Before we get our teeth too deeply into the Visual Basic way of programming, I think it’s worth reviewing the different levels of testing that apply to all software development projects regardless of the programming language or target platform.
The nature of testing is so varied in its requirements that it is difficult to give generalized definitions. What is appropriate for a small (one-person or two-person) application is totally unsuitable for a large (twenty-person) development, whereas the amount of formality that accompanies a large project would slow down the delivery of a small application by a wholly unreasonable amount. With this in mind, I have tried where appropriate to illustrate the relative scale that is necessary at each stage.