anchor.diff:        assembler.addUnlinkedUnitViaUri(uri, unit);
       });
       return assembler.assemble();
  -  }
  -}
  -
  -/// [_FilesToLink] stores information about a set of files to be linked
  -/// together.  This information is grouped into a class to allow it to be reset
  -/// easily when [_SummaryBaseTestStrategyTwoPhase._createLinkerInputs] is
  -/// called.
  -///
  -/// The generic parameter [U] is the type of information stored for each
  -/// compilation unit.
  -class _FilesToLink<U> {
  -  /// Map from absolute URI to the [U] for each compilation unit passed to
  -  /// [addNamedSource].
  -  Map<String, U> uriToUnit = <String, U>{};
  -
  -  /// Information about summaries to be included in the link process.
  -  SummaryDataStore summaryDataStore = new SummaryDataStore([]);
  -}
  -
  -/// Instances of the class [_LinkerInputs] encapsulate the necessary information
  -/// to pass to the summary linker.
  -class _LinkerInputs {
  -  final bool _allowMissingFiles;
  -  final Map<String, UnlinkedUnit> _uriToUnit;
  -  final Uri _testDartUri;
  -  final UnlinkedUnit _unlinkedDefiningUnit;
  -  final Map<String, LinkedLibrary> _dependentLinkedLibraries;
  -  final Map<String, UnlinkedUnit> _dependentUnlinkedUnits;
  -
  -  _LinkerInputs(
  -      this._allowMissingFiles,
  -      this._uriToUnit,
  -      this._testDartUri,
  -      this._unlinkedDefiningUnit,
  -      this._dependentLinkedLibraries,
  -      this._dependentUnlinkedUnits);
  -
  -  Set<String> get linkedLibraries => _uriToUnit.keys.toSet();
  -
  -  String getDeclaredVariable(String name) {
  -    return null;
  -  }
  -
  -  LinkedLibrary getDependency(String absoluteUri) {
  -    Map<String, LinkedLibrary> sdkLibraries =
  -        SerializedMockSdk.instance.uriToLinkedLibrary;
  -    LinkedLibrary linkedLibrary =
  -        sdkLibraries[absoluteUri] ?? _dependentLinkedLibraries[absoluteUri];
  -    if (linkedLibrary == null && !_allowMissingFiles) {
  -      Set<String> librariesAvailable = sdkLibraries.keys.toSet();
  -      librariesAvailable.addAll(_dependentLinkedLibraries.keys);
  -      fail('Linker unexpectedly requested LinkedLibrary for "$absoluteUri".'
  -          '  Libraries available: ${librariesAvailable.toList()}');
  -    }
  -    return linkedLibrary;
  -  }
  -
  -  UnlinkedUnit getUnit(String absoluteUri) {
  -    if (absoluteUri == null) {
  -      return null;
  -    }
  -    UnlinkedUnit unit = _uriToUnit[absoluteUri] ??
  -        SerializedMockSdk.instance.uriToUnlinkedUnit[absoluteUri] ??
  -        _dependentUnlinkedUnits[absoluteUri];
  -    if (unit == null && !_allowMissingFiles) {
  -      fail('Linker unexpectedly requested unit for "$absoluteUri".');
  -    }
  -    return unit;
  -  }
  -}
  -
  -/// Implementation of [SummaryBaseTestStrategy] that drives summary generation
  -/// using the old two-phase API.
  -abstract class _SummaryBaseTestStrategyTwoPhase
  -    implements SummaryBaseTestStrategy {
  -  /// Information about the files to be linked.
  -  _FilesToLink<UnlinkedUnitBuilder> _filesToLink =
  -      new _FilesToLink<UnlinkedUnitBuilder>();
  -
  -  _LinkerInputs _linkerInputs;
  -
  -  bool get _allowMissingFiles;
  -
  -  @override
  -  void addNamedSource(String filePath, String contents) {
  -    CompilationUnit unit = _parseText(contents);
  -    UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(unit);
  -    _filesToLink.uriToUnit[absUri(filePath)] = unlinkedUnit;
     }
   
     UnlinkedUnitBuilder createUnlinkedSummary(Uri uri, String text) =>
  
positive.code: 
    LibraryElementInBuildUnit get testLibrary;
  
    /// Add the given package bundle as a dependency so that it may be referenced
    /// by the files under test.
    void addBundle(String path, PackageBundle bundle);
  
    void createLinker(String text, {String path: '/test.dart'});
  
    /// Link together the given file, along with any other files passed to
    /// [addNamedSource], to form a package bundle.  Reset the state of the
    /// buffers accumulated by [addNamedSource] and [addBundle] so that further
    /// bundles can be created.
    PackageBundleBuilder createPackageBundle(String text,
        {String path: '/test.dart', String uri});
  }
  
  /// Implementation of [SummaryLinkerTestStrategy] that drives summary generation
  
negative.code: 
    @override
    bool get _allowMissingFiles => false;
  
    @override
    void createLinker(String text, {String path: '/test.dart'}) {
  