C++ 単体テストで外部依存関係を模擬するにはどうすればよいですか?

// 使用 Google Mock 创建一个桩：
class MockExternalDependency {
 public:
  MOCK_METHOD(int, Function1, (int a, int b));
};

// 创建桩并用它替换实际的依赖项：
MockExternalDependency mockDependency;
EXPECT_CALL(mockDependency, Function1(1, 2)).WillOnce(Return(3));

// 测试代码：
int result = TestFunction(&mockDependency);
ASSERT_EQ(result, 3);

// 使用 CMocka 创建一个存根：
void external_dependency_stub(int a, int b) {
  // 记录被调用的参数
}

// 设置存根并测试代码：
cmocka_set_stub(external_dependency, external_dependency_stub);
TestFunction();

// 检查存根中记录的调用：
ASSERT_TRUE(cmocka_call_count(external_dependency) > 0);

// 使用依赖项注入进行测试：
void TestFunction(ExternalDependency& dependency) {
  // 使用模拟依赖项调用函数：
  MockExternalDependency mockDependency;
  EXPECT_CALL(mockDependency, Function1(1, 2)).WillOnce(Return(3));
  int result = TestFunction(&mockDependency);
  ASSERT_EQ(result, 3);
}

class MockFileSystem {
 public:
  MOCK_METHOD(FILE*, OpenFile, (const char* filepath));
  MOCK_METHOD(int, ReadFile, (FILE* file, char* buffer, int size));
};

void TestReadFile() {
  MockFileSystem mockFileSystem;
  FILE* mockFile = fopen("mockfile.txt", "w");
  EXPECT_CALL(mockFileSystem, OpenFile("mockfile.txt")).WillOnce(Return(mockFile));
  EXPECT_CALL(mockFileSystem, ReadFile(mockFile, testing::_, _))
      .WillOnce(SetArrayArgument<1>("Hello", 5));

  char buffer[10];
  int result = ReadFile("mockfile.txt", buffer, 10, &mockFileSystem);
  ASSERT_EQ(result, 5);
  ASSERT_STREQ(buffer, "Hello");
}