Programmers usually neglect an even earlier defense level - static code analysis. Without denying the great benefit of unit-tests, I still think that although it is a good defense level, we can and must improve it greatly. Moreover, you may get a solid project "as a present" that merely has no unit-tests and they were not intended at all. Unit-tests become a burden if the project requirements change rapidly tests consume a lot of time to write and support it is not always easy to cover all the program branches with tests, etc. It is not always easy to create a unit-test for a function that requires a complicated procedure of preliminarily preparing the data. However, unit-tests have some disadvantages that I'm not going to discuss in detail here because all the programmers are aware of them. Sometimes tests are written earlier than the code they are intended to check. Usually the first level of error defense is creating unit-tests for the newly written code. But you may successfully fight many of them at much earlier stages of development process than usually. I would like to cite his thought that however skilled developers are, errors will appear in code all the same. Andrey Urazov discussed this thing in his interesting lecture "Quality-oriented programming" at the CodeFest 2010 conference. Does it seem to you that one can't make a mistake in every particular "if" operator? But I carried out such an experiment and wrote 200 comparisons - I did make an error once. It is the law of large numbers that works in this case. Still we don't manage to do that, do we? So, the approach "you should write without errors" doesn't work anyway.Įven a highly skilled programmer who takes his time makes errors from common misprints to errors in algorithms. The best way is certainly just to write without errors at all: imagine that you are only going to make an error but you slap your hand with the other and go on writing correct code.
From this we conclude that it's cheapest and easiest to eliminate an error while writing the code.
The earlier the developer finds an error in application code, the cheaper it is to fix it.
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