anchor.diff:      });
   
       test('Looks up agent if not provided in the context', () async {
  -      RequestContext context = RequestContext();
  +      FakeRequestContext context = FakeRequestContext();
         Map<String, dynamic> request = <String, dynamic>{'AgentID': 'aid'};
         when(db.lookup<Agent>(any)).thenAnswer((Invocation invocation) {
           return Future<List<Agent>>.value(<Agent>[agent]);
  
positive.code: class MockDatastoreDB extends Mock implements DatastoreDB {}
  
  class MockQuery<T extends Model> extends Mock implements Query<T> {}
  
negative.code:     });
  
      test('returns empty response if no task available', () async {
        FakeRequestContext context = FakeRequestContext()..agent = agent;
        Map<String, dynamic> request = <String, dynamic>{'AgentID': 'aid'};
        when(taskProvider.findNextTask(agent)).thenAnswer((Invocation invocation) {
          return Future<TaskAndCommit>.value(null);
  