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https://bugs.launchpad.net/bugs/787106

Title:
  EqualConstraint provides inadequate failure information for
  IEnumerables

Status in NUnit Test Framework:
  Triaged
Status in NUnit V2 Test Framework:
  Fix Committed

Bug description:
  When an EqualConstraint compares two IEnumerables and one of them is
  _not_ a collection, the failure reported inadequately. This was called
  to our attention by the following post on nunit-discuss by Gishu
  Pillai but applies more generally than the post indicates.

  Given any CustomType containing a Data (int) property and Name
  (string) property. Equals and ToString overridden

             var someArray = new[] { "A001", "B002", "C003" };
             CollectionAssert.AreEqual( new[] { "x", "Y", "Z" },
  someArray);

   Expected and actual are both <System.String[3]>
   Values differ at index [0]
   Expected string length 1 but was 4. Strings differ at index 0.
   Expected: "x"
   But was:  "A001"

  -------------------------------------------------------------------------------------
  Which is perfect. But now if any of the arguments to AreEqual are a
  result of a Linq query, the failure message drops in readability
             var someArray = new[] { "A001", "B002", "C003" };
             CollectionAssert.AreEqual( new[] { "x", "Y", "Z" },

  someArray.Select(item => item));

   Expected: < "x", "Y", "Z" >
   But was:  <System.Linq.Enumerable
  +WhereSelectArrayIterator`2[System.String,System.String]>

  ----------------------------------------------------------------------------------------
  Even worse
                CollectionAssert.AreEqual( new []{'A', 'B',
  'C'}.Select(item=>item.ToString()),
                                         new [] {"Apple", "Ball",
  "Dog"}.Select(item=> item.Substring(0,1)));

   Expected: <System.Linq.Enumerable
  +WhereSelectArrayIterator`2[System.Char,System.String]>
   But was:  <System.Linq.Enumerable
  +WhereSelectArrayIterator`2[System.String,System.String]>

  if you change the 'C' to 'D' - the test passes as expected.

  I've been trying to write something similar for my custom-adaptation
  of Hamcrest and I think I see what is happening (an are-types-
  compatible check failing for IEnumerable<T> and IEnumerable<K>) .
  However if CollectionAssert.AreEqual internally uses a ToList() or
  ToArray() before processing its arguments, I think the error messages
  would be much more helpful.