fixes #201, add support for custom URL mapping

lib/src/testing.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.testing;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
@@ skipping 29 matching lines @@
 ///
 ///     testChecker({
 ///       '/main.dart': '''
 ///           testMethod() {
 ///             dynamic x = /*warning:Box*/3;
 ///           }
 ///       '''
 ///     });
 ///
 CheckerResults testChecker(Map<String, String> testFiles,
-    {bool allowConstCasts: true, String sdkDir,
+    {bool allowConstCasts: true, String sdkDir, customUrlMappings: const {},
     CheckerReporter createReporter(AnalysisContext context),
     covariantGenerics: true, relaxedCasts: true,
     inferDownwards: RulesOptions.inferDownwardsDefault,
     inferFromOverrides: ResolverOptions.inferFromOverridesDefault,
     inferTransitively: ResolverOptions.inferTransitivelyDefault,
     nonnullableTypes: TypeOptions.NONNULLABLE_TYPES,
     wrapClosures: RulesOptions.wrapClosuresDefault}) {
   expect(testFiles.containsKey('/main.dart'), isTrue,
       reason: '`/main.dart` is missing in testFiles');
 
   var provider = createTestResourceProvider(testFiles);
   var uriResolver = new TestUriResolver(provider);
 
   var options = new CompilerOptions(
       allowConstCasts: allowConstCasts,
       covariantGenerics: covariantGenerics,
       relaxedCasts: relaxedCasts,
       inferDownwards: inferDownwards,
       inferFromOverrides: inferFromOverrides,
       inferTransitively: inferTransitively,
       nonnullableTypes: nonnullableTypes,
       wrapClosures: wrapClosures,
       useMockSdk: sdkDir == null,
       dartSdkPath: sdkDir,
       runtimeDir: '/dev_compiler_runtime/',
-      entryPointFile: '/main.dart');
+      entryPointFile: '/main.dart',
+      customUrlMappings: customUrlMappings);
 
   var context = createAnalysisContext(options, fileResolvers: [uriResolver]);
 
   // Run the checker on /main.dart.
   var mainFile = new Uri.file('/main.dart');
   TestReporter testReporter;
   CheckerReporter reporter;
   if (createReporter == null) {
     reporter = testReporter = new TestReporter(context);
   } else {
@@ skipping 213 matching lines @@
     expect(tokens[1], "should", reason: 'invalid error descriptor');
     expect(tokens[2], "be", reason: 'invalid error descriptor');
     if (tokens[0] == "pass") return null;
     // TODO(leafp) For now, we just use whatever the current expectation is,
     // eventually we could do more automated reporting here.
     return _parse(tokens[0]);
   }
 
   String toString() => '$level $type';
 }