.NET Object extension methods to shortcut null argument checks.

ObjectExtensions.cs

using System;

namespace Extensions
{
    /// <summary>
    /// Contains <see cref="object"/> extension methods.
    /// </summary>
    public static class ObjectExtensions
    {
        /// <summary>
        /// Checks for and throws an <see cref="ArgumentNullException"/> if the object is null.
        /// </summary>
        /// <param name="param">The <see cref="object"/>.</param>
        /// <exception cref="ArgumentNullException"><b>parm</b> was null.</exception>
        public static void CheckNull(this object param)
        {
            param.CheckNull(null);
        }

        /// <summary>
        /// Checks for and throws an <see cref="ArgumentNullException"/> if the object is null.
        /// </summary>
        /// <param name="param">The <see cref="object"/>.</param>
        /// <param name="parmName">Name of the parameter to check.</param>
        /// <exception cref="ArgumentNullException"><b>param</b> was null.</exception>
        public static void CheckNull(this object param, string parmName)
        {
            if (param == null)
            {
                throw new ArgumentNullException(parmName);
            }
        }
    }
}

ObjectExtensionsFixture.cs

using System;
using Extensions;
using NUnit.Framework;

namespace tests.Extensions
{
    [TestFixture]
    public class ObjectExtensionsFixture
    {
        [Test]
        public void TestIsParameterNull()
        {
            new object().CheckNull();

            object o = null;
            Assert.Throws<ArgumentNullException>(() => o.CheckNull());
        }

        [Test]
        public void TestIsParameterNullWithNull()
        {
            object obj = null;
            Assert.That(() => obj.CheckNull(), Throws.TypeOf<ArgumentNullException>().With.Message.EqualTo("Value cannot be null."));
        }

        [Test]
        public void TestIsParameterNullWithName()
        {
            new object().CheckNull("parameter1");
        }

        [Test]
        public void TestIsParameterNullWithNullAndName()
        {
            object obj = null;
            Assert.That(() => obj.CheckNull("parameter1"), Throws.TypeOf<ArgumentNullException>().With.Message.EqualTo("Value cannot be null.\r\nParameter name: parameter1"));
        }
    }
}