Add sourcemaps test

package.json

@@ -57,7 +57,8 @@
     "rollup-plugin-replace": "^1.0.1",
     "sander": "^0.4.0",
     "source-map": "^0.5.3",
-    "sourcemap-codec": "^1.2.1"
+    "sourcemap-codec": "^1.2.1",
+    "uglify-js": "^2.6.1"
   },
   "dependencies": {
     "chalk": "^1.1.1",

src/utils/transformBundle.js

@@ -1,3 +1,5 @@
+import MagicString from 'magic-string';
+
 export default function transformBundle ( source, transformers ) {
 	if ( typeof source === 'string' ) {
 		source = {
@@ -22,7 +24,16 @@ export default function transformBundle ( source, transformers ) {
 			result.map = JSON.parse( result.map );
 		}
 
-		return result;
+		if (result.map != null) {
+			let map = new MagicString.Bundle().generateMap({});
+			map.file = result.map.file;
+			map.sources = result.map.sources;
+			map.sourcesContent = result.map.sourcesContent;
+			map.names = result.map.names;
+			map.mappings = result.map.mappings;
+			result.map = map;
+		}
 
+		return result;
 	}, source );
 }

test/form/transform-bundle-plugin/_config.js

@@ -4,16 +4,12 @@ module.exports = {
 		plugins: [
 			{
 				transformBundle: function (result) {
-					return {
+					return '/* first plugin */';
-						code: '/* first plugin */'
-					};
 				}
 			},
 			{
 				transformBundle: function (result) {
-					return {
+					return result.code + '\n/* second plugin */';
-						code: result.code + '\n/* second plugin */'
-					};
 				}
 			}
 		]

test/sourcemaps/transform-bundle/_config.js

@@ -0,0 +1,47 @@
+var uglify = require( 'uglify-js' );
+var MagicString = require( 'magic-string' );
+var assert = require( 'assert' );
+var getLocation = require( '../../utils/getLocation' );
+var SourceMapConsumer = require( 'source-map' ).SourceMapConsumer;
+
+module.exports = {
+	description: 'preserves sourcemap chains when transforming',
+	options: {
+		plugins: [
+			{
+				transformBundle: function ( source ) {
+					var options = { fromString: true };
+
+					if ( source.map != null ) {
+						options.inSourceMap = source.map;
+						options.outSourceMap = "out";
+					}
+
+					var result = uglify.minify( source.code, options );
+
+					if (source.map != null) {
+						result.code = result.code.slice( 0, -25 );
+					}
+
+					return result;
+				}
+			}
+		]
+	},
+	test: function ( code, map ) {
+		var smc = new SourceMapConsumer( map );
+
+		var generatedLoc = getLocation( code, code.indexOf( '42' ) );
+		var originalLoc = smc.originalPositionFor( generatedLoc );
+
+		assert.ok( /main/.test( originalLoc.source ) );
+		assert.equal( originalLoc.line, 1 );
+		assert.equal( originalLoc.column, 13 );
+
+		generatedLoc = getLocation( code, code.indexOf( 'log' ) );
+		originalLoc = smc.originalPositionFor( generatedLoc );
+
+		assert.equal( originalLoc.line, 1 );
+		assert.equal( originalLoc.column, 8 );
+	}
+};

test/sourcemaps/transform-bundle/main.js

@@ -0,0 +1 @@
+console.log( 42 );