First two fail (as expected), but with an unexpected error message, e.g., "For Customer, expected <>f__AnonymousType3`1[System.String]:[{ Name = Expected Name }] but found ExpectedObjectsAssertions.Customer."

ExpectedObjects_ShouldEqual_vs_ShouldMatch_with_partial_objects.cs

[TestFixture]
public class When_testing_equivalence_or_matching_for_partially_supplied_properties
{
	private const string ExpectedName = "Expected Name";
	private Customer _actual;
	private ExpectedObject _expected;

	[Test]
	public void Should_flag_extra_properties_on_actual_object_as_unequal()
	{
		_actual = new Customer {Name = ExpectedName, PhoneNumber = "1234567890"};
		_expected = new {Name = ExpectedName}.ToExpectedObject();
		_expected.ShouldEqual(_actual);
	}

	[Test]
	public void Should_flag_uninitialized_properties_on_actual_object_as_unequal()
	{
		_actual = new Customer {Name = ExpectedName};
		_expected = new {Name = ExpectedName, PhoneNumber = "1234567890"}.ToExpectedObject();
		_expected.ShouldEqual(_actual);
	}

	[Test]
	public void Should_flag_uninitialized_properties_on_actual_object_as_not_matching()
	{
		_actual = new Customer {Name = ExpectedName};
		_expected = new {Name = ExpectedName, PhoneNumber = "1234567890"}.ToExpectedObject();
		_expected.ShouldMatch(_actual); //fails as expected
	}

	[Test]
	public void Should_ignore_extra_properties_on_actual_object_when_matching()
	{
		_actual = new Customer {Name = ExpectedName, PhoneNumber = "1234567890"};
		_expected = new {Name = ExpectedName}.ToExpectedObject();
		_expected.ShouldMatch(_actual); //passes as expected
	}
}