** Tags added: v2port
--
NUnit Equality Comparer incorrectly defines equality for Dictionary objects
https://bugs.launchpad.net/bugs/608875
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Developers, which is subscribed to NUnit V2.
Status in NUnit Test Framework: Triaged
Status in NUnit V2 Test Framework: Fix Committed
Bug description:
Using Version 2.5.4
This assertion passes
Assert.That(new Dictionary<int, int> { { 0, 0 }, { 1, 1 }, { 2, 2 }
} == new Dictionary<int, int> { { 0, 0 }, { 2, 2 }, { 1, 1 } });
While this one does not
Assert.AreEqual(new Dictionary<int, int> { { 0, 0 }, { 1, 1 }, { 2,
2 } }, new Dictionary<int, int> { { 0, 0 }, { 2, 2 }, { 1, 1 } });
Order is not preserved in a dictionary, and the standard object.equals for
dictionary objects will ignore the order in which items were added to the
Dictionary.
The offending code in NUnit is in the NUnitEqualityComparer class, line 129
if (x is ICollection && y is ICollection)
return CollectionsEqual((ICollection)x, (ICollection)y);
Since Dictionary implements ICollection, two dictionary objects being compared
will be sent through the CollectionsEqual method, which enforces that the
elements in the ICollection must match by index.
IEnumerator expectedEnum = x.GetEnumerator();
IEnumerator actualEnum = y.GetEnumerator();
int count;
for (count = 0; expectedEnum.MoveNext() && actualEnum.MoveNext();
count++)
{
if (!ObjectsEqual(expectedEnum.Current, actualEnum.Current))
break;
}
To fix it, you'll need to check whether the objects being compared implement
IDictionary before checking to see if they implement ICollection, and handle
them accordingly. I believe you can probably just use object.equals without
providing a specialized equality comparison for Dictionaries.
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