fix: add support for aliases starting with / (options.alias) (webpack#597)

* Add support for alias starting with /

* startByAlias -> isAlias

Author: atinux

lib/loader.js

@@ -42,6 +42,7 @@ module.exports = function(content, map) {
 		from: loaderUtils.getRemainingRequest(this).split("!").pop(),
 		to: loaderUtils.getCurrentRequest(this).split("!").pop(),
 		query: query,
+		resolve: resolve,
 		minimize: this.minimize,
 		loaderContext: this,
 		sourceMap: sourceMap

lib/processCss.js

@@ -83,6 +83,11 @@ var parserPlugin = postcss.plugin("css-loader-parser", function(options) {
 			exports[exportName] = replaceImportsInString(exports[exportName]);
 		});
 
+		function isAlias(url) {
+			// Handle alias starting by / and root disabled
+			return url !== options.resolve(url)
+		}
+
 		function processNode(item) {
 			switch (item.type) {
 				case "value":
@@ -98,7 +103,7 @@ var parserPlugin = postcss.plugin("css-loader-parser", function(options) {
 					}
 					break;
 				case "url":
-					if (options.url && item.url.replace(/\s/g, '').length && !/^#/.test(item.url) && loaderUtils.isUrlRequest(item.url, options.root)) {
+					if (options.url && item.url.replace(/\s/g, '').length && !/^#/.test(item.url) && (isAlias(item.url) || loaderUtils.isUrlRequest(item.url, options.root))) {
 						// Don't remove quotes around url when contain space
 						if (item.url.indexOf(" ") === -1) {
 							item.stringType = "";
@@ -149,7 +154,8 @@ module.exports = function processCss(inputSource, inputMap, options, callback) {
 		root: root,
 		mode: options.mode,
 		url: query.url !== false,
-		import: query.import !== false
+		import: query.import !== false,
+		resolve: options.resolve
 	};
 
 	var pipeline = postcss([

test/aliasTest.js

@@ -28,3 +28,30 @@ describe("alias", function() {
 	test("exactMatch", css, exports.exactMatch, aliasOptions({ "./path/to/file.png$": "module/file.png" }));
 	test("notExactMatch", css, exports.notExactMatch, aliasOptions({ "./path/to/file.jpg$": "module/file.jpg" }));
 });
+
+describe("alias starting with /", function() {
+	var css = ".className { background: url(/path/to/file.png); }";
+	var exports = {
+		without: [
+			[1, ".className { background: url(/path/to/file.png); }", ""]
+		],
+		onlyModule: [
+			[1, ".className { background: url({module/file.png}); }", ""]
+		],
+		exactMatch: [
+			[1, ".className { background: url({module/file.png}); }", ""]
+		],
+		notExactMatch: [
+			[1, ".className { background: url(/path/to/file.png); }", ""]
+		]
+	};
+
+	function aliasOptions(alias) {
+		return { query: { alias: alias }}
+	}
+
+	test("without", css, exports.without);
+	test("onlyModule", css, exports.onlyModule, aliasOptions({ "/path/to": "module" }));
+	test("exactMatch", css, exports.exactMatch, aliasOptions({ "/path/to/file.png$": "module/file.png" }));
+	test("notExactMatch", css, exports.notExactMatch, aliasOptions({ "/path/to/file.jpg$": "module/file.jpg" }));
+});