docs: updated

Author: cap-Bernardito

README.md

@@ -146,6 +146,7 @@ Use multi-process parallel running to improve the build speed.
 Default number of concurrent runs: `os.cpus().length - 1`.
 
 > ℹ️ Parallelization can speedup your build significantly and is therefore **highly recommended**.
+> If a parallelization is enabled, the packages in `minimizerOptions` must be required via strings (`packageName` or `require.resolve(packageName)`). Read more in [`minimizerOptions`](#minimizerOptions)
 
 #### `Boolean`
 
@@ -297,6 +298,23 @@ module.exports = {
 The function index in the `minify` array corresponds to the options object with the same index in the `minimizerOptions` array.
 If you use `minimizerOptions` like object, all `minify` function accept it.
 
+> If a parallelization is enabled, the packages in `minimizerOptions` must be required via strings (`packageName` or `require.resolve(packageName)`). In this case, we shouldn't use `require`/`import`.
+
+```js
+module.exports = {
+  optimization: {
+    minimize: true,
+    minimizer: [
+      new CssMinimizerPlugin({
+        minimizerOptions: {
+          preset: require.resolve('cssnano-preset-simple'),
+        },
+      }),
+    ],
+  },
+};
+```
+
 #### `processorOptions`
 
 Type: `Object`

package-lock.json

@@ -69,6 +69,7 @@
     "copy-webpack-plugin": "^8.1.1",
     "cross-env": "^7.0.2",
     "css-loader": "^5.2.1",
+    "cssnano-preset-simple": "^2.0.0",
     "csso": "^4.0.3",
     "del": "^6.0.0",
     "del-cli": "^3.0.1",

package.json

@@ -25,6 +25,10 @@ exports[`when applied with "minimizerOptions" option matches snapshot for "parse
 
 exports[`when applied with "minimizerOptions" option matches snapshot for "parser" option with "String" value: index.sss 1`] = `"a{color:#000}"`;
 
+exports[`when applied with "minimizerOptions" option matches snapshot for "preset" option with require.resolve "String" value: default-preset 1`] = `"p{border:0 solid var(--test);border-radius:var(--test);border-width:1px}"`;
+
+exports[`when applied with "minimizerOptions" option matches snapshot for "preset" option with require.resolve "String" value: preset-simple 1`] = `"p{border-width:1px;border-radius:var(--test);border:0 solid var(--test)}"`;
+
 exports[`when applied with "minimizerOptions" option matches snapshot for "stringifier" option with "Function" value: entry.css 1`] = `"body  color:reda  color:#00f"`;
 
 exports[`when applied with "minimizerOptions" option matches snapshot for "stringifier" option with "String" value: entry.css 1`] = `"body  color:reda  color:#00f"`;

test/__snapshots__/minimizerOptions-option.test.js.snap

@@ -0,0 +1,5 @@
+p {
+  border: 1px solid var(--test);
+  border-radius: var(--test);
+  border-width: 0;
+}

test/fixtures/minimizerOptions/order.css

@@ -75,6 +75,58 @@ describe('when applied with "minimizerOptions" option', () => {
     });
   });
 
+  it('matches snapshot for "preset" option with require.resolve "String" value', () => {
+    const compiler = getCompiler({
+      entry: {
+        entry: `${__dirname}/fixtures/minimizerOptions/order.css`,
+      },
+    });
+    new CssMinimizerPlugin({
+      minimizerOptions: {
+        preset: 'default',
+      },
+    }).apply(compiler);
+
+    const compiler2 = getCompiler({
+      entry: {
+        entry: `${__dirname}/fixtures/minimizerOptions/order.css`,
+      },
+    });
+    new CssMinimizerPlugin({
+      minimizerOptions: {
+        preset: require.resolve('cssnano-preset-simple'),
+      },
+    }).apply(compiler2);
+
+    const result1 = compile(compiler).then((stats) => {
+      expect(stats.compilation.errors).toEqual([]);
+      expect(stats.compilation.warnings).toEqual([]);
+
+      for (const file in stats.compilation.assets) {
+        // eslint-disable-next-line no-continue
+        if (/\.js$/.test(file)) continue;
+        expect(readAsset(file, compiler, stats)).toMatchSnapshot(
+          `default-preset`
+        );
+      }
+    });
+
+    const result2 = compile(compiler2).then((stats) => {
+      expect(stats.compilation.errors).toEqual([]);
+      expect(stats.compilation.warnings).toEqual([]);
+
+      for (const file in stats.compilation.assets) {
+        // eslint-disable-next-line no-continue
+        if (/\.js$/.test(file)) continue;
+        expect(readAsset(file, compiler2, stats)).toMatchSnapshot(
+          `preset-simple`
+        );
+      }
+    });
+
+    return Promise.all([result1, result2]);
+  });
+
   it('matches snapshot for "mergeRules" option (enable [default])', () => {
     const compiler = getCompiler({
       entry: {