Comma

Test reporter

A test reporter is the part of a test runner that turns its events into output. The runner executes tests and decides what passed. The reporter listens (run started, test finished, run complete) and writes the result somewhere: the terminal, a JUnit XML file, JSON, or an HTML report.

Reporters are pluggable, so the same run can produce several outputs. That's the normal setup, not an advanced one.

The usual three

Reporter type Who reads it Example output
Console Whoever is watching the job Dots, a list, a summary line
JUnit XML The CI system, the code host junit.xml for test tabs and PR checks
HTML Reviewers, QA, PMs, the on-call report.html or a playwright-report/ folder

JSON reporters (--json in Jest, json in Playwright) are a fourth, mostly for your own scripts and dashboards.

How each runner configures them

Jest — a reporters array. Setting it replaces the defaults, so keep "default":

reporters: ["default", ["jest-junit", { outputDirectory: "reports" }]];

Vitest — repeat --reporter, or set reporters in the config:

vitest run --reporter=default --reporter=junit --outputFile.junit=junit.xml

Playwright — a list of [name, options] tuples:

reporter: [
  ["list"],
  ["junit", { outputFile: "results/junit.xml" }],
  ["html", { open: "never" }],
],

pytest — flags combine: --junitxml=junit.xml is built in, --html=report.html --self-contained-html comes from the pytest-html plugin.

Mocha and Cypress — --reporter takes one reporter. To get more, wrap them with mocha-multi-reporters or cypress-multi-reporters.

Go — go test has no reporter plugins, only -json. Tools like gotestsum --junitfile junit.xml read that stream and write the other formats.

.NET — loggers: dotnet test --logger trx --logger "junit" (the second one from the JunitXml.TestLogger package).

Where reporters go wrong

  • The defaults disappear. Jest and Playwright replace the default reporter when you configure one. The terminal goes quiet.
  • The CLI overrides the config. A --reporter or --reporters flag in a CI script replaces the configured list rather than adding to it. See Jest HTML report not generated.
  • The HTML report isn't one file. Playwright, Allure, Vitest and jest-html-reporters write a folder, and the page loads its data from it. Send only the HTML and it opens blank. See self-contained HTML.
  • The report never leaves CI. It's uploaded as a build artifact, behind a login, and expires under retention.

The HTML report is the one people read

JUnit XML tells CI a test failed. The HTML report shows why: the assertion diff, the screenshot, the trace, the timing. It's also the output most likely to be stuck in a zip. Publishing it to a link, with each run as a revision of the same page, turns it into something a team can discuss. Comma does that with one curl from CI (publish from CI), and the JUnit XML viewer turns a junit.xml into an HTML report when the runner doesn't have one.

Try it

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

Publish a test report →

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