Why does this Assert fail?

Question

IEnumerable<ReportReceipt> expected = new List<ReportReceipt>() { new ReportReceipt("fileName1","Hash1","some comments1") }; IEnumerable<ReportReceipt> actual = new List<ReportReceipt>() { new ReportReceipt("fileName1","Hash1","some comments1") }; Assert.IsTrue(expected.SequenceEqual(actual)); 

I am running MSTest with VS 2008.

Answer 1

SequenceEqual determines whether two sequences are equal by comparing elements using the default equalizer for their type.

If you have not overloaded Equals and GetHashCode in your class, the equality check of the backup object will fail because the sequences contain two different objects.

Answer 2

Presumably because ReportReceipt does not override Equals - therefore it only compares links, and they are unequal.

Replace Equals and GetHashCode respectively, and it should work fine.

Answer 3

Have you overloaded the equality operator for ReportReceipt? Is the SequenceEqual method not testing to locate ReportReceipt in memory, not the contents of an object? Overriding peers and GetHashCode should solve your problem.

Add the following to ReportReceipt:

 public override bool Equals(object obj) { if (obj == null || obj.GetType() != this.GetType) return false; ReportReceipt other = (ReportReceipt)obj; return this.FileName.Equals(other.FileName) && this.Hash.Equals(other.Hash); } 

Answer 4

You are comparing two different instances of reference objects — this way they will not be equal unless you implement Equals in a type to check property values ​​instead of links.

To make this easier, use CollectionAssert.AreEquivalent() .

Answer 5

If you want to use your own resolver to determine equality, you can use the overload of this method described in MSDN

Basically, you will pass the IEqualityComparer<TSource> as parameter, which will be used to compare the elements.