• Measure the code coverage for your unit tests or tests written as simple applications with the main() method
• On-the-fly code coverage execution with no classes pre scanning phase
• Code coverage statistics for classes and packages
• 
• Line executions results right in the editor
• 
• Correct coverage information displayed for files edited after coverage statistics has been gathered

Learn more about the code coverage feature in the dedicated post on IntelliJ IDEA blog.