Convert mocha test list output to pure JSON

mocha-list-tests.js

/**
 * @file Workaround (conversion script) to address lack of proper mocha JSON output.
 *
 * @see https://gist.github.com/Domiii/ff89e1427ee51193721abdbb08842e58
 * @see https://stackoverflow.com/questions/41380137/list-all-mocha-tests-without-executing-them/68829700#68829700
 */

const fs = require('fs');
const path = require('path');

const inFile = process.argv[2];
const outFile = process.argv[3] || path.resolve(path.dirname(inFile), 'testList.json');

if (!inFile) {
  throw new Error(`First argument must be a file containing test output from a dry-run with the JSON formatter.`);
}

console.log(`Reading inFile ${inFile}...`);

const text = fs.readFileSync(inFile).toString();
/** @type {Array} */
const jsonObjectStrings = getJsonObjects(text) || [];

// console.debug(text.length, text.substring(0, 300));

const jsonObjects = jsonObjectStrings.map((s) => {
  try {
    const obj = JSON.parse(s);
    return [null, obj];
  }
  catch (err) {
    return [err, null, s];
  }
});

const objects = jsonObjects.filter(([, obj]) => !!obj);
// const nObj = objects.length;
const parseErrors = jsonObjects.filter(([err]) => !!err);
const nErr = parseErrors.length;
console.log(`Found ${jsonObjects.length} JSON objects in file with ${nErr} parse errors.\nWriting results to file "${outFile}"...`);

const finalJsonOutput = `[\n${objects
  .map(([, obj]) => JSON.stringify(obj, null, 2))
  .join(',\n')}
]`;
for (const [err, obj] of jsonObjects) {
  if (!obj) {
    continue;
  }
  fs.writeFileSync(outFile, finalJsonOutput);
}

console.log('  Finished writing file.');

if (nErr) {
  console.error(`\n\n${nErr} parse errors encountered:\n ${parseErrors.map(([err, , s], i) => `${i + 1}. ${err.message} (${s.substring(0, 100)})`)
      .join('\n ')
    }`);
}


// ###########################################################################
// utilities
// ###########################################################################

function getJsonObjects(s) {
  const re = /(\n\{(?:.|\n)*?\n\})/g;
  return s.match(re);
  // (() => {
  //   var text = '\n{a\n}\n{\n\nb\n}';
  //   console.log(text.match(re));
  // })();
}