How do I get an HTML coverage report from Deno?

`deno test --coverage=cov_profile`, then `deno coverage cov_profile --lcov --output=cov.lcov`, then `genhtml cov.lcov -o coverage-html`. Publish the folder to Comma and the drill-down works at the URL.

Does Deno have a built-in HTML coverage output?

`deno coverage --html` writes a static HTML tree directly, which skips the lcov step. Either path ends in a folder whose `index.html` is the entry page.

How do I publish results rather than coverage?

`deno test --reporter=junit` emits JUnit XML. Convert it with a tool like `junit2html` and publish the resulting file — or publish both, results as the report body and coverage as a second report.

Can I publish from a failing run?

Yes, and you should. Capture the exit code, publish, then re-raise it — otherwise the only runs that get a link are the green ones nobody needs to look at.

Can teammates comment on a specific uncovered file?

Yes. Threads anchor to the rendered content, so "this branch is unreachable, it's a type guard" stays on that file instead of in a channel.

Share a Deno test report

Deno ships a test runner, a coverage tool and a formatter in the binary, which removes most of the setup other ecosystems spend a week on. It does not remove the last step, which is the one that actually costs a team time: getting the result in front of someone who is not sitting at a terminal.

Coverage, two ways

The short one:

deno test --coverage=cov_profile
deno coverage cov_profile --html      # → cov_profile/html/

The lcov one, if you already have tooling that speaks it:

deno coverage cov_profile --lcov --output=cov.lcov
genhtml cov.lcov -o coverage-html

Either way you end with a folder: an index listing files by coverage, and a page per file with the uncovered lines marked. That structure is the whole point — coverage is read by clicking down into the file you suspect, which is the one thing a percentage in a CI log cannot support.

Results

deno test --reporter=junit --junit-path=./junit.xml
npx junit2html junit.xml results.html

Publish it

Drag the coverage folder (or a zip of it) into Comma:

index.html becomes the report body.
Per-file pages and the stylesheet upload alongside it, with relative references rewritten to the uploaded copies, so the drill-down resolves — which is the step that fails when the folder is zipped and emailed, because a file:// origin breaks the relative fetches. See coverage report links broken.
Scripts run inside a sandboxed iframe (allow-scripts, no allow-same-origin).

From CI

deno test --coverage=cov_profile || FAILED=1
deno coverage cov_profile --html

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 cov_profile/html/index.html \
        --arg t "Coverage — $(git rev-parse --short HEAD)" '{title: $t, html: $html}')"

exit "${FAILED:-0}"

Publish first, fail second. Supporting pages go up through POST /api/v1/reports/$REPORT_ID/assets as base64 — see the API reference and publishing from CI.

One link, a revision per run

PATCHing a saved report id keeps the URL constant while the content tracks the default branch. Each publish appends a revision, so a coverage drop is visible as a diff between two runs instead of as a number somebody remembers being higher. Unlike a CI artifact, it does not expire — see expired CI artifacts.

Who can see it

Per report: private, your team, anyone signed in at your domain, or anyone with the link. Coverage output contains source — team access is the usual setting. See sharing & access control.

Limits

Entry HTML: 5 MB. Assets: 25 MB per file, 250 MB and 500 files total. A large module tree can exceed 500 files — publish the index plus the directories under active work.
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 →