Java 如何在不运行方法的情况下模拟方法调用和返回值？
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How to mock method call and return value without running the method?
提问by Sorona
Consider the following method:
考虑以下方法：
public boolean isACertainValue() {
if(context.getValueA() != null && context.getValueA().toBoolean() == true) {
if(context.getType() != null && context.getType() == ContextType.certainType) {
return true;
}
}
return false;
}
I did not write this code, it is ugly as hell, it is totally overcomplicated but I have to work with it.
这段代码不是我写的，它丑得要命，它完全过于复杂，但我必须使用它。
Now I want to test a method that relies on a call to this method.
现在我想测试一个依赖于调用这个方法的方法。
I thought I could deal with this by:
我以为我可以通过以下方式处理这个问题：
Mockito.when(spy.isACertainValue()).thenReturn(true);because that's the case I want to test.
Mockito.when(spy.isACertainValue()).thenReturn(true);因为这就是我想要测试的情况。
But it doesn't work as it is still calling the method-body :/
但它不起作用，因为它仍在调用方法体：/
I get nullpointers or rather I get something along the lines of
我得到了空指针，或者更确切地说我得到了一些类似的东西
misusing.WrongTypeOfReturnValue; Boolean cannot be returned by getValueA(). getValueA() should return ValueA
misusing.WrongTypeOfReturnValue; getValueA() 不能返回布尔值。getValueA() 应该返回 ValueA
So I tried (as a workaround) to do:
所以我尝试（作为一种解决方法）这样做：
Mockito.when(contextMock.getValueA()).thenReturn(new ValueA());and
Mockito.when(contextMock.getType()).thenReturn(ContextType.certainType);
Mockito.when(contextMock.getValueA()).thenReturn(new ValueA());和
Mockito.when(contextMock.getType()).thenReturn(ContextType.certainType);
but then I get a nullpointer that I cant seem to be able to debug.
但是后来我得到了一个我似乎无法调试的空指针。
So, how is it done right in this case?
那么，在这种情况下它是如何正确完成的呢？
采纳答案by Tunaki
When you are invoking
当你调用
Mockito.when(spy.isCertainValue()).thenReturn(true);
the method isCertainValue()is getting called here. This is how Java works: to evaluate the argument of Mockito.when, the result of spy.isCertainValue()must be evaluated so the method must be called.
该方法isCertainValue()在这里被调用。这就是 Java 的工作方式：要评估 的参数Mockito.when，spy.isCertainValue()必须评估的结果，因此必须调用该方法。
If you don't want that to happen, you can use the following construct:
如果您不希望发生这种情况，可以使用以下构造：
Mockito.doReturn(true).when(spy).isCertainValue();
This will have the same mocking effect but the method won't be called with this.
这将具有相同的模拟效果，但不会用 this 调用该方法。
回答by Chris Sim
This code is correct:
这段代码是正确的：
Mockito.when(contextMock.getType()).thenReturn(ContextType.certainType);
But you are getting NullPointerException because you didn't define the Mocking value that should be defines, well I'm using Spring, in my context file when I define @Autowiredbean I define it this way:
但是你得到 NullPointerException 因为你没有定义应该定义的 Mocking 值，我正在使用 Spring，在我定义@Autowiredbean 的上下文文件中我这样定义它：
<bean id="contextMock" class="org.mockito.Mockito" factory-method="mock">
<constructor-arg value="com.example.myspringproject.bean.ContextMock" />
</bean>
