Unknown annotations in Azure DevOps Pull Request files tab

I was reviewing a pull request in our Azure DevOps instance and I noticed that in the Files tab some lines of code were annotated with flags, checkmarks and exclamation marks (see screenshot). I wasn't able to figure out what they mean. Hovering over them didn't display a hint balloon. Does anyone know?

Solution

Once you have configured a pipeline that collects and publishes code coverage, it posts a code coverage status when a pull request is raised. By default, the server checks for atleast 70% of changed lines being covered by tests.

In the changed files view of a pull request, lines that are changed are also annotated with coverage indicators to show whether those lines are covered. Check Code coverage for pull requests for details.