def setUp(self):
"""`setUp` prepares the data before each test case.
"""
# set up the test constants
self.apr = Decimal('0.350') # 35%
self.limit = Decimal('1000.000') # credit limit in USD
self.period = 30 # payment period in days
# create a database connection to the test db based on the settings
conn = psycopg2.connect(DB_CONN_STRING)
# NOTE: this ideally should not be done and instead each
# transaction has to be handled based on the application
# logic. Since we know that there will not be many
# simultaneous connections to the database in our usecase,
# it is okay to autocommit each SQL query to simply some code.
conn.autocommit = True
# get the cursor object to make queries
self.cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
# set up initial seed data
today = date.today()
self.cursor.execute("""
INSERT INTO
transaction (tstamp, amount, balance, type, description)
VALUES ('%s', 0, %s, 'eot', 'opening balance');
""" % (today, self.limit)) # eot -- END of Term (payment term)
# create the credit manager object
self.cm = CreditManager(self.apr, self.limit, self.period)
class CreditManagerTest(unittest.TestCase):
"""`CreditManagerTest` defines all the unit test
cases for the cmanager module.
"""
def setUp(self):
"""`setUp` prepares the data before each test case.
"""
# set up the test constants
self.apr = Decimal('0.350') # 35%
self.limit = Decimal('1000.000') # credit limit in USD
self.period = 30 # payment period in days
# create a database connection to the test db based on the settings
conn = psycopg2.connect(DB_CONN_STRING)
# NOTE: this ideally should not be done and instead each
# transaction has to be handled based on the application
# logic. Since we know that there will not be many
# simultaneous connections to the database in our usecase,
# it is okay to autocommit each SQL query to simply some code.
conn.autocommit = True
# get the cursor object to make queries
self.cursor = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
# set up initial seed data
today = date.today()
self.cursor.execute("""
INSERT INTO
transaction (tstamp, amount, balance, type, description)
VALUES ('%s', 0, %s, 'eot', 'opening balance');
""" % (today, self.limit)) # eot -- END of Term (payment term)
# create the credit manager object
self.cm = CreditManager(self.apr, self.limit, self.period)
def tearDown(self):
"""`tearDown` restores the state of the system after each test case.
"""
# reset the database by deleting all the data.
self.cursor.execute("TRUNCATE transaction;");
def test_if_payment_on_zero_outstanding_allowed(self):
# make a payment without any withdrawal
self.cm.pay(Decimal('100.00'), 'sample payment')
# check the current due
self.assertEqual(Decimal('-100.00'), self.cm.get_current_due())
def test_payment_of_zero_or_less_amount(self):
self.assertRaises(
InvalidPayment,
self.cm.pay,
amount=Decimal('0.000'),
description='payment number 01'
)
self.assertRaises(
InvalidPayment,
self.cm.pay,
amount=Decimal('-100.000'),
description='payment number 02'
)
def test_payment_with_proper_amount(self):
now1 = datetime.now()
# make a payment
self.assertEqual(self.cm.pay(Decimal('100.000'), 'payment 001'), None)
# verify that the payment is made successfully.
self.cursor.execute("SELECT * FROM transaction OFFSET 1;") # ignore the first one.
results = self.cursor.fetchall()
# check that only one record exists
self.assertEqual(len(results), 1)
# inspect the record
self.assertTrue(results[0]['tstamp'] >= now1)
self.assertEqual(results[0]['amount'], Decimal('100.000'))
self.assertEqual(results[0]['balance'], Decimal('1100.000')) # payment + balance
self.assertEqual(results[0]['description'], 'payment 001')
self.assertEqual(results[0]['type'], 'payment')
now2 = datetime.now()
# make another payment
self.assertEqual(self.cm.pay(Decimal('10.000'), 'payment 002'), None)
# verify that the payment is made successfully.
self.cursor.execute("SELECT * FROM transaction OFFSET 1;") # ignore the first one.
results = self.cursor.fetchall()
# check that two records exist
self.assertEqual(len(results), 2)
# inspect the record
self.assertTrue(results[1]['tstamp'] >= now2 and results[1]['tstamp'] > now1)
self.assertEqual(results[1]['amount'], Decimal('10.000'))
self.assertEqual(results[1]['balance'], Decimal('1110.000')) # payment + balance
self.assertEqual(results[1]['description'], 'payment 002')
self.assertEqual(results[0]['type'], 'payment')
def test_withdrawal_of_zero_less_amount(self):
self.assertRaises(
InvalidWithdrawal,
self.cm.withdraw,
Decimal('0.000'),
'swiped at starbucks'
)
self.assertRaises(
InvalidWithdrawal,
self.cm.withdraw,
Decimal('-10.000'),
'swiped at starbucks'
)
def test_withdrawal_with_proper_amount(self):
now1 = datetime.now()
# make a withdrawal
self.assertEqual(self.cm.withdraw(Decimal('100.000'), 'jewel osco'), None)
# verify that the withdrawal is made successfully.
self.cursor.execute("SELECT * FROM transaction OFFSET 1;") # ignore the first one.
results = self.cursor.fetchall()
# check that only one record exists
self.assertEqual(len(results), 1)
# inspect the record
self.assertTrue(results[0]['tstamp'] >= now1)
self.assertEqual(results[0]['amount'], Decimal('-100.000'))
self.assertEqual(results[0]['balance'], Decimal('900.000')) # payment + balance
self.assertEqual(results[0]['description'], 'jewel osco')
self.assertEqual(results[0]['type'], 'withdrawal')
now2 = datetime.now()
# make another withdrawal
self.cm.withdraw(Decimal('10.000'), 'walmart')
# verify that the withdrawal is made successfully.
self.cursor.execute("SELECT * FROM transaction OFFSET 1;") # ignore the first one.
