问题描述

是否可以以通用方式拦截 mock 上的所有方法调用?

Is it possible to intercept all method invocations on a mock in a generic way?

示例

给定一个供应商提供的类，例如:

Given a vendor provided class such as:

public class VendorObject {

    public int someIntMethod() {
        // ...
    }

    public String someStringMethod() {
        // ...
    }

}

我想创建一个模拟，将 all 方法调用重定向到另一个具有匹配方法签名的类:

I would like to create a mock that re-directs all method calls to another class where there are matching method signatures:

public class RedirectedToObject {

    public int someIntMethod() {
        // Accepts re-direct
    }

}

Mockito 中的 when().thenAnswer() 构造似乎符合要求，但我找不到将任何方法调用与任何参数匹配的方法.无论如何，InvocationOnMock 肯定给了我所有这些细节.有没有通用的方法来做到这一点?看起来像这样的东西，其中 when(vo.*) 被替换为适当的代码:

The when().thenAnswer() construct in Mockito seems to fit the bill but I cannot find a way to match any method call with any args. The InvocationOnMock certainly gives me all these details anyway. Is there a generic way to do this? Something that would look like this, where the when(vo.*) is replaced with appropriate code:

VendorObject vo = mock(VendorObject.class);
when(vo.anyMethod(anyArgs)).thenAnswer(
    new Answer() {
        @Override
        public Object answer(InvocationOnMock invocation) {

            // 1. Check if method exists on RedirectToObject.
            // 2a. If it does, call the method with the args and return the result.
            // 2b. If it does not, throw an exception to fail the unit test.

        }
    }
);

在供应商类周围添加包装器以简化模拟不是一种选择，因为:

Adding wrappers around the vendor classes to make mocking easy is not an option because:

1. 现有代码库太大.
2. 对性能要求极高的应用程序的一部分.

推荐答案

我想你想要的是:

VendorObject vo = mock(VendorObject.class, new Answer() {
    @Override
    public Object answer(InvocationOnMock invocation) {

        // 1. Check if method exists on RedirectToObject.
        // 2a. If it does, call the method with the args and return the
        // result.
        // 2b. If it does not, throw an exception to fail the unit test.

    }
});

当然，如果你想经常使用这种方法，Answer 不需要匿名.

Of course, if you want to use this approach frequently, no need for the Answer to be anonymous.

来自 文档:这是一个非常高级的功能，通常你不需要它来编写体面的测试.但是在使用遗留系统时它会很有帮助."听起来像你.

From the documentation: "It's quite advanced feature and typically you don't need it to write decent tests. However it can be helpful when working with legacy systems." Sounds like you.

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