ValueOrderedDict throws IndexError when given equal non-identical keys #2899

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warner · 2017-08-10T01:37:54Z

warner commented

2017-08-10 01:37:54 +00:00

from allmydata.util.dictutil import [ValueOrderedDict](wiki/ValueOrderedDict)
a = (1,2)
b = (1,2)
d = [ValueOrderedDict](wiki/ValueOrderedDict)()
da = 1
db = 1
db = 2

gives:

  File ".../src/allmydata/util/dictutil.py", line 509, in __setitem__
    while (self.l[i][0] is not oldval) or (self.l[i][1] is not key):
IndexError: list index out of range

I found this while trying to improve the test coverage, to exercise the i += 1 statement inside that while loop. I think the only way to reach it is to have keys which are equal but not identical. Python doesn't (currently? always?) consolidate equivalent tuples (although I think it'd be allowed to), which is one way to hit this case.

``` from allmydata.util.dictutil import [ValueOrderedDict](wiki/ValueOrderedDict) a = (1,2) b = (1,2) d = [ValueOrderedDict](wiki/ValueOrderedDict)() da = 1 db = 1 db = 2 ``` gives: ``` File ".../src/allmydata/util/dictutil.py", line 509, in __setitem__ while (self.l[i][0] is not oldval) or (self.l[i][1] is not key): IndexError: list index out of range ``` I found this while trying to improve the test coverage, to exercise the `i += 1` statement inside that `while` loop. I think the only way to reach it is to have keys which are equal but not identical. Python doesn't (currently? always?) consolidate equivalent tuples (although I think it'd be allowed to), which is one way to hit this case.