I really wish I could utter some rude marks to express my feeling, as probably some lack in the kata's description made me stuck for days sitting in front of the computer and wasting time, trying to figure out what that bloody "Before method called invokone P1" means.
Could you just friendly just inform me how am I supposed to know what you mean by "P1"?????
It could be anything, and non of them helped me worked out my problem.
But it was all because the vague description of the findMethod() method, where you just wrote "should return a function one can invoke with arguments of the same type", and what is that supposed to mean? I didn't see anything informing me that a method obtained by findMethod() should do exactly the same thing the moment it is overridden by another one or simply removed from the generic function, regardless of what operations have been casted on the generic function since then! You haven't mentioned that also the before and after methods should be invoked on a call on a method retrived using findMethod()! All I see is "invoke with arguments of the same type"! Even if you can't modify the kata description now, shouldn't you be just nice enough to explain it a bit here in the discussion? Not to mention that nothing was said about that removeMethod() should also support chain calling! Nothing!
I know you have said that you must have left things vague in some instances, but such a big failure like this - I can't just ignore it, it costed me loads of time! All that wast of time here is just because some stupid lacks in expression, and the explainations in the discussion - as you have promised - is nowhere to be seen.
And the most vague thing I see, is probably the annoying test cases. Most of the test case descriptions simply can't tell anything, like the "P1" case, as I have mentioned before.
Matbe there is nobody left on this site to have scarcely a look at all these, but - I just want everybody who is willing to see others' opinions to know: This kata stinks!

Sorry to bother you guys, the problem is solved.
I just simple forgot to trim the spaces at the end of the returned string.
Thank you all.

                 +--+
                 |  |
                 |  |
+----------------+  |
|                   |
|                   |
+-------------------+
+-------------------+
|                   |
|                   |
|  +----------------+
|  |                 
|  |                 
+--+
                 +--+
                 |  |
                 |  |
+----------------+  |
|                   |
|                   |
+-------------------+
+-------------------+
|                   |
|                   |
|  +----------------+
|  |
|  |
+--+

Sorry, it actually looks like this, though I still can't find any difference.

Is there something wrong whis this kata?
My submit results always looks like this:
It returned:
+--+
| |
| |
+----------------+ |
| |
| |
+-------------------+
+-------------------+
| |
| |
| +----------------+
| |
| |
+--+ but the expected value is:
+--+
| |
| |
+----------------+ |
| |
| |
+-------------------+
+-------------------+
| |
| |
| +----------------+
| |
| |
+--+
I just wanna know what's up? Don't they look exactly the same?