used lookupInScope(name) to find the qualified names in comments.

pkg/docgen/test/single_library_test.dart

 library single_library_test;
 
 import 'dart:io'; 
 
 import 'package:unittest/unittest.dart';
 
 import '../lib/docgen.dart';
 import '../../../sdk/lib/_internal/compiler/implementation/filenames.dart';
 
 main() {
   group('Generate docs for', () {
     test('one simple file.', () {
       // TODO(janicejl): Instead of creating a new file, should use an in-memory
       // file for creating the mirrorSystem. Example of the util function in 
       // sdk/lib/_internal/compiler/implementation/mirrors/mirrors_util.dart. 
       // Example of the test is in file mirrors_lookup_test.dart
       var file = new File('test.dart');
       file.writeAsStringSync('''
   library test;
   /**
-   * Doc comment for class A.
+   * Doc comment for class [A].
    * 
    * Multiline Test
    */
   /*
    * Normal comment for class A.
    */
   class A {
     
-    /**
-     * Markdown _test_ for **class** [A] 
-     */
     int _someNumber;
     
     A() {
       _someNumber = 12;
     }
     
-    void doThis(int a) {
-      print(a);
+    /**
+     * Test for linking to parameter [A]
+     */
+    void doThis(int A) {
+      print(A);
     }
   }
   
   main() {
     A a = new A();
     a.doThis(5);
   }
       ''');
       
       getMirrorSystem(['test.dart'],'', parseSdk: false)
@@ skipping 21 matching lines @@
           
           var functionParameters = [];
           functions.forEach((e) {
             functionParameters.addAll(e.parameters.values); 
           });
           expect(functionParameters.every((e) => e is Parameter), isTrue);
     
           var variables = library.variables.values;
           expect(variables.every((e) => e is Variable), isTrue);
           
+          /// Testing fixReference 
+          // Testing Doc comment for class [A].
+          var libraryMirror = mirrorSystem.libraries[testLibraryUri];
+          var classMirror = libraryMirror.classes.values.first;
+          var classDocComment = fixReference('A', libraryMirror, 
+              classMirror, null).children.first.text;
+          expect(classDocComment == 'test.A', isTrue);
+          
+          // Test for linking to parameter [A]
+          var methodMirror = classMirror.methods['doThis'];
+          var methodParameterDocComment = fixReference('A', libraryMirror,
+              classMirror, methodMirror).children.first.text;
+          expect(methodParameterDocComment == 'test.A.doThis#A', isTrue);
+          
+          // Testing trying to refer to doThis function
+          var methodDocComment = fixReference('doThis', libraryMirror, 
+              classMirror, methodMirror).children.first.text;
+          expect(methodDocComment == 'test.A.doThis', isTrue);
+          
+          // Testing something with no reference
+          var libraryDocComment = fixReference('foobar', libraryMirror,
+              classMirror, methodMirror).children.first.text;
+          expect(libraryDocComment == 'foobar', isTrue);
+          
           file.deleteSync();
         }));
     });
   });
 }