index.js

'use strict';
const path = require('path');
const execa = require('execa');
const hasYarn = require('has-yarn');
const readPkgUp = require('read-pkg-up');
const writePkg = require('write-pkg');

const DEFAULT_TEST_SCRIPT = 'echo "Error: no test specified" && exit 1';

module.exports = async (options = {}) => {
	const packageResult = readPkgUp.sync({
		cwd: options.cwd,
		normalize: false
	}) || {};
	const packageJson = packageResult.package || {};
	const packagePath = packageResult.path || path.resolve(options.cwd || process.cwd(), 'package.json');
	const packageCwd = path.dirname(packagePath);
	const next = Boolean(options.next);
	const args = options.args || [];
	const cmd = 'ava' + (args.length > 0 ? ' ' + args.join(' ') : '');

	packageJson.scripts = packageJson.scripts ? packageJson.scripts : {};

	const s = packageJson.scripts;
	if (s.test && s.test !== DEFAULT_TEST_SCRIPT) {
		s.test = s.test.replace(/\bnode (test\/)?test\.js\b/, cmd);

		if (!/\bava\b/.test(s.test)) {
			s.test += ` && ${cmd}`;
		}
	} else {
		s.test = cmd;
	}

	writePkg.sync(packagePath, packageJson, {normalize: false});

	if (options.skipInstall) {
		return;
	}

	const avaTag = next ? 'ava@next' : 'ava';

	if (hasYarn(packageCwd)) {
		const yarnArguments = ['add', avaTag, '--dev', '--ignore-workspace-root-check', 'ava'];
		if (next) {
			yarnArguments.push('--exact');
		}

		try {
			await execa('yarn', yarnArguments, {
				cwd: packageCwd,
				stdio: 'inherit'
			});
		} catch (error) {
			if (error.code === 'ENOENT') {
				console.error('This project uses Yarn but you don\'t seem to have Yarn installed.\nRun `npm install --global yarn` to install it.');
				return;
			}

			throw error;
		}

		return;
	}

	const npmArguments = ['install', '--save-dev'];
	if (next) {
		npmArguments.push('--save-exact');
	}

	npmArguments.push(avaTag);

	await execa('npm', npmArguments, {
		cwd: packageCwd,
		stdio: 'inherit'
	});
};