模拟函数/对象，并根据输入/条件返回值

Question

我面临以下情况。

我有以下源码

#file:[src/my_module.py]

def order_names(unordered_input: List) -> str: 
   # function that orders a list of names
   ...
       if(is_ID(unordered_input[i])):
           id = unordered_input[i]
           name = get_name_by_id(id)
   ...

def get_name_by_id(id) -> str: 
   # function that returns a name, based on an ID, through a Rest API call
   return make_some_network_call(id)

我想测试函数order_names，我想模拟对get_name_by_id(id)的调用。

假设get_name_by_id(id)会被各种ids多次调用，是否可以创建一个根据输入返回值的mock？

例如：

#file:[test/test_my_module.py]
from unittest import mock
from my_module import order_names

@mock.patch("src.my_module.get_name_by_id", return_value={"3": "Mark", "4": "Kate", "5":"Alfred"})
def test_order_names():
   ordered_names = order_names(["3", "4", "Suzan", "5"])
   assert ordered_names == "Alfred, Kate, Mark, Suzan"

上述测试代码是要实现的行为类型的示例，因为get_name_by_id() 不是dict 返回类型。

干杯！

Answer 1

您基本上需要get_name_by_id 的替代实现，而不仅仅是一个新的返回值。

# Adjust the definition to behave the same when the lookup fails
def get_name_locally(id):
    return {"3": "Mark", "4": "Kate", "5":"Alfred"}.get(id)


def test_order_names():
    with mock.patch('src.my_module.get_name_by_id', get_name_locally):
        ordered_names = order_names(["3", "4", "Suzan", "5"])
    assert ordered_names = "Alfred, Kate, Mark, Suzan"

---

如果get_name_by_id 更复杂，您也可以考虑修补网络调用并让get_name_by_id 按原样运行。

# The same as get_name_locally above, but only because
# get_name_by_id and make_some_network_call are functionally
# identical as far as the question is written.
def network_replacement(id):
    return {"3": "Mark", "4": "Kate", "5":"Alfred"}.get(id)


def test_order_names():
    with mock.patch('src.my_module.make_some_network_call', network_replacement):
        ordered_names = order_names(["3", "4", "Suzan", "5"])
    assert ordered_names = "Alfred, Kate, Mark, Suzan"

现在，当您调用order_names，而它又调用get_name_by_id，make_some_network_call 的替代定义将被get_name_by_id 使用。