如何模拟具有未绑定方法的类？例如，此类有@classmethod和@staticmethod：
class Calculator(object):
def __init__(self, multiplier):
self._multiplier = multiplier
def multiply(self, n):
return self._multiplier * n
@classmethod
def increment(cls, n):
return n + 1
@staticmethod
def decrement(n):
return n - 1
calculator = Calculator(2)
assert calculator.multiply(3) == 6
assert calculator.increment(3) == 4
assert calculator.decrement(3) == 2
assert Calculator.increment(3) == 4
assert Calculator.decrement(3) == 2
上面几乎描述了我的问题。以下是一个工作示例，演示了我尝试过的事情。
班级Machine包含Calculator的实例。我将使用模拟Machine来测试Calculator。为了演示我的问题，Machine通过Calculator的实例和Calculator类调用未绑定的方法：
class Machine(object):
def __init__(self, calculator):
self._calculator = calculator
def mult(self, n):
return self._calculator.multiply(n)
def incr_bound(self, n):
return self._calculator.increment(n)
def decr_bound(self, n):
return self._calculator.decrement(n)
def incr_unbound(self, n):
return Calculator.increment(n)
def decr_unbound(self, n):
return Calculator.decrement(n)
machine = Machine(Calculator(3))
assert machine.mult(3) == 9
assert machine.incr_bound(3) == 4
assert machine.incr_unbound(3) == 4
assert machine.decr_bound(3) == 2
assert machine.decr_unbound(3) == 2
上面的所有功能代码都可以正常工作。接下来是不起作用的部分。
我创建了一个Calculator模拟器，用于测试Machine：
from mock import Mock
def MockCalculator(multiplier):
mock = Mock(spec=Calculator, name='MockCalculator')
def multiply_proxy(n):
'''Multiply by 2*multiplier instead so we can see the difference'''
return 2 * multiplier * n
mock.multiply = multiply_proxy
def increment_proxy(n):
'''Increment by 2 instead of 1 so we can see the difference'''
return n + 2
mock.increment = increment_proxy
def decrement_proxy(n):
'''Decrement by 2 instead of 1 so we can see the difference'''
return n - 2
mock.decrement = decrement_proxy
return mock
在下面的单元测试中，绑定的方法使用了MockCalculator，正如我所希望的那样。但是，对Calculator.increment()和Calculator.decrement()的调用仍使用Calculator：
import unittest
class TestMachine(unittest.TestCase):
def test_bound(self):
'''The bound methods of Calculator are replaced with MockCalculator'''
machine = Machine(MockCalculator(3))
self.assertEqual(machine.mult(3), 18)
self.assertEqual(machine.incr_bound(3), 5)
self.assertEqual(machine.decr_bound(3), 1)
def test_unbound(self):
'''Machine.incr_unbound() and Machine.decr_unbound() are still using
Calculator.increment() and Calculator.decrement(n), which is wrong.
'''
machine = Machine(MockCalculator(3))
self.assertEqual(machine.incr_unbound(3), 4) # I wish this was 5
self.assertEqual(machine.decr_unbound(3), 2) # I wish this was 1
所以我尝试修补Calculator.increment()和Calculator.decrement()：
def MockCalculatorImproved(multiplier):
mock = Mock(spec=Calculator, name='MockCalculatorImproved')
def multiply_proxy(n):
'''Multiply by 2*multiplier instead of multiplier so we can see the difference'''
return 2 * multiplier * n
mock.multiply = multiply_proxy
return mock
def increment_proxy(n):
'''Increment by 2 instead of 1 so we can see the difference'''
return n + 2
def decrement_proxy(n):
'''Decrement by 2 instead of 1 so we can see the difference'''
return n - 2
from mock import patch
@patch.object(Calculator, 'increment', increment_proxy)
@patch.object(Calculator, 'decrement', decrement_proxy)
class TestMachineImproved(unittest.TestCase):
def test_bound(self):
'''The bound methods of Calculator are replaced with MockCalculator'''
machine = Machine(MockCalculatorImproved(3))
self.assertEqual(machine.mult(3), 18)
self.assertEqual(machine.incr_bound(3), 5)
self.assertEqual(machine.decr_bound(3), 1)
def test_unbound(self):
'''machine.incr_unbound() and Machine.decr_unbound() should use
increment_proxy() and decrement_proxy(n).
