当我结合构造函数注入(子类)和属性注入(父类)时，@InjectMocks 给我 null [英] @InjectMocks gives me null when i combine constructor injection(child class) and property injection(parent class)

问题描述

我有一个带有注入属性的摘要.这是由一个子类扩展的，其中注入是通过构造函数完成的.在单元测试中，@InjectMocks 为抽象类中注入的属性提供 null.

I have an abstract with an injected property. This is extended by a child class where the injection is done via constructor. In the Unit test, the @InjectMocks gives null for the property injected in the abstract class.

查看下面的代码.

我想了解为什么在这种特定情况下 @InjectMocks 不知道从抽象类中注入属性.有人可以帮我理解吗?非常感谢！！！

I would like to understand why in this specific situation the @InjectMocks does not know to inject the property from the abstract class. Can anybody help me to understand? Thanks a lot!!!

如果子类和父类都使用属性注入，我的单元测试就没有问题.

If both child and parent class uses property injection, my unit test works without problems.

public abstract class AbstractClass
{
  @Inject
  private D d;
  ...  
}

@RequestScoped
public class ConcreteClass extends AbstractClass
{ 
  private A a;
  private B b;
  private C c;

  @Inject
  public ConcreteClass(A a, B b, C c)
  {
    this.a = a;
    this.b = b;
    this.c = c;
  }

  /**
   * CDI, no arguments constructor.
   */
  public ConcreteClass()
  {
    // CDI constructor
  }
}

@RunWith(Theories.class)
public class ConcreteClassTest
{
  @Mock
  D d;

  @Mock
  A a; 

  @InjectMocks
  ConcreteClass concreteClass;  

 @Before
  public void setUp() throws Exception
  {
   ...
    MockProvider.setMockForClass(A.class, a);
    MockProvider.setMockForClass(D.class, d);
    ...
  }   

  @Theory
  public void testMethod()     
  {
    ...
    concreteClass.methodXXX();
    //here if i inspect the concreteClass i see that the attribute "a" has    value and attribute "d" is null.
    ...
  }  

}

推荐答案

来自 mockito 文档:
https://static.javadoc.io/org.mockito/mockito-core/3.0.0/org/mockito/InjectMocks.html

From the mockito documentation:
https://static.javadoc.io/org.mockito/mockito-core/3.0.0/org/mockito/InjectMocks.html

构造函数注入；选择最大的构造函数，然后使用仅在测试中声明的模拟来解析参数.如果使用构造函数成功创建了对象，则 Mockito 不会尝试其他策略.Mockito 决定不破坏具有参数构造函数的对象.

Constructor injection; the biggest constructor is chosen, then arguments are resolved with mocks declared in the test only. If the object is successfully created with the constructor, then Mockito won't try the other strategies. Mockito has decided to no corrupt an object if it has a parametered constructor.

因为你的构造函数只有 A、B、C，mockito 没有处理 D.
(不考虑属性或字段注入)

As your constructor only has A, B, C mockito does not take care of D.
(Property or Field injection are not considered)

您可以更改构造函数，使其具有全部 4 个值并将 D 传递给超类.

You could change your Constructor so that it has all 4 values and passes on D to the superclass.

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