I think there are 3 distinct behaviors here we care about.  They're all pretty easy to spec so I think it's worth doing so:

* The deprecation warning should be raised.
* Referencing the deprecated constant should return a reference to the new name for the constant.
* When a different missing constant is referenced it should raise the normal error. (otherwise, we'd be all green if you removed the `super` call which is really important).

I wrote similar specs in [this commit](https://github.com/rspec/rspec-core/commit/adfb5c091a0c44a4be0cebaebb3f55474c7ced69#diff-9e8b3a5e55f6e07759f2414ad0f96f9bR89) that you can probably base yours on.