How to mock sqlalchemy.engine.cursor.LegacyCursorResult? - pytest

Question

I have the following class that makes connection to MSSQL Server instance in my project,
"""MSSql Connection class."""
import logging
import logging.config
import sqlalchemy
class MSSQLConnection:
_connection = None
_engine = None
def __init__(self, host, database, username, password):
connection_string = self.build_connection_string(
host, database, username, password)
self._engine = sqlalchemy.create_engine(
connection_string, fast_executemany=True,
isolation_level="READ COMMITTED")
def connect(self):
self._connection = self._engine.connect()
def get_result_tuple(self, table):
logger = logging.getLogger()
metadata = sqlalchemy.MetaData()
db_table = sqlalchemy.Table(
table, metadata, autoload=True, autoload_with=self._engine)
query = sqlalchemy.select([db_table])
transaction_id = self.get_transaction_id()
result_proxy = self._connection.execute(query)
return transaction_id, result_proxy
def get_transaction_id(self):
"""Get the transaction id."""
connection = self._connection
sql_query = sqlalchemy.text("SELECT CURRENT_TRANSACTION_ID()")
result = connection.execute(sql_query)
row = result.fetchone()
return row[0]
def build_connection_string(self, host, database, username, password):
connection_string = ('mssql+pyodbc://' + username + ':'
+ password + '#' + host + '/' + database
+ '?driver=ODBC+Driver+17+for+SQL+Server')
return connection_string
I would like to mock the method
get_result_tuple
that returns ´transaction_id´ and instance of sqlalchemy.engine.cursor.LegacyCursorResult.
How to mock sqlalchemy.engine.cursor.LegacyCursorResult and return some dummy data on the ResultProxy object?
The caller has the following code,
mssql_connection = MSSQLConnection(
host, database, username, password)
mssql_connection.connect()
result_tuple = mssql_connection.get_result_tuple(table)
transaction_id, result_proxy = result_tuple
logger.info(f'Transaction id = {transaction_id}')
current_date = date.today().strftime("%Y_%m_%d")
while True:
partial_results = result_proxy.fetchmany(rows_fetch_limit)
results_count = len(partial_results)
if (partial_results == [] or results_count == 0):
return
else:
// other logic
Please advise.