Decide Where to Put Test Code
This might seem like a strange heading, but what we need to consider is whether the nature of the development warrants a dedicated test harness program or whether a bolt-on module to the application itself would be suitable. Let's examine this further.
A major component-for example, a remote ActiveX server-has clearly defined public interfaces. We want to test that these interfaces all work correctly and that the expected results are obtained, and we also need to be sure that the appropriate error conditions are raised. Under these circumstances, it would be most suitable to write an application that links up to the remote server and systematically tests each interface. However, let's say a small, entirely self-contained GUI-based application is being created (no other components are being developed and used at the same time for the same deliverable). In this case, it might be more appropriate to write the test code as part of the application but have the test interfaces (for example, a menu item) only be visible if a specific build flag is declared.