JaCoCo is quite a new maven plug-in that provides the JaCoCo runtime agent to your tests and allows basic report creation. Currently it supports instruction, branch, line, method and class coverage which is pretty enough you can expect from this kind of tool. Additionally, it can measure and report cyclomatic complexity for methods and summarize the complexity for classes and packages.
So if you want to have line number information included in the coverage reports or you want source code highlighting the class files of the test target must be compiled with debug information.
Note when it is used in conjuction with the maven-surefire-plugin or maven-failsafe-plugin you must not use a forkCount of 0 or set the forkMode to never as this would prevent the execution of the tests with the javaagent set and no coverage would be recorded. Read More