1. Check that the commits tab of your pull request on Codecov.io matches with what you expect. Ensure that the parent and head commits have uploaded coverage to compare.
2. Review the coverage reports in the Build tab. Ensure that the coverage reports are a supported coverage report format.
3. Make sure your tests are idempotent and that they are all running.
4. Validate your codecov.yml file.
5. Check Unexpected Coverage Changes.