How does zephyr track files that are not included in code coverage at all?

[mkschreder]

Been looking at jobs responsible for coverage:

zephyr/.github/workflows/codecov.yaml

Line 95 in 69f7fd9

mv twister-out/coverage.info lcov.pre.info

One question: what about files that are not covered at all?

This is a very real problem that results in false sense of security because the files that are not included into any test at all are also not included into the coverage report. This means that the coverage report can say "90% coverage" but in reality many files are not included so the actual coverage can be much lower. To find these files, one has to compare full list of files in the repository with the list of files in the coverage.info file. I don't see that zephyr is doing that anywhere.

Do we need to add this?