: This article proposes a new method for creating test software for object-oriented systems using a genetic programming approach. It is believed that this approach is advantageous over the more established search-based test-case generation approaches because the test software is represented and altered as a fully functional computer program. Genetic programming (GP) uses a tree-shaped data structure which is more directly comparable and suitable for being mapped instantly to syntax trees commonly used in computer languages and compilers. These structures can be manipulated and executed directly, bypassing intricate and error prone conversion procedures between different representations. In addition, tree structures make more operations possible, which keep the structure and semantics of the evolving test software better intact during program evolution, compared to linear structures. This speeds up the evolutionary program generation process because the loss of evolved structures due to...