Unit Test failing when comparing two ILists

Question

I am running some TestMethods thats tests the implementation of a JSON serialiser and when comparing two IList objects before and after the serialisation \ de-serialisation but the comparison is failing.

Model

public class BusinessModel
{
    public int ID { get; set; }
    public string Name { get; set; }
}

Test

IList<BusinessModel> model = new List<BusinessModel>
{
    new BusinessModel { ID = 1, Name = "Test1" },
    new BusinessModel { ID = 2, Name = "Test2" },
    new BusinessModel { ID = 3, Name = "Test3" },
    new BusinessModel { ID = 4, Name = "Test4" }
};

[TestMethod]
public async Task TestSerialiseDeserialiseIsEqual()
{
    ISerialiser serialiser = new Serialiser();

    IList<BusinessModel> deserialisedModel;
    string serialised = string.Empty;

    serialised = await serialiser.SerialiseAsync<IList<BusinessModel>>(model);
    deserialisedModel = await serialiser.DeserialiseAsync<IList<BusinessModel>>(serialised);

    Assert.IsTrue(model.SequenceEqual(deserialisedModel));
}

Results

I have tried a number of test methods detail in this post but all are failing.

Assert.AreEqual(t1.Count(), t2.Count());

IEnumerator<Token> e1 = t1.GetEnumerator();
IEnumerator<Token> e2 = t2.GetEnumerator();

while (e1.MoveNext() && e2.MoveNext())
{
    Assert.AreEqual(e1.Current, e2.Current);
}

passes the collection count items but fails on the first object comparison.

Assert.IsTrue(model.SequenceEqual(deserialisedModel));

fails with Assert.IsTrue failed

CollectionAssert.AreEqual(model.ToArray(),deserialisedModel.ToArray())

fails with Collection.AreEqual failed (Element at index 0 do not match)

CollectionAssert.AreEquivalent(model.ToArray(),deserialisedModel.ToArray())

fails with {"CollectionAssert.AreEquivalent failed. The expected collection contains 1 occurrence(s) of <Helper.Tests.Serialisation.BusinessModel>. The actual collection contains 0 occurrence(s). "}

From checking the objects they look the same

Original

Deserialised Object

Question

What is the best method in comparing IList objects for Unit Testing? Why are my tests failing?

Answer 1

You need to define Equals and GetHashCode for your BusinessModel class. The default Equals implementation is reference equality, and your object references will be different for the items in the two lists.

Alternatively you can create an IEqualityComparer<BusinessModel> which defines equality/hash code and pass that to SequenceEquals.