docs: note about source maps in singleton mode (#415)

test/manual/src/component.module.css

@@ -0,0 +1,20 @@
+@value v-red: red;
+@value v-green: green;
+@value v-blue: blue;
+
+.module-red {
+  color: v-red;
+}
+
+.module-green {
+  color: v-green;
+}
+
+.module-blue {
+  color: v-blue;
+}
+
+.module-background {
+  height: 1200px;
+  background: url('./logo.png') center no-repeat;
+}

test/manual/src/index.js

@@ -2,10 +2,46 @@
 
 import './style.css';
 import './other-style.scss';
+import styles from './component.module.css';
 import styleLazy from './style.lazy.css';
 import otherStyleLazy from './other-style.lazy.scss';
 import './style.link.css';
 import './custom-square';
 
 styleLazy.use();
 otherStyleLazy.use();
+
+const articleElement = document.createElement('article');
+const h3Element = document.createElement('h3');
+const h3TextNode = document.createTextNode('CSS modules');
+
+const divElement1 = document.createElement('div');
+const divElement1Content = document.createTextNode('Red');
+
+divElement1.className = styles['module-red'];
+divElement1.appendChild(divElement1Content);
+
+const divElement2 = document.createElement('div');
+const divElement2Content = document.createTextNode('Green');
+
+divElement2.className = styles['module-green'];
+divElement2.appendChild(divElement2Content);
+
+const divElement3 = document.createElement('div');
+const divElement3Content = document.createTextNode('Blue');
+
+divElement3.className = styles['module-blue'];
+divElement3.appendChild(divElement3Content);
+
+const divElement4 = document.createElement('div');
+
+divElement4.className = styles['module-background'];
+
+h3Element.appendChild(h3TextNode);
+articleElement.appendChild(h3Element);
+articleElement.appendChild(divElement1);
+articleElement.appendChild(divElement2);
+articleElement.appendChild(divElement3);
+articleElement.appendChild(divElement4);
+
+document.querySelectorAll('section')[0].appendChild(articleElement);

test/manual/webpack.config.js

@@ -14,6 +14,21 @@ module.exports = {
     rules: [
       {
         test: /\.css$/i,
+        exclude: [/\.module\.css$/i, /\.lazy\.css$/i, /\.link\.css$/i],
+        use: [
+          {
+            loader: require.resolve('../../dist/index.js'),
+          },
+          {
+            loader: 'css-loader',
+            options: {
+              sourceMap: ENABLE_SOURCE_MAP,
+            },
+          },
+        ],
+      },
+      {
+        test: /\.module\.css$/i,
         exclude: [/\.lazy\.css$/i, /\.link\.css$/i],
         use: [
           {
@@ -23,6 +38,7 @@ module.exports = {
             loader: 'css-loader',
             options: {
               sourceMap: ENABLE_SOURCE_MAP,
+              modules: true,
             },
           },
         ],