public void when_ContainsKey_that_does_not_exist_then_returns_false()
		{
			var dictionary = new NotNullDictionary<String, String>();

			var result = dictionary.ContainsKey("foo");

			Assert.IsFalse(result);
		}
		public void when_ContainsKey_that_exists_then_returns_true()
		{
			var dictionary = new NotNullDictionary<String, String>();
			dictionary.Add("foo", "bar");

			var result = dictionary.ContainsKey("foo");

			Assert.IsTrue(result);
		}