anchor.diff:  class AssistProcessorTest_Driver extends AssistProcessorTest {
     @override
     bool get enableNewAnalysisDriver => true;
  -
  -  @failingTest
  -  @override
  -  test_addTypeAnnotation_local_OK_addImport_notLibraryUnit() {
  -    return super.test_addTypeAnnotation_local_OK_addImport_notLibraryUnit();
  -  }
  -
  -  @failingTest
  -  @override
  -  test_invalidSelection() {
  -    return super.test_invalidSelection();
  -  }
   }
   
   class _DartAssistContextForValues implements DartAssistContext {
  
positive.code:     Source appSource = addSource('/app.dart', appCode);
      testSource = addSource('/test.dart', testCode);
      // resolve
      context.resolveCompilationUnit2(appSource, appSource);
      testUnit = context.resolveCompilationUnit2(testSource, appSource);
      testUnitElement = testUnit.element;
      testLibraryElement = testUnitElement.library;
      // prepare the assist
      offset = findOffset('v = ');
      assist = await _assertHasAssist(DartAssistKind.ADD_TYPE_ANNOTATION);
  
negative.code: 
    test_invalidSelection() async {
      await resolveTestUnit('');
      offset = -1;
      length = 0;
      List<Assist> assists = await _computeAssists();
      expect(assists, isEmpty);
    }
  
  