Does flutter test produce an HTML report?

No. `flutter test --coverage` writes `coverage/lcov.info`, which is a machine format, and test results go to the terminal or to `--machine` JSON. HTML comes from converting: `genhtml` for the coverage report, and a JUnit converter for the results if your CI wants them.

How do I turn Flutter coverage into an HTML report?

Run `flutter test --coverage`, then `genhtml coverage/lcov.info -o coverage/html` (genhtml ships with lcov, installable via Homebrew or apt). That produces a browsable directory of annotated Dart source, which is the artifact worth sharing.

How do I share it with the team?

Drop the generated `coverage/html/` folder into Comma, or publish it from CI. The entry page becomes the report body, the per-file pages upload alongside it with relative references rewritten, and reviewers open a URL.

Why does my coverage exclude generated files?

It usually shouldn't include them. Filter before converting — `lcov --remove coverage/lcov.info '*.g.dart' '*.freezed.dart' -o coverage/filtered.info` — otherwise generated serialization code dominates the numbers and hides the code you actually wrote.

Can I keep the same URL across runs?

Yes. Save the report id as a CI variable and PATCH it every run. Each run appends a revision at the same address, so diffing two revisions shows which lines changed coverage rather than a percentage drifting.

Share a Flutter test and coverage report

flutter test --coverage gives you coverage/lcov.info. That is not a report — it is a machine format that a tool is supposed to read. Yet it is routinely what gets uploaded as a CI artifact and then never opened, since opening it accomplishes nothing.

The readable artifact is one conversion away.

Convert it

flutter test --coverage || true

# strip generated code first — it dominates the numbers otherwise
lcov --remove coverage/lcov.info \
  '*.g.dart' '*.freezed.dart' '*.mocks.dart' \
  -o coverage/filtered.info

genhtml coverage/filtered.info -o coverage/html
# → coverage/html/index.html

genhtml ships with lcov (brew install lcov, apt install lcov). The filtering step is not optional in practice: a Flutter project with json_serializable and freezed generates a great deal of Dart, and including it produces a coverage number that means nothing.

The output is a directory — index.html, a page per source file, plus stylesheets — so publish the folder.

Drop the folder in

Drag coverage/html/ (or a zip) into Comma:

index.html becomes the report body — the page carrying the comment layer.
The per-file pages and CSS upload alongside it, with relative references rewritten, so the drill-down from summary to directory to annotated Dart resolves.
Scripts run inside a sandboxed iframe (allow-scripts, no allow-same-origin), so the sortable columns keep working.

From CI

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 coverage/html/index.html \
        --arg title "Coverage — $(git rev-parse --short HEAD)" \
        '{title: $title, html: $html}')"

The API is JSON-only, so the per-file pages go up through POST /api/v1/reports/$REPORT_ID/assets as base64 — one call per file, worth scripting once. See the API reference.

The || true on the test command and an if: always() on the step keep the publish alive when a test fails, which is when the report matters. Use a scoped token (reports:write) from CI secrets and PATCH a saved report id. See publishing from CI.

Test results, if you want them too

flutter test --machine emits a JSON event stream that JUnit converters consume, which is the route if your pipeline wants a results view alongside coverage:

flutter test --machine | tojunit --output junit.xml

See share a JUnit report. For integration tests driving a real device, the shape is closer to the Android and Xcode reports.

What the URL changes

The PR links the coverage. Reviewers click instead of running the suite and genhtml locally.
Review lands on the widget. Select the uncovered branch, leave a thread — "this is the error state, it has no test" — and it stays anchored across runs. See commenting on HTML.
Revision diffs beat the percentage, especially in Flutter where the number swings whenever the generated-code filter changes.

Who can see it

The coverage report contains your Dart source. Access is per report — private, your team, any signed-in user with the link, or public — and team or private is the right default for a private repo. Domain-gating is Enterprise. See sharing & access control.

Limits

Entry HTML: 5 MB. Assets: 25 MB per file, 250 MB and 500 files total. A large app can exceed 500 source pages — publish the feature directory under review rather than the whole tree.
Scripts run, sandboxed — no same-origin access.
60 requests/minute per token.

Try it

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

Publish a coverage report →