First of all install
mocker:
easy_install mocker
Suppose you need to test withdraw operation in ATM (file
atm.py):
from datetime import datetime
class Atm:
def signin(self, account):
self._account = account
def signout(self):
self._account = None
def withdraw(self, amount):
try:
self._account.withdraw(amount)
self._account.comission(amount * 0.005)
except ValueError:
self._account.comission(amount * 0.001)
return self._account.balance(datetime.now())
A
Mocker instance is used for expectations record/replay. Here is our test (file
mockerexample.py):
import unittest
from datetime import datetime
from mocker import Mocker, ANY, expect
from atm import Atm
class TestAtm(unittest.TestCase):
def setUp(self):
self._mocker = Mocker()
self._mock_account = self._mocker.mock()
self._atm = Atm()
self._atm.signin(self._mock_account)
def tearDown(self):
self._atm.signout()
self._mocker.restore()
self._mocker.verify()
def test_withdraw(self):
# Arrange
self._mock_account.deposit(150)
self._mock_account.withdraw(100)
self._mock_account.comission(0.5)
expect(self._mock_account.balance(ANY))\
.result(49.5)\
.call(lambda d: self.assertTrue(d <= datetime.now()))
self._mocker.replay()
# Act
self._mock_account.deposit(150)
remaining_balance = self._atm.withdraw(100)
# Assert
assert remaining_balance == 49.5
def test_withdraw_insufficient_funds(self):
# Arrange
self._mock_account.deposit(50)
expect(self._mock_account.withdraw(100))\
.throw(ValueError('Insufficient funds'))
self._mock_account.comission(0.1)
expect(self._mock_account.balance(ANY))\
.result(49.9)
self._mocker.replay()
# Act
self._mock_account.deposit(50)
remaining_balance = self._atm.withdraw(100)
# Assert
assert remaining_balance == 49.9
if __name__ == '__main__':
unittest.main()
Run tests:
python mockerexample.py
Read more about mocker
here.
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