gistfile1.cs

using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Xunit;

public class When_overriding_GetHashCode
{
    [Fact]
    public void Equals_should_be_overridden()
    {
        var dlls = new List<Assembly>
            {
                Assembly.Load("some.assembly"),
                Assembly.Load("another.assembly"),
            };

        var missing = from assembly in dlls
                      from type in assembly.GetTypes()
                      let methods = type.GetMethods()
                      where methods.Any(x => x.Name == "GetHashCode" && x.DeclaringType == type)
                            && !methods.Any(x => x.Name == "Equals" && x.DeclaringType == type)
                      select new {Type = type, Assembly = assembly};

        var messages = from item in missing
                       select
                           string.Format(
                           "The type {0} overrides GetHashCode() but not override Equals(), in assembly {1}.",
                           item.Type.Name,
                           item.Assembly.GetName());

        Assert.True(missing.Count() == 0, string.Join("\n", messages.ToArray()));
    }
}