Yesterday I had a great conversation with one of my friend about few things one of them was Unit testing. He is a big proponent of Unit Testing. Good unit testing (see I did not write more unit testing) could help identify and resolve the bugs in the code very early. This also helps code maintenance. I use unit testing where ever and when ever possible. I will not sit and break my head over how will I do unit test when I develop form over data patterns. On the flip side when you develop a program that involves some kind of logic that manipulate data then for sure you need to identify the components and test it.
This was one of my friend example, why would we need unit testing, lets assume _a and _b are variable and instead of doing if (_a == _b) if you would do it, if (_a = _b) then you have problem. If you would write an unit test for it, you will catch it early enough. On the side note, this condition will not even compile in C#, because compiler will complain, it can not convert integer to bool implicitly. Anyway, you got the point.
One very import point I want to make is how many unit test you write? Write enough to do good code coverage. If you have a method which takes bunch of parameters and you are asserting against some values, in older version of NUnit, you would write individual methods for each assertion. With latest version of NUnit you can write the single test and decorate it with all the assertion saves lots of code duplication. It also make code maintenance easy. So please check out latest version of NUnit.
If you are lazy or do not want to do unit test yet you need to do please your boss, here is a short cut, use Microsoft PEX. In this, you point a method and PEX will create all the possible scenario test cases with all possible input parameters.
Now that I am doing more and more Silver Light + RIA, I need to do more reading on how I can test the code good. Any of you are using testing for these platform, drop me a mail.