Improve source map support

- Populate the from, to, map, and compress options from webpack info
- Pass on generated source map

Author: Andy VanWagoner

index.js

@@ -1,16 +1,37 @@
 var cssnext = require("cssnext")
 var assign = require("object-assign")
+var loaderUtils = require("loader-utils")
 
-function cssnextLoader(contents){
+function defaultOptions(context, map){
+  var options = {}
+  options.from = loaderUtils.getRemainingRequest(context)
+  options.to = loaderUtils.getRemainingRequest(context)
+  if (context.sourceMap) {
+    options.map = {
+      inline: false,
+      annotation: false,
+      prev: map
+    }
+  }
+  options.compress = context.minimize
+  return options
+}
+
+function cssnextLoader(contents, map){
   this.cacheable()
-  var options = assign({}, this.options.cssnext)
+  var options = assign({}, defaultOptions(this, map), this.options.cssnext)
   options.features = assign({}, this.options.cssnext ? this.options.cssnext.features : null)
   options.features.import = assign({}, options.features.import || null)
   options.features.import.onImport = function(files){
     files.forEach(this.addDependency)
   }.bind(this)
   try {
-    return cssnext(contents, options)
+    var result = cssnext(contents, options)
+    if (result.css) {
+      this.callback(null, result.css, result.map)
+    } else {
+      return result
+    }
   } catch(err) {
     this.emitError(err)
   }

package.json

@@ -4,7 +4,7 @@
   "description": "webpack loader for cssnext",
   "main": "index.js",
   "scripts": {
-    "start" : "npm install && npm test",
+    "start": "npm install && npm test",
     "test": "tape test/**.js"
   },
   "repository": {
@@ -25,6 +25,7 @@
   "homepage": "https://github.com/cssnext/cssnext-loader",
   "dependencies": {
     "cssnext": "^0.6.0",
+    "loader-utils": "^0.2.5",
     "object-assign": "^2.0.0"
   },
   "devDependencies": {

test/index.js

@@ -24,8 +24,42 @@ tape("cssnext-loader", function(test){
         file += chunk
       })
       .on("end", function(){
-        test.equal(/color\s*:\s*red/.test(file), true)
+        test.ok(/color\s*:\s*red/.test(file), "css transformed")
+        test.notOk(/# sourceMappingURL=.*\s*$/.test(file), "source map annotation not added")
         test.end()
       })
   })
 })
+
+tape("cssnext-loader source maps", function(test){
+  webpack({
+    entry: "./test/fixtures/index.js",
+    output: {
+      path: "./test/output/",
+      filename: "bundle.js"
+    },
+    debug: true,
+    devtool: 'source-map',
+    cssnext : {
+      features : {
+        import : {
+          path : ["test/fixtures/"]
+        }
+      }
+    }
+  }, function(err, stat){
+    var file = ""
+    test.plan(3)
+    fs.createReadStream("test/output/bundle.js")
+      .on("data", function(chunk){
+        file += chunk
+      })
+      .on("end", function(){
+        test.ok(/color\s*:\s*red/.test(file), "css transformed")
+        test.ok(/# sourceMappingURL=.*\s*$/.test(file), "source map annotation added")
+      })
+    fs.exists("test/output/bundle.js.map", function(exists){
+      test.ok(exists, "source map exists")
+    })
+  })
+})