Unwrap CGLIB proxy when invoking non-proxied methods in `ReflectionTestUtils`

[drachenpalme]

Overview

We are starting to use Spring AOP and have some issues with existing tests using ReflectionTestUtils.

In one test, a private method of spring-bean A is invoked via ReflectionTestUtils.invokeMethod. This method calls a method of an injected spring-bean B.

With spring-aop in use, this does not work anymore. CGlib will not provide a proxied version of the private method. Therefore the private method of the proxy is invoked, and the proxy does not have the DI-beans present and therefore we encounter a NullPointerException.

Now, my original assumption was that ReflectionTestUtils should handle this (as the setField/getField methods explicitly deal with Spring proxies).

My question is: Is my assumption wrong – and if so, how do we invoke private methods in test – or is this an omission in the ReflectionTestUtils?

Form a user's perspective I would have hoped that ReflectionTestUtils would at least handle the invocation of private methods (there should never be a reason to invoke private methods on a proxy, should there?).

I found issue #18622 which seems to be the point where AOP invocations in setField/getField were considered.

Related Issues

• ReflectionTestUtils should automatically unwrap proxies when accessing fields [SPR-14050] #18622

[sbrannen]

Hi @drachenpalme,

Thanks for raising the issue.

Now, my original assumption was that ReflectionTestUtils should handle this (as the setField/getField methods explicitly deal with Spring proxies).

My question is: Is my assumption wrong – and if so, how do we invoke private methods in test – or is this an omission in the ReflectionTestUtils?

ReflectionTestUtils does not currently handle that scenario, simply because no one ever asked for such support before, and we've never needed it in our own tests.

The way to achieve that now is by invoking AopTestUtils.getUltimateTargetObject() yourself and passing the result of that to ReflectionTestUtils. For example:

ReflectionTestUtils.invokeGetterMethod(AopTestUtils.getUltimateTargetObject(bean), "privateProperty");

Form a user's perspective I would have hoped that ReflectionTestUtils would at least handle the invocation of private methods (there should never be a reason to invoke private methods on a proxy, should there?).

That's correct: there should never be a reason to invoke a private method (or, more specifically, a non-proxied method) on a CGLIB proxy.

I found issue #18622 which seems to be the point where AOP invocations in setField/getField were considered.

That's correct. We'll do something similar for method invocations with ReflectionTestUtils in Spring Framework 6.2, but we'll limit that to non-proxied methods invoked on a CGLIB proxy.

In the interim, please use AopTestUtils.getUltimateTargetObject() manually as mentioned above.

[drachenpalme]

Hi @sbrannen ,

thanks a lot for the quick reaction.
Should anyone else stumble upon this: As there are a lot of places in our code, which are affected by this, we choose to create a drop-in replacement for the ReflectionTestUtils in a different namespace which anticipates your change - so we can simply exchange imports application-wide.

After some further digging: invokeGetterMethod and invokeSetterMethod do seem to have the same problem. We are not affected by this (as we do not use them), yet, consistency-wise, would it be a good idea to adapt them as well?