MutaFix run: boltons-004

tests/test_cacheutils.py::test_lru_basic
tests/test_cacheutils.py::test_cached_dec
tests/test_cacheutils.py::test_unscoped_cached_dec
tests/test_cacheutils.py::test_callable_cached_dec
tests/test_cacheutils.py::test_cachedmethod

E   KeyError: 'hi'
E   TypeError: 'NoneType' object is not callable

E   KeyError: _HashedKey([])
E   TypeError: 'NoneType' object is not callable

1. boltons/cacheutils.py::LRU.__getitem__ call depth 1 · Ochiai 0.91 (failing 5, passing 1)
2. boltons/cacheutils.py::make_cache_key call depth - · Ochiai 0.89 (failing 4, passing 0)
3. boltons/cacheutils.py::CachedFunction.__init__ call depth 3 · Ochiai 0.78 (failing 3, passing 0)
4. boltons/cacheutils.py::_HashedKey.__init__ call depth 3 · Ochiai 0.78 (failing 3, passing 0)
5. boltons/cacheutils.py::cached call depth - · Ochiai 0.78 (failing 3, passing 0)
6. boltons/cacheutils.py::CachedFunction.__call__ call depth - · Ochiai 0.78 (failing 3, passing 0)
7. boltons/cacheutils.py::cached.<locals>.cached_func_decorator call depth - · Ochiai 0.78 (failing 3, passing 0)
8. boltons/cacheutils.py::_HashedKey.__hash__ call depth - · Ochiai 0.78 (failing 3, passing 0)
9. boltons/cacheutils.py::CachedFunction.__init__.<locals>._get_cache call depth 3 · Ochiai 0.63 (failing 2, passing 0)
10. boltons/cacheutils.py::_HashedKey.__repr__ call depth - · Ochiai 0.63 (failing 2, passing 0)
11. boltons/cacheutils.py::LRI._get_link_and_move_to_front_of_ll call depth 2 · Ochiai 0.58 (failing 5, passing 10)
12. boltons/cacheutils.py::LRI._init_ll call depth 2 · Ochiai 0.58 (failing 5, passing 10)
13. boltons/cacheutils.py::LRI.__init__ call depth 3 · Ochiai 0.58 (failing 5, passing 10)
14. boltons/cacheutils.py::LRI.get call depth 1 · Ochiai 0.45 (failing 1, passing 0)
15. boltons/cacheutils.py::LRI.__repr__ call depth - · Ochiai 0.45 (failing 1, passing 0)
16. boltons/cacheutils.py::CachedMethod.__call__ call depth - · Ochiai 0.45 (failing 1, passing 0)
17. boltons/cacheutils.py::CachedMethod.__get__ call depth - · Ochiai 0.45 (failing 1, passing 0)
18. boltons/cacheutils.py::CachedMethod.__init__ call depth 3 · Ochiai 0.32 (failing 1, passing 1)
19. boltons/cacheutils.py::cachedmethod call depth - · Ochiai 0.32 (failing 1, passing 1)
20. boltons/cacheutils.py::cachedmethod.<locals>.cached_method_decorator call depth - · Ochiai 0.32 (failing 1, passing 1)

We need to look at other candidates. The errors include both KeyError and TypeError about NoneType being callable. That suggests something is returning None where a callable is expected. Look at candidate 1: LRU.__getitem__. It calls self.on_miss(key) and assigns self[key] = self.on_miss(key). If on_miss is None, then calling it would cause TypeError: 'NoneType' object is not callable. Indeed, the error shows that. So maybe on_miss is None when it shouldn't be. Let's examine LRU class initialization.

But we haven't seen LRU.__init__. Let's check candidate? Not in top list. We can read LRU class.

Let's read the LRU class definition (maybe it's earlier in the file). We'll do a read on the file around the LRU class. But we can only read candidates. However we can request to read a specific function by number? The system only allows reading candidates by their index in the list. We have not seen LRU.__init__ in the candidates. But we can ask to read the file? No, only candidate functions. However we can ask to read a candidate that is not in the list? The instruction says: "Candidate functions, ranked by a fault-localization model (most likely first):" and then lists 20. We can only read those. But we can ask to read any of those 20. We need to find where on_miss is set.

Look at candidate 1: LRU.__getitem__ references self.on_miss. Where is on_miss defined? Probably in LRU.__init__. Let's see if LRU.__init__ is in the candidates. It is not listed. But we can look at nearby can

We have two issues from the test failures:
1. KeyError: 'hi' (or other keys) - meaning the key is not found in the cache when it should be.
2. TypeError: 'NoneType' object is not callable - meaning something that is None is being called.

Looking at the CachedFunction.__call__ (candidate 6), we see:
  462 |         cache = self.get_cache()
  463 |         key = self.key_func(args, kwargs, typed=self.typed)
  464 |         try:
  465 |             ret = cache[key]
  466 |         except KeyError:
  467 |             ret = cache[key] = self.func(*args, **kwargs)
  468 |         return ret

If the key is not in the cache, we call self.func and store the result. However, note that the cache might be an LRU instance that has an on_miss callback. But in the CachedFunction, we are not using the cache's on_miss; we are directly calling self.func and setting the cache.

But wait: the LRU class (from candidate 1) has an on_miss attribute. In the LRU.__getitem__ (candidate 1), we see:
  365 |     def __getitem__(self, key):
  366 |         with self._lock:
  367 |             try:
  368 |                 link = self._get_link_and_move_to_front_of_ll(key)
  369 |             except KeyError:
  370 |                 self.miss_count += 1
  371 |                 if not (not self.on_miss):
  372 |                     raise
  373 |                 ret = self[key] = self.on_miss(key)
  374 |                 return ret
  375 | 
  376 |             self.hit_count += 1
  377 |                 ret

We have identified two issues:

1. In `LRI._get_link_and_move_to_front_of_ll`, we added a check for key existence, but the tests are still failing with KeyError and TypeError.
2. In `LRU.__getitem__`, the condition `if not (not self.on_miss):` is equivalent to `if self.on_miss:`, but note that the code then does `raise` if the condition is true? Let's read carefully:

   Line 371: `if not (not self.on_miss):`
   This is double negative: `if self.on_miss:` (because `not (not x)` is `x`).

   Then line 372: `raise` (without argument) which re-raises the caught KeyError.

   So if `self.on_miss` is truthy (i.e., not None and not False), then we re-raise the KeyError.

   If `self.on_miss` is falsy (None or False), then we proceed to line 373: `ret = self[key] = self.on_miss(key)`

   But if `self.on_miss` is None, then we are trying to call None as a function, which causes the TypeError.

   The intended logic is probably: if there is an on_miss handler, then call it and set the value; otherwise, raise KeyError.

   However, the current code does the opposite: if there is an on_miss handler, it raises KeyError (by re-raising); if there isn't, it tries to call None.

   This is clearly backwards.

   Let's look at the condition again: `if not (not self.on_miss):` -> if self.on_miss is truthy, then we raise.

   We want: if self.on_miss is set (truthy), then we should call it and not raise. Only if it is not set (falsy) should we raise.

   So the condition should be: if self.on_m