Problem: unexpected coverage changes

[sevein]

Describe the bug

Some pull requests are not building successfully because codecov is reporting negative coverage, i.e. unexpected coverage changes. It's easy to find "indirect changes" via the Codecov web interface but it's not always easy to fix them.

This issue aims to be used track areas of the code where this is happening.

• filenotify (fixed in Block in filePoller.Close until loop is finished #879)
• sftp (follow link for more details)
• watcher (follow link for more details)

Also:

• We can configure codecov status checks with a threshold allowing a certain number of lines to transition from covered to uncovered without reporting a negative patch coverage result.

To Reproduce

• Submit a pull request
• Watch codecov/project fail
• Open pull request on Codecov, e.g. https://app.codecov.io/gh/artefactual-sdps/enduro/pull/891/indirect-changes

Additional context

• Use [skip codecov] to skip codecov.
• https://docs.codecov.com/docs/unexpected-coverage-changes