fix(doc-gen): correctly transform index files

Closes #3021

docs/spec/writerSpec.js

@@ -1,7 +1,26 @@
-var writer = require('../src/writer.js');
+var writer,
+    rewire = require('rewire');
+
+function mockResolvedPromise(resolvedValue) {
+  return {
+    then: function(success, failure) {
+      success(resolvedValue);
+    }
+  };
+}
+
 describe('writer', function() {
+
+  beforeEach(function() {
+     writer = rewire('../src/writer.js');
+  });
+
   describe('toString', function() {
-    var toString = writer.toString;
+    var toString;
+
+    beforeEach(function() {
+      toString = writer.toString;
+    });
 
     it('should merge string', function() {
       expect(toString('abc')).toEqual('abc');
@@ -31,4 +50,15 @@ describe('writer', function() {
       expect(content).toBe('ng super jqlite manifest');
     });
   });
+
+  describe('copy', function() {
+    it('should call the transformation function', function() {
+      var readMock = jasmine.createSpy('readMock').andReturn(mockResolvedPromise('DUMMY CONTENT'));
+      writer.__set__("qfs.read", readMock);
+      var transformationFn = jasmine.createSpy('transformationFn');
+      writer.copy('from', 'to', transformationFn, 'arg1', 'arg2');
+      expect(readMock).toHaveBeenCalled();
+      expect(transformationFn).toHaveBeenCalledWith('DUMMY CONTENT', 'arg1', 'arg2');
+    });
+  });
 });

docs/src/writer.js

@@ -51,13 +51,19 @@ exports.copyTemplate = function(filename) {
  * @param  transform{function=} transfromation function to be applied before return
  */
 exports.copy = function(from, to, transform) {
+  var transformArgs = Array.prototype.slice.call(arguments, 3);
+
   from = pathUtils.normalize(from);
   to = pathUtils.normalize(to);
 
   // We have to use binary reading, Since some characters are unicode.
   return qfs.read(from, 'b').then(function(content) {
     if (transform) {
-      content = transform.call(null, content.toString(), from, to, transform);
+      // Pass any extra arguments, e.g.
+      // `copy(from, to, transform, extra1, extra2, ...)`
+      // to the transform function
+      transformArgs.unshift(content.toString());
+      content = transform.apply(null, transformArgs);
     }
     return output(to, content);
   });