feat(tests): add Stryker mutation testing to VS Code extension#602
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feat(tests): add Stryker mutation testing to VS Code extension#602
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- Install @stryker-mutator/core v9.6.1 as a devDependency
- Add stryker.config.mjs targeting compiled JS in out/src/ to avoid
a TypeScript recompile step per mutant:
- Mutates 7 core logic files (tokenEstimation, sessionParser,
maturityScoring, usageAnalysis, utils/*)
- Runs 9 explicit unit test files (no shell globs for cross-platform safety)
- coverageAnalysis: off with command runner (node:test built-in)
- concurrency: 2, timeoutMS: 15000
- Threshold break: 0 (informational during rollout)
- HTML report written to reports/mutation/report.html
- Add test:mutation npm script: compile-tests then npx stryker run
- Add mutation-testing CI job in ci.yml:
- Only runs on pull_request events (not push to main)
- Depends on build job (tests must pass first)
- continue-on-error: true to keep it non-blocking
- Hard cap at 20 minutes
- Uploads HTML report artifact (14-day retention)
- Add .stryker-tmp and reports/mutation/ to .gitignore
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…ssue Stryker by default copies only git-tracked files to its sandbox. Since \out/\ is gitignored, the compiled test files and vscode-shim were missing from the sandbox, causing every test command to hang until Stryker's per-mutant timeout was reached. Setting inPlace:true makes Stryker mutate the compiled JS files directly in the working directory (no sandbox), which works correctly since npm run compile-tests already runs before npx stryker run. Stryker still backs up the originals in .stryker-tmp before each mutation and restores them afterwards. Verified locally: html.js run completed in 5s with 0 timeouts. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…on-error Job-level continue-on-error keeps the CI workflow green but still marks the mutation-testing job check as FAILURE. Adding continue-on-error at the step level ensures the job itself succeeds even when Stryker times out, so the check shows SUCCESS and doesn't block PR merges. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Remove usageAnalysis.js (1905 lines) and maturityScoring.js (1212 lines) from the mutate list — together they generate ~5000+ mutations and push total run time well past the 20-minute CI timeout. Keep the focused utility files (tokenEstimation, sessionParser, dayKeys, errors, html) which produce a manageable ~800 mutations. Also increase concurrency 2→4 to cut run time roughly in half. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
- Replace coactions/setup-xvfb (abandoned, Node.js 20 only) with manual xvfb install+start to eliminate the Node.js deprecation warning - Add 'json' reporter to stryker.config.mjs so step summary has data - Add 'Publish mutation summary' step that writes a markdown table to GITHUB_STEP_SUMMARY from mutation.json (with fallback when missing) - Add if-no-files-found: ignore to mutation report upload so the step does not error when Stryker times out before writing the report Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Adds Stryker Mutator mutation testing to the VS Code extension to measure test suite quality beyond code coverage.
What changed
vscode-extension/stryker.config.mjs(new)commandtest runner (compatible with Node.js built-innode:test)out/src/— avoids a TypeScript recompile step per mutanttokenEstimation,sessionParser,maturityScoring,usageAnalysis, andutils/*coverageAnalysis: off,concurrency: 2,timeoutMS: 15000break: 0— informational during initial rollout, won't block mergingreports/mutation/report.htmlvscode-extension/package.json@stryker-mutator/core ^9.6.1devDependencytest:mutationscript:npm run compile-tests && npx stryker run.github/workflows/ci.ymlmutation-testingjob:buildjob (tests must pass first)continue-on-error: true— non-blocking during rollouttimeout-minutes: 20.gitignore.stryker-tmpandreports/mutation/How to run locally
Notes
extension.ts,webview/, andbackend/(Azure SDK) are excluded from this initial rollout.break: 0threshold means the job reports scores but never fails. Once baseline scores are known, raise the threshold.