With an expressive language such as Ruby or Groovy and with modern test practices, 100% test coverage is readily achievable. But 100% coverage is meaningless without other supporting habits and practices. Over the last few years, we have taken dozens of projects to 100% coverage, and there are still plenty of things that can go wrong: We will look at examples of each of these problems (and others as well), and show how to prevent them from infecting your project. * Fragile Mocking * Incidental Coverage * The Ugly Mirror * Overspecification * Slow Tests * Underspecification * Shallow Tests * Invisible Code We will look at examples of each of these problems (and others as well), and show how to prevent them from infecting your project. Jason Rudolph is a Principal at Relevance, a leading consultancy and training organization specializing in Ruby, Rails, Groovy, and Grails, and integrating them into enterprise environments. Jason has more than nine years of experience in developing software solutions for domestic and international clients of all sizes, including start-ups, Dow 30 companies, and government organizations. Jason is the author of the highly-praised book, Getting Started with Grails, and speaks frequently at software conferences and user groups. Jason also contributes regularly to the open source community, both as an early committer to Grails, and also as a committer to the Streamlined framework and numerous other Ruby and Rails projects. Jason holds a degree in Computer Science from the University of Virginia.