private IUsersConfig CreateUserConfig(string xml) {
			var config = CreateConfig(xml);
			var factory = new UsersConfigFactory();
			return factory.Create(config);
		}
		public void Create_PassNullConfig_ThrowsArgumentNullException() {
			var factory = new UsersConfigFactory();
			Assert.Throws<ArgumentNullException>(() => factory.Create(null));
		}