使用依赖注入模拟 C++ 类 [英] Mocking C++ classes with dependency injection

问题描述

假设您正在测试类 A，它有一个 依赖注入B 的 a> 具有 C 的依赖注入.
所以你模拟 B 但它拥有的唯一构造函数需要注入C，所以你是否也必须模拟 C 并将模拟的 C 注入模拟的 B 并且只然后将其注入到 A?
如果你有 5 个连续的依赖项怎么办?

Say you're testing class A and it has a dependency injection of B which has a dependency injection of C.
So you mock B but the only constructor it has requires an injection of C, so do you have to mock C as well and inject the mocked C into the mocked B and only then inject it to A?
What if you have 5 consecutive dependancies?

有什么选择?

我使用 Google Mock，所以具体的答案也会有所帮助.

I use Google Mock, so a specific answer would help as well.

推荐答案

在这种情况下你应该通过指针而不是通过引用来注入，那么你可以传递一个 NULL 指针.假设您的对象确实是模拟对象而不是假对象，这将起作用，因此它对注入的对象没有真正的依赖关系.

In this case you should inject by pointer and not by reference, then you could pass a NULL pointer. This would work assuming you're object is indeed a mock and not a fake object, therefore it has no real dependency on the injected object.

对于 boost::shared_ptr 您可以执行以下操作:

For boost::shared_ptr you could do the following:

boost::shared_ptr<C> null_c_ptr;
MockB mock_b(null_c_ptr);

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