node:testでJSON出力するreporterサンプル

reporter.js

module.exports = async function * customReporter(source) {

  let roots = []
  let currentSuite = null;

  function startTest(event) {
    const parent = currentSuite;
    currentSuite = {
      name: event.data.name,
      nesting: event.data.nesting,
      parent,
      children: [],
    }
    if (parent) {
      parent.children.push(currentSuite);
    } else {
      roots.push(currentSuite);
    }
  }
  
  for await (const event of source) {
    switch (event.type) {
      case 'test:start':
        startTest(event);
        break;
      case 'test:pass':
      case 'test:fail':
        if(!currentSuite) {
          startTest(event);
        }
        if (currentSuite?.name !== event.data.name ||
          currentSuite?.nesting !== event.data.nesting) {
          startTest(event);
        }
        currentSuite.status = event.type
        if (currentSuite?.nesting === event.data.nesting) {
          currentSuite = currentSuite.parent;
        }
        break;
    }
  }

  // console.dir(roots, { depth: null })
  const json = JSON.stringify(roots, (key, value) => {
    return key === "parent" ? value?.name: value
  }, 2)
  yield json
};