How do you Unit Test an .EXE with 3rd party dll?

Question

I'm still learning the dark arts of TDD and recently I've been trying to learn how to do TDD in VB6 and what I basically narrow down the list to was the free simplyvbunit and the most costly vbunit3.

My application is an richtext editor with plenty of 3rd party dll and I was scouring high and low in Google to find how to do unit test this exe file.

So my question is how do you unit test an exe file? Especially in the context for VB6 and if you have any good example with vbunit3 or simplyvbunit, you're simply a lifesaver as I'm drowing in the material right now and I still can't write one unit test yet :(

Edit

Actually the app consists of many forms, modules and class modules and when I compile it, it of course becomes nice neatly packaged .EXE file. And to make things more complicated there are quite a number of global variables flying around.

But my main intention is to unit test all or most breakable part of the code. And i want to ensure that i can keep the test and the code separate. So i thought that the best way to do is, is to somehow directly test the exe via add reference, etc.

Is there a better way to do this?

Answer 1

There is a difference between unit tests and integration tests. You don't unit test an executable. You unit test small, self-contained units of computation, like a method or a procedure, depending on what language you are using. An integration test would test larger components, like APIs, third-party components, or even executables to make sure that they work as expected for a given set of inputs (good or bad). While you can do some integration testing of APIs or plug-in components with unit testing tools, I don't think you'll find many unit testing tools that work to test executables. There are other types of test tools that will do a better job at this. Simply writing scripts that provide different types of inputs and check their outputs may be sufficient for many scenarios.

If you want to learn more about TDD and unit testing, you should apply it to functions or procedures in VB6 -- although, I'd recommend VB.NET (or C#) and doing object-oriented development. Typically the tools are oriented towards OO-style programming.