[Tracking] Coverage prototype

[valentinpalkovic]

RFC

#28397

Milestones

Use this space to document how the project will be split up. At project kickoff, at minimum we should have all the milestones split up, and emphasize which is must-have and which is nice-to-have. As we dig in, flesh out the detailed implementational tasks in each milestone.

Milestone 1: Spike

Beta Give feedback

1. Vitest: Create "Component Coverage" per story file #28628
   +0
2. Vitest|Storybook: Create communication channel to gather coverage information #28629
   +0
3. Storybook Coverage Viewer Addon - Create UI for Displaying Coverage Data #28631
   +0
4. Spawn Vitest in a subprocess (Coverage: Spawn in sub-process #28937)

Milestone 2: Benchmarking

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1. Benchmark istanbul vs v8
2. Benchmark happy-dom vs browser mode
3. Benchmark "Component Coverage" vs "Project Coverage"
4. Test: Coverage Differences between @storybook/test-runner and vitest

Milestone 3: Stretch goals

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1. [Feature Request]: File Selection: Show coverage for all relevant files #28630
   +0
2. Investigation: CSS Coverage
3. Pre-Build Coverage Report Generation

Nice to Have

Related issues that may be resolved by this project

Beta Give feedback

1. [Bug]: ComponentPath Resolution Fails with Import Maps in Storybook #28949
   +0
   
2. [Bug]: Failed to fetch dynamically imported module: http://localhost:3000/@id/@vitest/coverage-istanbul?import

Decision Records

Vocabulary

• Project Coverage: Comprehensive coverage of the component, including all tests from various stories and higher-level components that include the targeted component.
• Story Coverage: Coverage resulting only from the currently selected story (not all stories in one story file)
• Component Coverage: Coverage resulting from all stories of the currently selected story file

[greptile-apps]

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References

/.github/ISSUE_TEMPLATE/bug_report.yml
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/.github/workflows/stale.yml
/.github/workflows/triage.yml

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[cenfun]

I created a tool MCR that can generate coverage reports directly from V8. It does not require instrumenting source code like Istanbul.

• Preview reports https://cenfun.github.io/monocart-coverage-reports/
• CSS Coverage support https://cenfun.github.io/monocart-coverage-reports/css/index.html
• Example for Storybook https://github.com/cenfun/storybook-monocart-coverage

Not sure if it's useful but maybe an additional option.