/// <summary>
        /// Tests if the provider invalidates a user using the given password format.
        /// </summary>
        /// <param name="passwordFormat"></param>
        private void TestValidateUserWithWrongPasswordWithPasswordFormat(string passwordFormat)
        {
            var config = new NameValueCollection(_config);
            config["passwordFormat"] = passwordFormat;

            var provider = new MongoMembershipProvider();
            provider.Initialize(DefaultName, config);

            MembershipCreateStatus status;
            provider.CreateUser("test", "123456", "*****@*****.**", null, null, true, null, out status);

            var validated = provider.ValidateUser("test", "XXXXXX");
            Assert.IsFalse(validated);
        }