Adding files match with paths argument into coverage list

I discovered that:
- The coverage option (`--cov` or `coverage=true`) does coverage only the source file, but does not coverage other modules required by the source.
- The option `-p` or `--paths` has not been used anywhere in your code.

In this PR, I make the files that match the paths parameter include in coverage report, which I think it could be useful. Please review.