Where does Stryker put its HTML report?

With the default `html` reporter, at `reports/mutation/mutation.html`. It is a single self-contained file — the mutation-testing-elements web component with the results embedded — which makes it straightforward to publish.

How do I share it with the team?

Drag `reports/mutation/mutation.html` into Comma, or PATCH it to the API from CI. One URL, and comments anchor to the specific surviving mutants.

Does the interactive file tree still work?

Yes. Report HTML renders with scripts enabled inside a sandboxed iframe, so the file tree, the mutant filters and the annotated source view all behave the way they do locally.

How do I publish when Stryker fails the build on a low score?

Run the publish step with `if: always()` (GitHub Actions) or the equivalent. A run that fell under `thresholds.break` is the run somebody needs to look at.

Is mutation score worth tracking over time?

More than line coverage is. PATCH the same report id every run and each build appends a revision, so you can see whether a refactor actually removed assertions or just moved them.

Share a Stryker mutation report

Stryker's HTML report is the best-designed artifact in JavaScript testing: a file tree, a mutation score per directory, and source with every killed and surviving mutant marked inline. It is also a file at reports/mutation/mutation.html on a CI runner, and its usual fate is a number in a Slack message.

"Mutation score 61%." Nobody has ever fixed a test from that sentence.

Publish the file

npx stryker run

Drag reports/mutation/mutation.html into the app, or from CI:

npx stryker run || true

curl -fsS -X PATCH "https://commareports.com/api/v1/reports/$REPORT_ID" \
  -H "Authorization: Bearer $COMMA_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d "$(jq -n --rawfile html reports/mutation/mutation.html \
        --arg title "Mutation — $GITHUB_SHA" '{title: $title, html: $html}')"

Stryker exits non-zero below thresholds.break, so either tolerate the exit code on the run step or publish with if: always().

The report is self-contained — no assets folder to carry — so this is one of the easier artifacts to wire up.

Triage the survivors

A surviving mutant is a question: would we care if this behaviour changed? Half the time the honest answer is no, and that answer is worth writing down where the next person will see it.

Anchored threads on the mutant — "equivalent mutant, the branch is unreachable" — see commenting on HTML.
Revisions — one report id per package, one revision per run. A score that fell after a refactor is a diff you can point at in review.
Access per report — private, team, domain-gated, or named reviewers. See the sharing model.

Limits

Entry HTML: 5 MB. Stryker inlines the full results JSON, so a very large monorepo run can approach it — run per package and publish one report each.
60 requests/minute per token.

Try it

Comma is free — unlimited reports, unlimited commenters, unlimited revision history.

Publish a mutation report →

Share a Stryker mutation report

Publish the file

Triage the survivors

Limits

Try it

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