support for transformers

src/utils/load.js

@@ -1,6 +1,10 @@
 import { readFileSync } from 'sander';
 
 export function defaultLoader ( path, options ) {
-	// TODO support plugins and transformers?
+	// TODO support plugins e.g. !css and !json?
-	return readFileSync( path, { encoding: 'utf-8' });
+	const source = readFileSync( path, { encoding: 'utf-8' });
+
+	return options.transform.reduce( ( source, transformer ) => {
+		return transformer( source, path );
+	}, source );
 }

test/function/transformer-multiple/_config.js

@@ -0,0 +1,21 @@
+var assert = require( 'assert' );
+
+module.exports = {
+	description: 'accepts multiple transformer functions',
+	options: {
+		transform: [
+			function ( code, path ) {
+				return code.replace( /MAGIC_NUMBER/g, 3 );
+			},
+
+			function ( code, path ) {
+				return code.replace( /\d+/g, function ( match ) {
+					return 2 * +match;
+				});
+			}
+		]
+	},
+	exports: function ( exports ) {
+		assert.equal( exports.magicNumber, 6 );
+	}
+}

test/function/transformer-multiple/foo.js

@@ -0,0 +1 @@
+export default MAGIC_NUMBER;

test/function/transformer-multiple/main.js

@@ -0,0 +1,3 @@
+import foo from './foo';
+
+export var magicNumber = foo;

test/function/transformer-single/_config.js

@@ -0,0 +1,13 @@
+var assert = require( 'assert' );
+
+module.exports = {
+	description: 'accepts a single transformer function',
+	options: {
+		transform: function ( code, path ) {
+			return code.replace( /MAGIC_NUMBER/g, 3 );
+		}
+	},
+	exports: function ( exports ) {
+		assert.equal( exports.magicNumber, 3 );
+	}
+}

test/function/transformer-single/foo.js

@@ -0,0 +1 @@
+export default MAGIC_NUMBER;

test/function/transformer-single/main.js

@@ -0,0 +1,3 @@
+import foo from './foo';
+
+export var magicNumber = foo;