public MockDbSet()
 {
     _data            = new ObservableCollection <TEntity>();
     _query           = _data.AsQueryable();
     _queryProvier    = new MockDbSetAsyncQueryProvider <TEntity>(_query.Provider);
     _asyncEnumerator = new MockDbSetAsyncEnumerator <TEntity>(_data.GetEnumerator());
 }
        internal MockDbSetAsyncEnumerable(Expression expression)
            : base(expression)
        {
            if (expression == null)
            {
                throw new System.ArgumentNullException(nameof(expression));
            }

            _asyncQueryProvider = new MockDbSetAsyncQueryProvider <TEntity>(this);
            _asynEnumerator     = new MockDbSetAsyncEnumerator <TEntity>(this.AsEnumerable().GetEnumerator());
        }