. Comparison and evaluation of the effectiveness of these methods is also presented. Implications of the observations for larger software systems are noted. Overall, antirandom testing has higher code coverage than encoding random testing, encoding random testing has higher code coverage than pure random testing.