results = self.cursor.fetchall()
# check that two records exist
self.assertEqual(len(results), 2)
# inspect the record
self.assertTrue(results[1]['tstamp'] >= now2 and results[1]['tstamp'] > now1)
self.assertEqual(results[1]['amount'], Decimal('-10.000'))
self.assertEqual(results[1]['balance'], Decimal('890.000')) # payment + balance
self.assertEqual(results[1]['description'], 'walmart')
self.assertEqual(results[1]['type'], 'withdrawal')
def test_withdrawal_on_zero_balance(self):
# withdraw the entire amount specified in the limit
self.cm.withdraw(self.limit, 'walmart')
# then try again.
self.assertRaises(
WithdrawalDenied,
self.cm.withdraw,
Decimal('10.000'),
'walmart'
)
def test_statement_with_no_transactions(self):
results = self.cm.get_statement()
# inspect the results
self.assertEqual(len(results), 1)
self.assertTrue(results[0].has_key('tstamp'))
self.assertEqual(results[0]['amount'], Decimal('0.000'))
self.assertEqual(results[0]['type'], 'eot')
self.assertEqual(results[0]['description'], 'opening balance')
def test_statement_with_multiple_transactions(self):
now = datetime.now()
# make three different transactions
self.cm.withdraw(Decimal('10.000'), 'walmart')
self.cm.withdraw(Decimal('20.000'), 'jewel osco')
self.cm.pay(Decimal('10.000'), 'payment 001')
results = self.cm.get_statement()
# inspect the results
self.assertEqual(len(results), 4)
# results[0] will be the opening balance line, ignore.
self.assertTrue(results[1]['tstamp'] > now)
self.assertEqual(results[1]['amount'], Decimal('-10.000'))
self.assertTrue(results[2]['tstamp'] > now)
self.assertEqual(results[2]['amount'], Decimal('-20.000'))
self.assertTrue(results[3]['tstamp'] > now)
self.assertEqual(results[3]['amount'], Decimal('10.000'))
# TODO: test statement with transaction dates
def test_due_when_no_transactions_are_done(self):
self.assertEqual(Decimal('0.000'), self.cm.get_current_due())
def test_compute_outstanding_case_02(self):
# case 02: mentioned in the github problem statement
# https://github.com/avantcredit/programming_challenges/blob/master/line_of_credit_test#L32-L35
# on day 1: (ie. after 0 days logically) draws $500 on day 1 (his balance / remaining credit limit is now $500)
day00 = datetime.now()
self.cm.withdraw(Decimal('500.000'), 'first withdraw', day00)
# after 15 days: pays back $200
day15 = day00 + timedelta(days=15)
self.cm.pay(Decimal('200.000'), 'first payment', day15)
# after 25 days: draws another $100
day25 = day00 + timedelta(days=25)
self.cm.withdraw(Decimal('100.000'), 'second withdraw', day25)
# after 29 days: time to check the total payment which he has to make (a.k.a outstanding)
day29 = day00 + timedelta(days=29)
self.assertEqual(self.cm.get_current_due(day29), Decimal('400.000'))
# after 29 days: try calling compute_outstanding. It should fail since
# we haven't reached 30 days.
self.assertRaises(
Exception,
self.cm.compute_outstanding,
day29
)
# after 30 days: 30 days have passed. Let us now compute the outstanding
# and check the total due.
day30 = day00 + timedelta(days=30)
self.assertEqual(self.cm.compute_outstanding(day30), Decimal('411.99'))
def test_compute_outstanding_case_01(self):
# case 01: mentioned in the github problem statement
# https://github.com/avantcredit/programming_challenges/blob/master/line_of_credit_test#L22-L26
# on day 1 (after 0 days technically): draws $500 on day 1 (his balance / remaining credit limit is now $500)
day00 = datetime.now()
self.cm.withdraw(Decimal('500.000'), 'first withdraw', day00)
# after 30 days: 30 days have passed. Let us now compute the outstanding
# and check the total due.
day30 = day00 + timedelta(days=30)
self.assertEqual(self.cm.compute_outstanding(day30), Decimal('514.39'))
def test_compute_outstanding_case_03(self):
# additional: case 03
# on day 1: draws $500
day00 = datetime.now()
self.cm.withdraw(Decimal('500.000'), 'first withdraw', day00)
# after 25 days: he repays the amount (with $100 extra)
day25 = day00 + timedelta(days=25)
self.cm.pay(Decimal('600.000'), 'first payment', day25)
# after 27 days: he draws $150 more
day27 = day00 + timedelta(days=27)
self.cm.withdraw(Decimal('150.000'), 'second withdraw', day27)
# after 30 days: 30 days have passed. Let us now compute the outstanding
# and check the total due.
day30 = day00 + timedelta(days=30)
self.assertEqual(self.cm.compute_outstanding(day30), Decimal('50.00'))
def test_withdrawal_on_excess_payment(self):
self.assertEqual(self.cm.pay(Decimal('2000.00'), 'making extra payment'), None)
self.assertEqual(self.cm.withdraw(Decimal('2500.00'), 'withdrawing more than the limit'), None)
# check the due
self.assertEqual(self.cm.get_current_due(), Decimal('500.000'))
