There's a good post over on the NetTuts.com site today talking about unit testing, the myths around code coverage and why it may not be as important as you think.
Most cubicle workplaces disappeared and programmers started loving their craft. With the advent of Agile techniques and the Software Craftsmanship movement, many new tools emerged to help the programmer and the process. TDD is slowly becoming the de facto way of writing code and the secrets of SCRUM or Kanban were revealed even to the programmers in the darkest corners of the cubicle world. Automated testing and test driven development (TDD) are some of the essential techniques Agile provided to us programmers. And a tool that comes with those methodologies is used to produce test code coverage, which is the topic of this article.
The article starts with a brief definition of code coverage and gets right into an example class, PHPUnit test and the results of a code coverage generation. They show both output options, the text-only output and the full HTML output with clickable links and visualization of the covered lines of code. There's also an example of generating the coverage inside an IDE (PHPStorm). The post finishes with a look at the myths of code coverage including: "100% covered is bug free" and that "gaming the system" is pretty easy.