anchor.diff:    });
   }
   
  -class MockContextBuilder extends Mock implements ContextBuilder {}
  -
  -class MockPackages extends Mock implements Packages {}
  -
  -class MockUriResolver extends Mock implements UriResolver {}
  +class MockContextBuilder implements ContextBuilder {
  +  Map<String, Packages> packagesMapMap = <String, Packages>{};
  +  Map<Packages, Map<String, List<Folder>>> packagesToMapMap =
  +      <Packages, Map<String, List<Folder>>>{};
  +
  +  Map<String, List<Folder>> convertPackagesToMap(Packages packages) =>
  +      packagesToMapMap[packages];
  +
  +  Packages createPackageMap(String rootDirectoryPath) =>
  +      packagesMapMap[rootDirectoryPath];
  +
  +  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
  +}
  +
  +class MockPackages implements Packages {
  +  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
  +}
  +
  +class MockUriResolver implements UriResolver {
  +  Map<Uri, Source> resolveAbsoluteMap = {};
  +
  +  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
  +
  +  Source resolveAbsolute(Uri uri, [Uri actualUri]) => resolveAbsoluteMap[uri];
  +}
   
   @reflectiveTest
   class PackageBuildFileUriResolverTest extends _BaseTest {
  
positive.code: class PackageBuildPackageUriResolverTest extends _BaseTest {
    PackageBuildWorkspace workspace;
    PackageBuildPackageUriResolver resolver;
    UriResolver packageUriResolver;
  
    Uri addPackageSource(String path, String uriStr, {bool create: true}) {
      Uri uri = Uri.parse(uriStr);
  
negative.code:     }
      final contextBuilder = new MockContextBuilder();
      final packages = new MockPackages();
      contextBuilder.packagesMapMap[_p(workspacePath)] = packages;
      contextBuilder.packagesToMapMap[packages] = {'project': []};
      workspace =
          PackageBuildWorkspace.find(provider, _p(workspacePath), contextBuilder);
      packageUriResolver = new MockUriResolver();
  