Dapper.Contrib Suggest to add InsertOrUpdate Functions

The proposal references ITransaction.CommitTransaction and the external SqlBulkTools library, but names no repository files or tests. Start by locating the transaction implementation and comparing the referenced Insert, Update, and Delete behavior. Define the public API and expected matching, deletion, identity, and transaction semantics; done requires tests for those cases.

It is recommended to refer to this library to join InsertOrUpdate Functions https://github.com/olegil/SqlBulkTools
I can pass in an entity for automatic comparison Insert Update Delete Operation

void ITransaction.CommitTransaction(string connectionName, SqlCredential credentials, SqlConnection connection)
        {
            if (!_list.Any())
            {
                return;
            }

            if (_disableAllIndexes && (_disableIndexList != null && _disableIndexList.Any()))
            {
                throw new InvalidOperationException("Invalid setup. If \'TmpDisableAllNonClusteredIndexes\' is invoked, you can not use the \'AddTmpDisableNonClusteredIndex\' method.");
            }

            if (_matchTargetOn.Count == 0)
            {
                throw new InvalidOperationException("MatchTargetOn list is empty when it's required for this operation. " +
                                                    "This is usually the primary key of your table but can also be more than one column depending on your business rules.");
            }
            
            DataTable dt = _helper.ToDataTable(_list, _columns, _customColumnMappings, _matchTargetOn, _outputIdentity, _outputIdentityDic);            

            // Must be after ToDataTable is called. 
            _helper.DoColumnMappings(_customColumnMappings, _columns, _matchTargetOn);

            using (SqlConnection conn = _helper.GetSqlConnection(connectionName, credentials, connection))
            {
                conn.Open();
                var dtCols = _helper.GetDatabaseSchema(conn, _schema, _tableName);
               
                using (SqlTransaction transaction = conn.BeginTransaction())
                {
                    try
                    {
                        SqlCommand command = conn.CreateCommand();
                        command.Connection = conn;
                        command.Transaction = transaction;
                        command.CommandTimeout = _sqlTimeout;
                        
                        //Creating temp table on database
                        command.CommandText = _helper.BuildCreateTempTable(_columns, dtCols, _outputIdentity);
                        command.ExecuteNonQuery();

                        _helper.InsertToTmpTable(conn, transaction, dt, _bulkCopyEnableStreaming, _bulkCopyBatchSize,
                            _bulkCopyNotifyAfter, _bulkCopyTimeout, _sqlBulkCopyOptions);

                        if (_disableIndexList != null && _disableIndexList.Any())
                        {
                            command.CommandText = _helper.GetIndexManagementCmd(IndexOperation.Disable, _tableName, _disableIndexList, _disableAllIndexes);
                            command.ExecuteNonQuery();
                        }

                        //if (_outputIdentity)
                        //{
                        //    command.CommandText = _helper.GetOutputCreateTableCmd(_outputIdentity, "#TmpOutput",
                        //        OperationType.Insert);
                        //    command.ExecuteNonQuery();
                        //}

                        string comm =
                            _helper.GetOutputCreateTableCmd(_outputIdentity, "#TmpOutput", OperationType.Insert) +
                            "MERGE INTO " + _helper.GetFullQualifyingTableName(conn.Database, _schema, _tableName) +
                            " WITH (HOLDLOCK) AS Target " +
                            "USING #TmpTable AS Source " +
                            _helper.BuildJoinConditionsForUpdateOrInsert(_matchTargetOn.ToArray(),
                                _sourceAlias, _targetAlias) +
                            "WHEN MATCHED THEN " +
                            _helper.BuildUpdateSet(_columns, _sourceAlias, _targetAlias, _identityColumn) +
                            "WHEN NOT MATCHED BY TARGET THEN " +
                            _helper.BuildInsertSet(_columns, _sourceAlias, _identityColumn) +
                            (_deleteWhenNotMatchedFlag ? " WHEN NOT MATCHED BY SOURCE THEN DELETE " : " ") +
                            _helper.GetOutputIdentityCmd(_identityColumn, _outputIdentity, "#TmpOutput",
                                OperationType.Insert) +
                            "DROP TABLE #TmpTable;";
                        command.CommandText = comm;
                        command.ExecuteNonQuery();

                        if (_disableIndexList != null && _disableIndexList.Any())
                        {
                            command.CommandText = _helper.GetIndexManagementCmd(IndexOperation.Rebuild, _tableName, _disableIndexList);
                            command.ExecuteNonQuery();
                        }

                        if (_outputIdentity)
                        {
                            command.CommandText = "SELECT InternalId, Id FROM #TmpOutput;";

                            using (SqlDataReader reader = command.ExecuteReader())
                            {
                                var list = _list.ToList();

                                while (reader.Read())
                                {

                                    var test = reader[0];
                                    var test2 = reader[1];

                                    T item;

                                    if (_outputIdentityDic.TryGetValue((int)reader[0], out item))
                                    {
                                        Type type = item.GetType();

                                        PropertyInfo prop = type.GetProperty(_identityColumn);

                                        prop.SetValue(item, reader[1], null);
                                    }


                                }
                            }

                        }

                        transaction.Commit();

                    }

                    catch (SqlException e)
                    {
                        for (int i = 0; i < e.Errors.Count; i++)
                        {
                            // Error 8102 is identity error. 
                            if (e.Errors[i].Number == 8102)
                            {
                                // Expensive call but neccessary to inform user of an important configuration setup. 
                                throw new IdentityException(e.Errors[i].Message);
                            }
                        }

                        transaction.Rollback();
                        throw;
                    }

                    catch (Exception)
                    {
                        transaction.Rollback();
                        throw;
                    }
                    finally
                    {
                        conn.Close();
                    }
                }
            }
        }