Unit Testing involves the testing of individual units and components of a system.
Create unit tests for those parts of the code that have well defined consistent behaviour.
Write tests to reproduce bugs.Don’t go crazy now, only for those bugs that could make or break the application.
Test should be:
Don’t test trivial things: Although a unit test applies testing strategies to units of code, a line must be drawn as to how small a unit worth testing should be. If these units are too small then a developer might have many unit tests but their value and use could be brought into question.
Don’t create unit tests for functionality that is still in the ‘trial and error’ phase: Unit Tests work better when they are ensuring that a module’s or method’s state is retained rather on those functionality have not yet been settled on.