validator.py

import sys
import psycopg2
import configparser


def connect_to_warehouse():
    # get db connection parameters from the conf file
    parser = configparser.ConfigParser(interpolation=None)
    parser.read('pipeline.conf')
    dbname = parser.get('aws_creds', 'database')
    user = parser.get('aws_creds', 'user')
    password = parser.get('aws_creds', 'password')
    host = parser.get('aws_creds', 'host')
    port = parser.get('aws_creds', 'port')

    rs_con = psycopg2.connect(
        dbname=dbname,
        user=user,
        password=password,
        host=host,
        port=port
    )

    return rs_con

# execute a test made up of two scripts
# and a comparison operator
# Returns the true/false for test pass/fail


def execute_test(
        db_con,
        script_1,
        script_2,
        comp_operator):
    # execute the 1st script and store the result
    cursor = db_con.cursor()
    sql_file = open(script_1, 'r')
    cursor.execute(sql_file.read())
    record = cursor.fetchone()
    result_1 = record[0]
    db_con.commit()
    cursor.close()

    # execute the 2nd script and store the result
    cursor = db_con.cursor()
    sql_file = open(script_2, 'r')
    cursor.execute(sql_file.read())

    record = cursor.fetchone()
    result_2 = record[0]
    db_con.commit()
    cursor.close()

    print("result 1 = " + str(result_1))
    print("result 2 = " + str(result_2))

    # compare values based on the comp operator
    if comp_operator == 'equals':
        return result_1 == result_2
    elif comp_operator == 'greater_equals':
        return result_1 >= result_2
    elif comp_operator == 'greater':
        return result_1 > result_2
    elif comp_operator == 'less_equals':
        return result_1 <= result_2
    elif comp_operator == 'less':
        return result_1 < result_2
    elif comp_operator == 'not_equal':
        return result_1 != result_2

    # if we made it here, something went wrong
    return False


if __name__ == '__main__':
    if len(sys.argv) == 2 and sys.argv[1] == '-h':
        if len(sys.argv) == 2 and sys.argv[1] == "-h":
            print("Usage: python validator.py"
                  + "script1.sql script2.sql "
                  + "comparison_operator")
            print("Valid comparison_operator values:")
            print("equals")
            print("greater_equals")
            print("greater")
            print("less_equals")
            print("less")
            print("not_equal")

            exit(0)
        if len(sys.argv) != 4:
            print("Usage: python validator.py"
                  + "script1.sql script2.sql "
                  + "comparison_operator")
            exit(-1)

    script_1 = sys.argv[1]
    script_2 = sys.argv[2]
    comp_operator = sys.argv[3]

    # connect to the data warehouse
    db_con = connect_to_warehouse()

    # execute the validation test
    test_result = execute_test(
        db_con, script_1, script_2, comp_operator
    )
    print('Result of test: ' + str(test_result))

    if test_result == True:
        exit(0)
    else:
        exit(-1)