Improve documentation for Code Coverage

Problem to solve

Our code coverage documentation is a bit confusing, and different facets are spread out on different pages.

• https://docs.gitlab.com/ee/ci/yaml/#coverage
• https://docs.gitlab.com/ee/ci/pipelines/settings.html#view-code-coverage-history
• https://docs.gitlab.com/ee/user/project/merge_requests/test_coverage_visualization.html

Some features (e.g. coverage check and coverage history) utilize the coverage keyword and other features (e.g. MR Diffs) utilize the artifacts:reports:cobertura keyword.

It can be confusing for users to determine which keyword they should use for which feature.

Proposal

Rework https://docs.gitlab.com/ee/user/project/merge_requests/test_coverage_visualization.html to be about all test coverage features with sections on the different configurations of coverage and their features.

We should also add Related topics sections to the CI/CD reference docs for coverage and artifacts:reports:cobertura.

Update (12/2024)

Files are now located at:

• https://docs.gitlab.com/ee/ci/testing/code_coverage.html
• https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization/
• https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization/cobertura.html
• https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization/jacoco.html

Who can address the issue

~"group::pipeline insights"

Other links/references