Dapper Query Map Collections

DatabaseReader.cs

 public IEnumerable<T1> ReadWithMap<T1, T2, TReturn>(Func<T1, object> key, Func<T1, string> targetMap) where TReturn : T1
        {
            var lookup = new Dictionary<object, T1>();
            var targetType = typeof(T1);
            var propertyFlags = BindingFlags.Public | BindingFlags.Instance;

            gridReader.Read<T1, T2, T1>((t1, t2) =>
            {
                if (!lookup.TryGetValue(key(t1), out T1 t1Return))
                {
                    lookup.Add(key(t1), t1Return = t1);
                }
                MapTargetProperty(targetMap(t1Return), t2, t1Return);
                return t1;
            });

            return lookup.Values;
        }
        
        private void MapTargetProperty(string propertyName, object source, object target)
        {
            if (source == null)
            {
                return;
            }
            var propertyFlags = BindingFlags.Public | BindingFlags.Instance;

            var targetProperty = target.GetType().GetProperty(propertyName, propertyFlags);
            var addMethod = targetProperty.PropertyType.GetMethod("Add");
            addMethod.Invoke(targetProperty.GetValue(target, null), new object[] { source });
        }

SampleTest.cs

        [Fact]
        public async Task Test1()
        {
            var sqlQueries = @"
                select A.Id, A.TypeId, A.PublishedAt, C.Id, C.Name, C.Surname, C.SecondSurname from Cards A
                left join CardMentions B on A.Id = B.CardId
				left join Users C on C.Id = B.UserId ";

            var sqlConn = new SqlConnection("Server=.;Database=UriaDepartmentalSites;Trusted_Connection=True; MultipleActiveResultSets=True");
           
	    var database = new Database(sqlConn);
            var reader = await database.QueryMultipleAsync(sqlQueries);
            var result = reader.ReadWithMap<Card, User, Card>(c => c.Id, c => nameof(c.Users));

            result.ElementAt(0).Users.Count().Should().Be(2);
            result.ElementAt(5).Users.Count().Should().Be(3);

        }