test: empty chunk

package.json

@@ -74,7 +74,7 @@
     "npm-run-all": "^4.1.5",
     "prettier": "^2.1.1",
     "standard-version": "^9.0.0",
-    "webpack": "^4.44.1",
+    "webpack": "^4.44.2",
     "webpack-cli": "^3.3.6",
     "webpack-dev-server": "^3.7.2"
   },

test/cases/split-chunks-all/a.js

@@ -0,0 +1 @@
+import './style.css';

test/cases/split-chunks-all/b.js

@@ -0,0 +1 @@
+import './style.css';

test/cases/split-chunks-all/expected/webpack-4/styles~a~b.css

@@ -0,0 +1,4 @@
+body {
+  background: red;
+}
+

test/cases/split-chunks-all/expected/webpack-5/2.css

@@ -0,0 +1,4 @@
+body {
+  background: red;
+}
+

test/cases/split-chunks-all/index.js

@@ -0,0 +1 @@
+import './style.css';

test/cases/split-chunks-all/style.css

@@ -0,0 +1,3 @@
+body {
+  background: red;
+}

test/cases/split-chunks-all/webpack.config.js

@@ -0,0 +1,36 @@
+import webpack from 'webpack';
+
+import Self from '../../../src';
+
+module.exports = {
+  entry: {
+    a: './a.js',
+    b: './b.js',
+  },
+  module: {
+    rules: [
+      {
+        test: /\.css$/,
+        use: [Self.loader, 'css-loader'],
+      },
+    ],
+  },
+  optimization: {
+    splitChunks: {
+      cacheGroups: {
+        styles:
+          webpack.version[0] === '4'
+            ? {
+                chunks: 'all',
+                enforce: true,
+              }
+            : {
+                type: 'css/mini-extract',
+                chunks: 'all',
+                enforce: true,
+              },
+      },
+    },
+  },
+  plugins: [new Self()],
+};