Output JSON structured logs from cypress for machine readable test logs

cypress.json

{
  "reporter": "structured-log.js",
  "quiet": true
}

structured-log.js

const Mocha = require('mocha');
const {
  EVENT_RUN_BEGIN,
  EVENT_RUN_END,
  EVENT_TEST_FAIL,
  EVENT_TEST_PASS,
  EVENT_TEST_RETRY,
  EVENT_TEST_PENDING,
} = Mocha.Runner.constants;

class StructuredLog {
  constructor(runner) {
    const stats = runner.stats;
    runner.once(EVENT_RUN_BEGIN, function () {
      writeEvent({ type: 'run:start', total: runner.total });
    });

    runner.on(EVENT_TEST_PASS, function (test) {
      writeEvent({ type: 'test:pass', ...clean(test) });
    });

    runner.on(EVENT_TEST_RETRY, function (test) {
      writeEvent({ type: 'test:retry', ...clean(test) });
    });

    runner.on(EVENT_TEST_PENDING, function (test) {
      writeEvent({ type: 'test:skipped', ...clean(test) });
    });

    runner.on(EVENT_TEST_FAIL, function (test) {
      writeEvent({ type: 'test:fail', ...clean(test) });
    });

    runner.once(EVENT_RUN_END, function () {
      writeEvent({ type: 'run:end', ...stats });
    });
  }
}

function writeEvent(event) {
  process.stdout.write(JSON.stringify(event) + '\n');
}

function clean(test) {
  return {
    title: test.title,
    fullTitle: typeof test.fullTitle === 'function' ? test.fullTitle() : test.fullTitle,
    file: test.invocationDetails && test.invocationDetails.relativeFile,
    duration: test.duration,
    currentRetry: typeof test.currentRetry === 'function' ? test.currentRetry() : test.currentRetry,
    retries: typeof test.retries === 'function' ? test.retries() : test.retries,
    speed: test.speed,
    error: test.err
      ? {
          message: test.err.message,
          stack: test.err.sourceMappedStack || test.err.stack,
        }
      : undefined,
  };
}

module.exports = StructuredLog;