[keshab]

I couldn't agree more with you about nesting loops. It seems clever at the moment when you're writing but when you have to come back after a while or worse, another developer has to, it becomes a nightmare.

I would also go a bit further and put nesting if statements. Sometimes it's really required but other times nesting can be avoided. I try to avoid nesting as much as possible.

[mikekchar]

Quick tip: extract the contents of loops out into functions. That allows you to test the function outside of the context of the loop. It makes it easy to test boundary conditions and other exceptions. Often it is unnecessary to actually test the loop.

This is also true of branches. If you have an if statement (or other branch), consider extracting the contents of each half out. It allows you to test each half independently. If you have nested branches, you need to have 2^n tests (where n is the number of nested branches). If you extract the contents, then you need 2n tests.

This is one of the reason for unit rather than integration tests: you can dramatically reduce the number of tests while still getting full test coverage. Of course the downside is decomposing the structure of the code more than you might be used to. It's always a judgement call.