When code compiled for test coverage is executed, test coverage data is written to a binary results file called pli.tci in the current working directory. Test coverage data from multiple runs and different programs will all be accumulated in the same file. To start a fresh set of test coverage runs, delete or move the pli.tci file.
Running a program in test coverage mode uses significantly more resources than running the same program without test coverage enabled. As a result, we recommend that you use test coverage only in development systems; we recommend that you do not use test coverage in production systems.