actually skip loader if didn't pass test

README.md

@@ -160,6 +160,8 @@ Use a loader, currently built-in loaders are:
 - `stylus` (TODO)
 - `less` (TODO)
 
+They are executed from right to left.
+
 ### loaders
 
 Type: `Loader[]`

src/loaders.js

@@ -44,7 +44,15 @@ export default class Loaders {
         id,
         sourceMap
       }
-      return v => loader.process.call(loaderContext, v)
+      return v => {
+        // Only process if it's postcss loader
+        // Or passed `test`
+        if (name === 'postcss' || loader.test.test(id)) {
+          return loader.process.call(loaderContext, v)
+        }
+        // Otherwise directly return input value
+        return v
+      }
     }), { code, map })
   }
 

test/__snapshots__/index.test.js.snap

@@ -433,6 +433,46 @@ console.log(css, css$1);
 "
 `;
 
+exports[`skip-loader: js code 1`] = `
+"'use strict';
+
+function __$styleInject(css, ref) {
+  if ( ref === void 0 ) ref = {};
+  var insertAt = ref.insertAt;
+
+  if (!css) { return }
+
+  var head = document.head || document.getElementsByTagName('head')[0];
+  var style = document.createElement('style');
+  style.type = 'text/css';
+
+  if (insertAt === 'top') {
+    if (head.firstChild) {
+      head.insertBefore(style, head.firstChild);
+    } else {
+      head.appendChild(style);
+    }
+  } else {
+    head.appendChild(style);
+  }
+
+  if (style.styleSheet) {
+    style.styleSheet.cssText = css;
+  } else {
+    style.appendChild(document.createTextNode(css));
+  }
+}
+
+var css = \\"body {\\\\n  color: red;\\\\n}\\\\n\\";
+__$$styleInject(css);
+
+var css$1 = \\".bar {\\\\n  color: red;\\\\n}\\\\n\\";
+__$$styleInject(css$1);
+
+console.log(css, css$1);
+"
+`;
+
 exports[`sourcemap:inline: js code 1`] = `
 "'use strict';
 

test/index.test.js

@@ -215,3 +215,20 @@ snapshot({
     ]
   }
 })
+
+snapshot({
+  title: 'skip-loader',
+  input: 'simple/index.js',
+  options: {
+    use: ['loader'],
+    loaders: [
+      {
+        name: 'loader',
+        test: /\.random$/,
+        process() {
+          return 'lol'
+        }
+      }
+    ]
+  }
+})