TestQA/node_modules/webpack-cli/lib/migrate/index.js

const jscodeshift = require("jscodeshift");
const pEachSeries = require("p-each-series");
const PLazy = require("p-lazy");

const loadersTransform = require("./loaders/loaders");
const resolveTransform = require("./resolve/resolve");
const removeJsonLoaderTransform = require("./removeJsonLoader/removeJsonLoader");
const uglifyJsPluginTransform = require("./uglifyJsPlugin/uglifyJsPlugin");
const loaderOptionsPluginTransform = require("./loaderOptionsPlugin/loaderOptionsPlugin");
const bannerPluginTransform = require("./bannerPlugin/bannerPlugin");
const extractTextPluginTransform = require("./extractTextPlugin/extractTextPlugin");
const noEmitOnErrorsPluginTransform = require("./noEmitOnErrorsPlugin/noEmitOnErrorsPlugin");
const removeDeprecatedPluginsTransform = require("./removeDeprecatedPlugins/removeDeprecatedPlugins");

const transformsObject = {
	loadersTransform,
	resolveTransform,
	removeJsonLoaderTransform,
	uglifyJsPluginTransform,
	loaderOptionsPluginTransform,
	bannerPluginTransform,
	extractTextPluginTransform,
	noEmitOnErrorsPluginTransform,
	removeDeprecatedPluginsTransform
};

const transformations = Object.keys(transformsObject).reduce((res, key) => {
	res[key] = (ast, source) =>
		transformSingleAST(ast, source, transformsObject[key]);
	return res;
}, {});

function transformSingleAST(ast, source, transformFunction) {
	return new PLazy((resolve, reject) => {
		setTimeout(_ => {
			try {
				resolve(transformFunction(jscodeshift, ast, source));
			} catch (err) {
				reject(err);
			}
		}, 0);
	});
}

/**
 *
 * Transforms a given piece of source code by applying selected transformations to the AST.
 * By default, transforms a webpack version 1 configuration file into a webpack version 2
 * configuration file.
 *
 * @param {String} source - source file contents
 * @param {Function[]} [transforms] - List of transformation functions, defined in the
 * order to apply them in. By default, all defined transformations.
 * @param {Object} [options] - recast formatting options
 * @returns {String} source — transformed source code
 */

function transform(source, transforms, options) {
	const ast = jscodeshift(source);
	const recastOptions = Object.assign(
		{
			quote: "single"
		},
		options
	);
	transforms =
		transforms || Object.keys(transformations).map(k => transformations[k]);
	return pEachSeries(transforms, f => f(ast, source))
		.then(_ => {
			return ast.toSource(recastOptions);
		})
		.catch(err => {
			console.error(err);
		});
}

module.exports = {
	transform,
	transformSingleAST,
	transformations
};