'''
machine = Machine(MockCalculatorImproved(3))
self.assertEqual(machine.incr_unbound(3), 5)
self.assertEqual(machine.decr_unbound(3), 1)
即使在修补之后，未绑定的方法也需要Calculator的实例作为参数：
TypeError：必须使用Calculator实例作为第一个参数调用未绑定方法increment_proxy（）（改为使用int实例）
如何模拟类方法Calculator.increment()和静态方法Calculator.decrement()？
答案 0 :(得分：5)
你正在修补错误的对象。您必须修补Calculator课程中的Machine，而不是普通Calculator课程。阅读它here。
from mock import patch
import unittest
from calculator import Calculator
from machine import Machine
class TestMachine(unittest.TestCase):
def my_mocked_mult(self, multiplier):
return 2 * multiplier * 3
def test_bound(self):
'''The bound methods of Calculator are replaced with MockCalculator'''
machine = Machine(Calculator(3))
with patch.object(machine, "mult") as mocked_mult:
mocked_mult.side_effect = self.my_mocked_mult
self.assertEqual(machine.mult(3), 18)
self.assertEqual(machine.incr_bound(3), 5)
self.assertEqual(machine.decr_bound(3), 1)
def test_unbound(self):
'''Machine.incr_unbound() and Machine.decr_unbound() are still using
Calculator.increment() and Calculator.decrement(n), which is wrong.
'''
machine = Machine(Calculator(3))
self.assertEqual(machine.incr_unbound(3), 4) # I wish this was 5
self.assertEqual(machine.decr_unbound(3), 2) # I wish this was 1
答案 1 :(得分：0)
一种方法是
def test_increment(mocker):
mocker.patch.object(Calculator, attribute='increment', return_value=10)
...actual test code...
答案 2 :(得分：0)
我只是做了一些可以转化为你的案例的事情：
class BaseFile(UidMixin, BaseModel):
__metaclass__ = ABCMeta
upload_directory = ""
def generate_filename(self, filename):
return "uploads/"
class SeamlessFile(BaseFile):
def generate_filename(self, filename):
return os.path.join("seam/", basename(filename))
actual_file = models.FileField(
default=None, null=True, blank=True,
upload_to=generate_filename,
)
class FrontEndAuditFile(SeamlessFile):
def generate_filename(self, filename):
print("FrontEndAuditFile -> generate_filename")
return os.path.join("fro/", basename(filename))
然后，在您的测试中，像这样简单的事情：
class Calculator_Mock(object):
def __init__(self, multiplier):
... # add whatever you need here
def multiply(self, n):
... # add whatever you need here
@classmethod
def increment(self, n):
... # add whatever you need here
答案 3 :(得分：-1)
C＃，Java和C ++程序员倾向于过度使用Python中的类和静态方法。 Pythonic方法是使用模块函数。
首先，这是测试中的重构软件，方法increment()和decrement()作为模块函数。界面确实改变了，但功能是相同的：
# Module machines
class Calculator(object):
def __init__(self, multiplier):
self._multiplier = multiplier
def multiply(self, n):
return self._multiplier * n
def increment(n):
return n + 1
def decrement(n):
return n - 1
calculator = Calculator(2)
assert calculator.multiply(3) == 6
assert increment(3) == 4
assert decrement(3) == 2
class Machine(object):
'''A larger machine that has a calculator.'''
def __init__(self, calculator):
self._calculator = calculator
def mult(self, n):
return self._calculator.multiply(n)
def incr(self, n):
return increment(n)
def decr(self, n):
return decrement(n)
machine = Machine(Calculator(3))
assert machine.mult(3) == 9
assert machine.incr(3) == 4
assert machine.decr(3) == 2
向模拟increment_mock()和decrement_mock()添加函数increment()和decrement()：
from mock import Mock
import machines
def MockCalculator(multiplier):
mock = Mock(spec=machines.Calculator, name='MockCalculator')
def multiply_proxy(n):
'''Multiply by 2*multiplier instead of multiplier so we can see the
difference.
'''
return 2 * multiplier * n
mock.multiply = multiply_proxy
return mock
def increment_mock(n):
'''Increment by 2 instead of 1 so we can see the difference.'''
return n + 2
def decrement_mock(n):
'''Decrement by 2 instead of 1 so we can see the difference.'''
return n - 2
现在好的部分。修补程序increment()和decrement()用它们的模拟替换它们：
import unittest
from mock import patch
import machines
@patch('machines.increment', increment_mock)
@patch('machines.decrement', decrement_mock)
class TestMachine(unittest.TestCase):
def test_mult(self):
'''The bound method of Calculator is replaced with MockCalculator'''
machine = machines.Machine(MockCalculator(3))
self.assertEqual(machine.mult(3), 18)
def test_incr(self):
'''increment() is replaced with increment_mock()'''
machine = machines.Machine(MockCalculator(3))
self.assertEqual(machine.incr(3), 5)
def test_decr(self):
'''decrement() is replaced with decrement_mock()'''
machine = machines.Machine(MockCalculator(3))
self.assertEqual(machine.decr(3), 1)