Question

此示例代码：

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();
        }
    }
}

产生无限循环并抛出异常：

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)
    ...

我调试了代码并迷失在Mockito的深处。我唯一能看到的是equals方法被称为正确。我知道Mockito没有存根equals / hashCode / toString。我也很清楚，HashSet调用equals方法来查看其中是否已存在相等的元素。但我无法弄清楚：为什么这种循环无止境？

使用过的Mockito版本是2.8.9和JUnit 4.12。

Answer 1

因为在callstack中有org.mockito.internal.invocation.InvocationMatcher#matches基本上是
invocation.getMock().equals(candidate.getMock())（invocation.getMock()是您的模拟Foo实例）会导致对getBar的调用被模拟，导致调用equals - ＆gt; getBar - ＆gt;模拟 - ＆gt; equals - ＆gt; getBar - ＆gt;等...

当在equals（）/ hashCode（）中调用mocked方法时，Mockito会产生StackOverflowError

1 个答案: