# DeepEqualityComparer

DeepEqualityComparer checks two objects trees for equality. It implements the .NET Framekwork IComparer interface and can be used everywhere where an IComparer is accepted.

It is mainly intended to be used in unit tests.

Usage

Default

Using the Default Comparere without logging or any special configuration. All Properties are compared.

    [TestFixture]
    public class UseWithNUnit
    {
        private class SomeObject
        {
            public string Text { get; set; }

            public int Number { get; set; }
        }

        [Test]
        public void CompareSomeObjects()
        {
            var so1 = new SomeObject { Number = 12, Text = "abc" };
            var so2 = new SomeObject { Number = 12, Text = "abc" };

            Assert.That(so1, Is.EqualTo(so2).Using(DeepEqualityComparer.Default));
        }
    }

Ignore Indexer

As it is very difficult to compare indexers, DeepEqualityComparer throws an Exception if there is an indexer. To override this behaviour it is possible to ignore indexers.

I'm working on a solution to compare Objects with indexers

    var so1 = new SomeObjectWithIndexer();
    var so2 = new SomeObjectWithIndexer();

    var comparer = DeepEqualityComparer.CreateConfiguration()
            .SetIgnoreIndexer(true)
            .CreateEqualityComparer();

    Assert.That(so1, Is.EqualTo(so2).Using(comparer));

Print comparison result to Console

Using the pre-configured instance DefaultWithConsoleOutput the DeepEqualityComparer prints the result to Console.Out.

        [Test]
        public void CompareWithLogging()
        {
            var so1 = new SomeObject { Number = 12, Text = "abc" };
            var so2 = new SomeObject { Number = 12, Text = "abcd" };

            Assert.That(so1, Is.EqualTo(so2).Using(DeepEqualityComparer.DefaultWithConsoleOutput));
        }

This will print something like this

(root): not equal - x: UsageOfNugetPackage.UseWithNUnit+SomeObject y: UsageOfNugetPackage.UseWithNUnit+SomeObject
  Text: not equal - x: abcd y: abc
  Number: equal - x: 12 y: 12

Write comparison result to a TextWriter

     var textWriter = new StringWriter();

     var comparer = DeepEqualityComparer
        .CreateConfiguration()
        .SetLoggingTextWriter(textWriter)
        .CreateEqualityComparer();

      Assert.That(so1, Is.EqualTo(so2).Using(comparer));

Ignore Properties by name

    var so1 = new SomeObject { Number = 12, Text = "abc" };
    var so2 = new SomeObject { Number = 12, Text = "abcd" };

    var comparer = DeepEqualityComparer
        .CreateConfiguration()
        .IgnorePropertyByName("Text")
        .CreateEqualityComparer();

        Assert.That(so1, Is.EqualTo(so2).Using(comparer));

Configure how strings are compared

Configure StringComparison

    var text1 = "abcd";
    var text2 = "ABCD";

    var comparer =
        DeepEqualityComparer.CreateConfiguration()
            .ConfigureStringComparison(StringComparison.OrdinalIgnoreCase)
            .CreateEqualityComparer();

    Assert.That(text1, Is.EqualTo(text2).Using(comparer));

Treat Null As Empty String

    var so1 = new SomeObject { Number = 12, Text = string.Empty };
    var so2 = new SomeObject { Number = 12, Text = null };

    var comparer = 
        DeepEqualityComparer.CreateConfiguration()
            .TreatNullAsEmptyString(true)
            .CreateEqualityComparer();

    Assert.That(so1, Is.EqualTo(so2).Using(comparer));