在子类中使用模拟进行 pytest 测试时出现问题

Question

我在尝试模拟调用另一个类的类时遇到问题。 我有三个模块：

树.py

from branch import Branch

class Tree:

    type_of_tree = None
    branches = None

    def __init__(self, type_of_tree, branches = 0, default_leaves = 0):
        self.type_of_tree = type_of_tree
        self.branches = []
        for branch in range(branches):
            self.create_branch(default_leaves)


    def create_branch(self, leaves):
        self.branches.append(Branch(leaves))


    def get_leaves(self):
        return_value = []
        for branch in self.branches:
            return_value.extend(branch.get_leaves())
        return return_value

分支.py

import uuid
from leave import Leave


class Branch:
    leaves = None
    identifier = None

    def __init__(self, leaves=0):
        self.identifier = str(uuid.uuid4())
        self.leaves = []
        for leave in range(leaves):
            self.create_leave()

    def create_leave(self):
        self.leaves.append(Leave())

    def get_leaves(self):
        return_value = []
        for leave in self.leaves:
            return_value.append(leave.get_identifier())
        return return_value

离开.py

import uuid


class Leave:
    identifier = None

    def __init__(self):
        self.identifier = str(uuid.uuid4())

    def get_identifier(self):
        return self.identifier

我正在尝试用以下代码模拟离开课程：

from unittest.mock import patch, MagicMock
from uuid import uuid4

from tree import Tree

FAKE_UUID = str(uuid4())

class TestLeave:


    def test_leave(self):
        with patch('leave.Leave') as mock_leave:
            mock_leave.return_value = MagicMock()
            mock_leave.get_identifier.return_value = FAKE_UUID
            tree = Tree("Pine", 1, 1)
            leaves = tree.get_leaves()
            assert leaves == [FAKE_UUID]

测试失败。我一直在阅读补丁文档但我没有找到相关信息。

Answer 1

我发现我的错误阅读：https://docs.python.org/3.12/library/unittest.mock.html#where-to-patch

模拟休假类的正确方法是从分支导入的类：

from unittest.mock import patch
from uuid import uuid4

from tree import Tree

FAKE_UUID = str(uuid4())


class TestLeave:

    def test_leave(self):
        with patch('branch.Leave') as mock_leave:
            mock_leave.return_value.get_identifier.return_value = FAKE_UUID
            tree = Tree("Pine", 1, 1)
            leaves = tree.get_leaves()
            assert leaves == [FAKE_UUID]

在此示例中，测试工作正常。注意你需要使用mock_leave.return_value获取对象，然后使用get_identifier.return_value = FAKE_UUID模拟返回值