feat: accept semver compatible postcss AST (#1049)

Author: jquense

package-lock.json

@@ -54,7 +54,8 @@
     "postcss-modules-scope": "^2.1.1",
     "postcss-modules-values": "^3.0.0",
     "postcss-value-parser": "^4.0.2",
-    "schema-utils": "^2.6.0"
+    "schema-utils": "^2.6.0",
+    "semver": "^6.3.0"
   },
   "devDependencies": {
     "@babel/cli": "^7.7.7",

package.json

@@ -2,24 +2,24 @@
   MIT License http://www.opensource.org/licenses/mit-license.php
   Author Tobias Koppers @sokra
 */
-import validateOptions from 'schema-utils';
+import { getOptions, isUrlRequest } from 'loader-utils';
 import postcss from 'postcss';
 import postcssPkg from 'postcss/package.json';
+import validateOptions from 'schema-utils';
+import { satisfies } from 'semver';
 
-import { getOptions, isUrlRequest } from 'loader-utils';
-
+import CssSyntaxError from './CssSyntaxError';
+import Warning from './Warning';
 import schema from './options.json';
-import { importParser, icssParser, urlParser } from './plugins';
+import { icssParser, importParser, urlParser } from './plugins';
 import {
-  normalizeSourceMap,
-  getModulesPlugins,
+  getExportCode,
   getFilter,
   getImportCode,
   getModuleCode,
-  getExportCode,
+  getModulesPlugins,
+  normalizeSourceMap,
 } from './utils';
-import Warning from './Warning';
-import CssSyntaxError from './CssSyntaxError';
 
 export default function loader(content, map, meta) {
   const options = getOptions(this) || {};
@@ -63,7 +63,11 @@ export default function loader(content, map, meta) {
   if (meta) {
     const { ast } = meta;
 
-    if (ast && ast.type === 'postcss' && ast.version === postcssPkg.version) {
+    if (
+      ast &&
+      ast.type === 'postcss' &&
+      satisfies(ast.version, `^${postcssPkg.version}`)
+    ) {
       // eslint-disable-next-line no-param-reassign
       content = ast.root;
     }

src/index.js

@@ -0,0 +1,27 @@
+import postcss from 'postcss';
+import postcssPresetEnv from 'postcss-preset-env';
+import postcssPkg from 'postcss/package.json';
+import semver from 'semver';
+
+const incomingVersion = semver.inc(postcssPkg.version, 'minor');
+
+export default function astLoader(content) {
+  const callback = this.async();
+
+  const { spy = jest.fn() } = this.query;
+
+  postcss([postcssPresetEnv({ stage: 0 })])
+    .process(content)
+    .then(({ css, map, root, messages }) => {
+      const ast = {
+        type: 'postcss',
+        version: incomingVersion,
+      };
+
+      Object.defineProperty(ast, 'root', {
+        get: spy.mockReturnValue(root),
+      });
+
+      callback(null, css, map, { ast, messages });
+    });
+}

test/helpers/ast-loader.js

@@ -1,7 +1,5 @@
 import path from 'path';
 
-import postcssPresetEnv from 'postcss-preset-env';
-
 import { version } from 'webpack';
 
 import {
@@ -129,6 +127,7 @@ describe('loader', () => {
   });
 
   it('should reuse `ast` from "postcss-loader"', async () => {
+    const spy = jest.fn();
     const compiler = getCompiler(
       './postcss-present-env/source.js',
       {},
@@ -143,8 +142,8 @@ describe('loader', () => {
                   options: { importLoaders: 1 },
                 },
                 {
-                  loader: 'postcss-loader',
-                  options: { plugins: () => [postcssPresetEnv({ stage: 0 })] },
+                  loader: require.resolve('./helpers/ast-loader'),
+                  options: { spy },
                 },
               ],
             },
@@ -159,6 +158,8 @@ describe('loader', () => {
     );
     const stats = await compile(compiler);
 
+    expect(spy).toHaveBeenCalledTimes(1);
+
     expect(
       getModuleSource('./postcss-present-env/source.css', stats)
     ).toMatchSnapshot('module');