anchor.diff:  class PackageBuildPackageUriResolverTest extends _BaseTest {
     PackageBuildWorkspace workspace;
     PackageBuildPackageUriResolver resolver;
  -  UriResolver packageUriResolver;
  +  MockUriResolver packageUriResolver;
   
     Uri addPackageSource(String path, String uriStr, {bool create: true}) {
       Uri uri = Uri.parse(uriStr);
  
positive.code:   });
  }
  
  class MockContextBuilder extends Mock implements ContextBuilder {}
  
  class MockPackages extends Mock implements Packages {}
  
  class MockUriResolver extends Mock implements UriResolver {}
  
  @reflectiveTest
  class PackageBuildFileUriResolverTest extends _BaseTest {
  
negative.code: import 'package:analyzer/src/context/builder.dart';
  import 'package:analyzer/src/generated/package_build.dart';
  import 'package:analyzer/src/generated/source.dart';
  import 'package:package_config/packages.dart';
  import 'package:test/test.dart';
  import 'package:test_reflective_loader/test_reflective_loader.dart';
  