coverage

When configuring with -DCOVERAGE:BOOL=ON compiled code will be instrumented when ran. Usually by running the tests but running code any way, such as by the main executable and manually doing things inside the program, will work.

Target coverage_report is also added. The target will build an HTML report based upon the lines of code ran at the point of generating.

Additionally target coverage_reset will be added. This target will reset all coverage counters in preparation for either running tests again or running code any other way.

Keep in mind counters are accumulative. If the counters are empty running the tests twice, provided your tests are deterministic, will result in all count events happening twice compared to running tests once. Generating a coverage report after may result into a rather confusing report when you expect lines being executed only x times but find out they have been executed 2x times.