Mockito @InjectMocks 不适用于相同类型的字段 [英] Mockito @InjectMocks doesn't work for fields with same type

问题描述

我很惊讶地发现以下简单的代码示例不适用于所有 Mockito 版本 > 1.8.5

I was very surprised to find out that following simple code example doesn't work for all Mockito versions > 1.8.5

@RunWith(MockitoJUnitRunner.class)
public class MockitoTest {

    @Mock(name = "b2")
    private B b2;

    @InjectMocks
    private A a;

    @Test
    public void testInjection() throws Exception {
        assertNotNull(a.b2); //fails
        assertNull(a.b1); //also fails, because unexpectedly b2 mock gets injected here
    }

    static class A{
        private B b1;
        private B b2;
    }

    interface B{}
}

在 javadocs (http://docs.mockito.googlecode.com/hg/latest/org/mockito/InjectMocks.html)有一句话:

In javadocs (http://docs.mockito.googlecode.com/hg/latest/org/mockito/InjectMocks.html) there is a quote:

注意 1:如果您有相同类型(或相同擦除)的字段，则为最好用匹配字段命名所有 @Mock 注释字段，否则 Mockito 可能会感到困惑并且不会发生注入.

Note 1: If you have fields with the same type (or same erasure), it's better to name all @Mock annotated fields with the matching fields, otherwise Mockito might get confused and injection won't happen.

这是否意味着如果我有多个具有相同类型的字段，我不能只模拟其中一个，而是应该为具有相同类型的 ALL 字段定义 @Mock?它是已知的限制吗?是否有任何原因尚未修复?通过字段名称匹配 @Mock 应该很简单，不是吗?

Does it mean that if I have several fields with same type I can't mock ONLY ONE of them but rather should define @Mock for ALL fields with same type? Is it known limitation and is there any reason why it wasn't fixed yet? It should be straightforward to match @Mock by fields names, isn't it?

推荐答案

看来 Mockito 使用了 他们的JavaDoc

It appears Mockito uses an algorithm described in their JavaDoc

如果我理解正确，它将首先按类型排序(在这种情况下只有 1 B)，然后按名称排序(这里没有更改).它最终将使用 OngoingInjector 接口实现注入，这似乎是搜索第一个字段并注入它.

If I understand correctly, it will first sort on type (in this case only 1 B) and then sort on name (no changes here). It will finally inject using the OngoingInjector interface implementation, which appears to search for the first field and inject it.

由于您只定义了 1 个 B 并且 Mock 中有 B 的 2 个字段，因此它将看到第一个实例与该字段的匹配并停止.这是因为 NameBasedCandidateFilter.因此它将停止过滤并直接注入.如果您创建多个相同类型的模拟，它们将按名称排序并相应地注入.

Since you only have 1 B defined and there are 2 fields of B in the Mock, it will see the match of the first instance to the field and stop. This is because mocks.size() == 1 in NameBasedCandidateFilter . Therefore it will stop filtering and inject it directly. If you create multiple mocks of the same type, they will get sorted on Name and injected accordingly.

当我创建多个特定类型的模拟(但少于字段数量)时，我能够让它工作.

I was able to get it work when I created multiple mocks (but less than the number of fields) of a specific type.

@RunWith(MockitoJUnitRunner.class)
public class MockitoTest {

    @Mock(name = "b2")
    private B b2;

    @Mock(name = "b3")
    private B b3;

    @InjectMocks
    private A a;

    @Test
    public void testInjection() {
        System.out.println(this.a);
    }

    static class A {

        private B b1;

        private B b2;

        private B b3;
    }

    interface B {
    }
}

这将正确地将 b2 注入 a.b2 并将 b3 注入 a.b3 而不是 a.b1 和 a.b2(在 A 中定义的前 2 个字段).

This will correctly inject b2 into a.b2 and b3 into a.b3 instead of a.b1 and a.b2 (the first 2 fields that are defined in A).

您始终可以在他们的存储库中留下一个 GitHub 问题，并对注入过滤算法进行增强或更改，以便查看.

You can always leave a GitHub issue on their repository with an enhancement or change on the injection filtering algorithm in order to be looked at.

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