从字典调用的python中的模拟函数

Question

我对下面的代码有疑问。我想模拟不同文件中的函数以在 FUNCTION_MAPPING 部分进行单元测试。

import module.module2 as module_name

FUNCTION_MAPPING = {
1: module_name.foo,
2: module_name.foo2,
3: module_name.foo3
}

def my_func(number):
    function_call = FUNCTION_MAPPING[number]
    result = function_call()
    return result

由于某种原因，我无法模拟这些功能。我已经尝试了我所知道的所有可能的方法。如果可能的话，我不想更改上面的代码。

foo、foo2 和 foo3 内部代码可以是任何 print(1)、print(2) 等

单元测试代码：

@patch("module_of_the_code_above.module_name.foo",return_value="Test")
def test_my_func(self,mocked_foo):
    result = my_func(1)
    nose_tools.assert_equal(result,"Test")

Answer 1

如果你使用 MagicMock，简单的两个选项：

这种情况的问题是，当您导入模块时，会创建带有查找的字典并引用“module_name.foo”，因此全局级别的任何修补/模拟都不会影响该显式映射，您必须在该结构上替换/包装它。

....

# in you test manually replace the function mapping with either new
# functions you define, but I prefer MagicMock as it allows you to get
# all kinds of goodies.
# This is necessary as the dict for the function lookup is probably already
# initialize before any mocking can take place (as you include the module)
# and so even patching the function globally will not affect that lookup

# You can use MagicMock so that your original function is not used..
FUNCTION_MAPPING['1'] = mock.MagicMock()
FUNCTION_MAPPING['2'] = mock.MagicMock()
FUNCTION_MAPPING['3'] = mock.MagicMock()

# Or

# if you just want to spy/keep stats but still call the original function, you will 
# need to do something like 
FUNCTION_MAPPING['1'] = mock.Mock(wraps=FUNCTION_MAPPING['1')

# then you can all the great things that you can do with mock. 
assert FUNCTION_MAPPING['1'].call_counts == 3

PS：没有时间测试/审查 this 的确切语法，但希望这能指引您正确的方向。

Answer 2

您应该分配函数（不带括号）而不是函数的结果 - {1: func}

def hello():
    print('Hello!')

def text(text):
    print(text)

function_map = {
    1: hello,
    2: text
}

func1 = function_map[1]
func1()

func2 = function_map[2]
func2('ABC123')

输出：

Hello!
ABC123

使用导入时：

import math

function_map = {
    'factorial': math.factorial,
    'gcd': math.gcd
}

func1 = function_map['factorial']
print(func1(5))

func2 = function_map['gcd']
print(func2(5, 25))