Python单元测试：解决Mock异常方法调用计数不准确的问题

import json
import logging
# 假设 GoogleCloudError 和 Blob 类定义在其他地方或通过外部库引入
# 这里为了演示，我们简化它们
class GoogleCloudError(Exception):
    pass

class Blob:
    def __init__(self, name, bucket):
        self.name = name
        self.bucket = bucket

    def upload_from_string(self, data, content_type):
        """模拟上传文件到云存储"""
        if "error" in data: # 模拟特定条件抛出异常
            raise GoogleCloudError("Simulated upload error")
        print(f"Uploading {len(data)} bytes to {self.bucket}/{self.name}")
        return True

class UploadService:
  def upload(self, name, data, gcs_bucket):
    try:
      gcs_blob = Blob(name, gcs_bucket)
      gcs_blob.upload_from_string(data=json.dumps(data), content_type="application/json")
      return "Upload successful"
    except GoogleCloudError as e:
      logging.exception("Error uploading file")
      return f"Upload failed: {e}"

import unittest
from unittest.mock import patch, MagicMock
from upload_service import UploadService, GoogleCloudError, Blob # 导入相关类
import json

class TestUploadService(unittest.TestCase):
  def test_upload_failure(self):
    us = UploadService()
    test_data = {"key": "value"}
    test_name = "test_file"
    test_bucket = "test_bucket"

    with patch("upload_service.Blob") as mocked_blob_class:
      # 配置模拟的 Blob 实例，使其 upload_from_string 方法抛出异常
      gcs_blob_instance = mocked_blob_class.return_value
      gcs_blob_instance.upload_from_string.side_effect = GoogleCloudError("Google Cloud error")

      result = us.upload(test_name, test_data, test_bucket)

      # 期望的结果：upload_from_string 被调用了一次
      # 错误的断言方式：对模拟类对象进行断言
      self.assertEqual(1, mocked_blob_class.upload_from_string.call_count) # 错误！

      # 验证错误处理逻辑
      self.assertIn("Upload failed", result)
      self.assertIn("Google Cloud error", result)

import unittest
from unittest.mock import patch, MagicMock
from upload_service import UploadService, GoogleCloudError, Blob
import json

class TestUploadService(unittest.TestCase):
  def test_upload_failure_fixed(self): # 修改方法名以示区分
    us = UploadService()
    test_data = {"key": "value"}
    test_name = "test_file"
    test_bucket = "test_bucket"

    with patch("upload_service.Blob") as mocked_blob_class:
      # 配置模拟的 Blob 实例，使其 upload_from_string 方法抛出异常
      gcs_blob_instance = mocked_blob_class.return_value
      gcs_blob_instance.upload_from_string.side_effect = GoogleCloudError("Google Cloud error")

      result = us.upload(test_name, test_data, test_bucket)

      # 正确的断言方式：对模拟实例的 upload_from_string 方法进行断言
      self.assertEqual(1, gcs_blob_instance.upload_from_string.call_count) # 正确！

      # 验证错误处理逻辑
      self.assertIn("Upload failed", result)
      self.assertIn("Google Cloud error", result)