的Mockito產生的StackOverflowError當模擬的方法被調用的equals（）/ hashCode（）方法

此示例代碼：的Mockito產生的StackOverflowError當模擬的方法被調用的equals（）/ hashCode（）方法

public final class FooBarTest { 
    @Test 
    public void test() { 
     final Foo foo = mock(Foo.class); 
     when(foo.getBar()).thenReturn(1); 
     new HashSet().add(foo); 
    } 

    private class Foo { 
     @Override 
     public final boolean equals(final Object other) { 
      return getBar() == 0; 
     } 

     public int getBar() { 
      return 0; 
     } 

     @Override 
     public final int hashCode() { 
      return getBar(); 
     } 
    } 
}

產生無限循環並拋出異常：

java.lang.StackOverflowError 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:57) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:43) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor$DispatcherDefaultingToRealMethod.interceptSuperCallable(MockMethodInterceptor.java:119) 
    at de.weltraumschaf.maconha.FooBarTest$Foo$MockitoMock$217383798.getBar(Unknown Source) 
    at de.weltraumschaf.maconha.FooBarTest$Foo.equals(FooBarTest.java:24) 
    at org.mockito.internal.invocation.InvocationMatcher.matches(InvocationMatcher.java:81) 
    at org.mockito.internal.stubbing.InvocationContainerImpl.findAnswerFor(InvocationContainerImpl.java:82) 
    at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:90) 
    at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:32) 
    at org.mockito.internal.handler.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:36) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:57) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:43) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor$DispatcherDefaultingToRealMethod.interceptSuperCallable(MockMethodInterceptor.java:119) 
    at de.weltraumschaf.maconha.FooBarTest$Foo$MockitoMock$217383798.getBar(Unknown Source) 
    at de.weltraumschaf.maconha.FooBarTest$Foo.equals(FooBarTest.java:24) 
    at org.mockito.internal.invocation.InvocationMatcher.matches(InvocationMatcher.java:81) 
    at org.mockito.internal.stubbing.InvocationContainerImpl.findAnswerFor(InvocationContainerImpl.java:82) 
    at org.mockito.internal.handler.MockHandlerImpl.handle(MockHandlerImpl.java:90) 
    at org.mockito.internal.handler.NullResultGuardian.handle(NullResultGuardian.java:32) 
    at org.mockito.internal.handler.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:36) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:57) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor.doIntercept(MockMethodInterceptor.java:43) 
    at org.mockito.internal.creation.bytebuddy.MockMethodInterceptor$DispatcherDefaultingToRealMethod.interceptSuperCallable(MockMethodInterceptor.java:119) 
    at de.weltraumschaf.maconha.FooBarTest$Foo$MockitoMock$217383798.getBar(Unknown Source) 
    at de.weltraumschaf.maconha.FooBarTest$Foo.equals(FooBarTest.java:24) 
    ...

我調試進代碼，並在Mockito的深度迷失。我能看到的唯一情況是equals方法被稱爲正確的。我知道Mockito不存根equals/hashCode/toString。我也很清楚，HashSet調用equals方法來查看它是否已經有相同的元素。但是我無法弄清楚：爲什麼這個循環是無止境的？

使用的Mockito版本是2.8.9和JUnit 4.12。

來源

2017-08-04 Weltraumschaf

可能是由於Mockito使用equals方法本身來驗證它是同一個對象。如果您爲了減少問題而不重寫hash和equals會發生什麼？ Mockito可能不是這方面最好的用例。 –

因爲在調用堆棧有org.mockito.internal.invocation.InvocationMatcher#matches這基本上是
invocation.getMock().equals(candidate.getMock())（與invocation.getMock()是你的嘲笑Foo實例），這導致getBar一個呼叫時，嘲笑這將導致調用equals - >getBar - >模擬 - >equals - >getBar - >等...

來源

2017-08-04 15:26:26 luk2302

的Mockito產生的StackOverflowError當模擬的方法被調用的equals（）/ hashCode（）方法

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