fix: compatibility with webpack@5 (#437)

Author: cap-Bernardito

src/index.js

@@ -1,4 +1,5 @@
 import path from 'path';
+import Module from 'module';
 
 import { getOptions } from 'loader-utils';
 import validateOptions from 'schema-utils';
@@ -11,6 +12,23 @@ import SyntaxError from './Error';
 import parseOptions from './options';
 import schema from './options.json';
 
+const parentModule = module;
+
+function exec(code, loaderContext) {
+  const { resource, context } = loaderContext;
+
+  const module = new Module(resource, parentModule);
+
+  // eslint-disable-next-line no-underscore-dangle
+  module.paths = Module._nodeModulePaths(context);
+  module.filename = resource;
+
+  // eslint-disable-next-line no-underscore-dangle
+  module._compile(code, resource);
+
+  return module.exports;
+}
+
 /**
  * **PostCSS Loader**
  *
@@ -113,7 +131,7 @@ export default function loader(content, sourceMap, meta = {}) {
       // https://webpack.js.org/api/loaders/#deprecated-context-properties
       if (postcssOptions.parser === 'postcss-js') {
         // eslint-disable-next-line no-param-reassign
-        content = this.exec(content, this.resource);
+        content = exec(content, this);
       }
 
       if (typeof postcssOptions.parser === 'string') {
@@ -135,7 +153,7 @@ export default function loader(content, sourceMap, meta = {}) {
       // https://webpack.js.org/api/loaders/#deprecated-context-properties
       if (config.exec) {
         // eslint-disable-next-line no-param-reassign
-        content = this.exec(content, this.resource);
+        content = exec(content, this);
       }
 
       if (options.sourceMap && typeof sourceMap === 'string') {

test/options/__snapshots__/exec.test.js.snap

@@ -1,5 +1,11 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`Options Exec should work Exec - {Boolean}: css 1`] = `"module.exports = \\"a {\\\\n    color: green\\\\n}\\""`;
+
+exports[`Options Exec should work Exec - {Boolean}: errors 1`] = `Array []`;
+
+exports[`Options Exec should work Exec - {Boolean}: warnings 1`] = `Array []`;
+
 exports[`Options Exec should work JSS - {String}: css 1`] = `
 "module.exports = { a: { color: 'yellow' } }
 "

test/options/exec.test.js

@@ -9,35 +9,34 @@ import {
 } from '../helpers/index';
 
 describe('Options Exec', () => {
-  // Todo loaderContext.exec is deprecated and removed in webpack 5
-  // it('should work Exec - {Boolean}', async () => {
-  //   const compiler = getCompiler(
-  //     './jss/exec/index.js',
-  //     {},
-  //     {
-  //       module: {
-  //         rules: [
-  //           {
-  //             test: /style\.(exec\.js|js)$/i,
-  //             use: [
-  //               {
-  //                 loader: path.resolve(__dirname, '../../src'),
-  //                 options: { exec: true },
-  //               },
-  //             ],
-  //           },
-  //         ],
-  //       },
-  //     }
-  //   );
-  //   const stats = await compile(compiler);
-  //
-  //   const codeFromBundle = getCodeFromBundle('style.exec.js', stats);
-  //
-  //   expect(codeFromBundle.css).toMatchSnapshot('css');
-  //   expect(getWarnings(stats)).toMatchSnapshot('warnings');
-  //   expect(getErrors(stats)).toMatchSnapshot('errors');
-  // });
+  it('should work Exec - {Boolean}', async () => {
+    const compiler = getCompiler(
+      './jss/exec/index.js',
+      {},
+      {
+        module: {
+          rules: [
+            {
+              test: /style\.(exec\.js|js)$/i,
+              use: [
+                {
+                  loader: path.resolve(__dirname, '../../src'),
+                  options: { exec: true },
+                },
+              ],
+            },
+          ],
+        },
+      }
+    );
+    const stats = await compile(compiler);
+
+    const codeFromBundle = getCodeFromBundle('style.exec.js', stats);
+
+    expect(codeFromBundle.css).toMatchSnapshot('css');
+    expect(getWarnings(stats)).toMatchSnapshot('warnings');
+    expect(getErrors(stats)).toMatchSnapshot('errors');
+  });
 
   it('should work JSS - {String}', async () => {
     const compiler = getCompiler(