/* eslint-disable no-console */

const { fork } = require('child_process');

const chokidar = require('chokidar');

const util = require('util');

const glob = util.promisify(require('glob'));

const chalk = require('chalk');

const _ = require('lodash');

console.log(chalk.cyan('Performing initial set up'));

const showErrors = process.argv.includes('showErrors');

let watcher;

let busy = false;

let pendingTests = [];

// all unit test files

const allUnitTests = glob.sync('{src,script,test}/**/*.unit.spec.js?(x)');

function runMochaTests(tests) {

// fork mocha into a separate process

const forked = fork('./script/mocha.js');

return new Promise((fulfill, reject) => {

// send the mocha process the tests to run

forked.send({

tests,

showErrors,

});

forked.on('message', ({ error, requiredFiles, unitTestsForSrc }) => {

if (error) {

// mocha runner returned an error

reject(error);

} else {

// mocha runner returend a list of files it required and a map of unit tests to source files

fulfill({ requiredFiles, unitTestsForSrc });

}

// kill mocha

forked.kill('SIGHUP');

});

});

}

// runs array of test files passed in or all tests if no value provided

async function runUnitTests(unitTests = allUnitTests) {

if (busy) {

pendingTests = _.union(pendingTests, unitTests);

return;

}

console.log(chalk.cyan(`Running ${unitTests.length} unit test files`));

busy = true;

let unitTestsForSrc;

let requiredFiles;

try {

// eslint-disable-next-line no-undef

({ requiredFiles, unitTestsForSrc } = await runMochaTests(unitTests));

} catch (e) {

if (!watcher) {

// mocha errored before setting up watcher; exit process

console.log(chalk.red('Mocha failed. Fix error and restart watch'));

process.exit(1);

} else {

// mocha errored after setting up watcher; continue watching for changes

console.log(chalk.red('Mocha failed. Fix error'));

}

}

busy = false;

// changes were detected during a test run; run these tests and clear the queue

if (pendingTests.length > 0) {

busy = false;

process.nextTick(() => {

runUnitTests(pendingTests);

pendingTests = [];

});

console.log(chalk.yellow('Changes detected during last run.'));

console.log(chalk.yellow('======'));

return;

}

console.log(chalk.yellow('Watching for changes'));

console.log(chalk.yellow('======\n\n'));

// watcher is only created once- if new files are added, then watcher must be restarted

if (!watcher) {

// start watcher with the files that mocha imported

watcher = chokidar.watch(requiredFiles).on('change', file => {

// if a unit test is updated just run that unit test

if (file.includes('.unit.spec')) {

runUnitTests([file]);

}

// if change is from a src file, run unit tests that import that src file

if (file.includes('src') && unitTestsForSrc[file]) {

runUnitTests(unitTestsForSrc[file]);

} else {

// if no unit tests import src file, run all unit tests

runUnitTests();

}

});

}

}

runUnitTests();