Is it possible to make 3D Secure payments through a Braintree sandbox environment with C#?

Question

I have written code in .NET Standard 2.0 to make payments through Braintree. The code uses the Braintree 5.2.0 NuGet package. I intend to exclusively make 3D Secure payments when the code is used against a Braintree production account. I have written a integration test that creates a customer, creates a payment method for that customer, then makes a payment against that payment method using the Token that was generated.

The code to create a customer is:

public async Task<string> SeedCustomer(IBraintreeConfiguration braintreeConfiguration)
{
    BraintreeGateway _braintreeGateway = new BraintreeGateway(
        braintreeConfiguration.Environment,
        braintreeConfiguration.MerchantId,
        braintreeConfiguration.PublicKey,
        braintreeConfiguration.PrivateKey
    );

    CustomerRequest request = new CustomerRequest
    {
        Email = BraintreeTestConstants.Email,
        CustomFields = new Dictionary<string, string>
        {
            {"account_id", BraintreeTestConstants.AccountId}
        }
    };

    string braintreeCustomerId = 
        (await _braintreeGateway.Customer.CreateAsync(request)).Target.Id;

    return braintreeCustomerId;
}

The code to create a payment method is:

PaymentMethodRequest paymentMethodRequest = new PaymentMethodRequest
{
    PaymentMethodNonce = nonce,
    CustomerId = customerId,
    BillingAddress = new PaymentMethodAddressRequest
    {
        FirstName = BraintreeTestConstants.BillingName,
        Locality = BraintreeTestConstants.City,
        Company = BraintreeTestConstants.CompanyName,
        CountryCodeAlpha2 = BraintreeTestConstants.Country,
        ExtendedAddress = BraintreeTestConstants.ExtendedAddress,
        Region = BraintreeTestConstants.State,
        StreetAddress = BraintreeTestConstants.StreetAddress,
        PostalCode = BraintreeTestConstants.Zip,
    },
    Options = new PaymentMethodOptionsRequest
    {
        VerifyCard = true
    }
};

Result<PaymentMethod> result = 
    await _braintreeGateway.PaymentMethod.CreateAsync(paymentMethodRequest);

return _mapper.Map<AddPaymentMethodResultModel>((CreditCard)result.Target);

CreditCard.Token is mapped to AddPaymentMethodResultModel.CardId.

The code to make a payment is:

bool useThreeDSecure = true;

TransactionRequest transactionRequest = new TransactionRequest
{
    Amount = Amount,
    PaymentMethodToken = CardId,
    MerchantAccountId = string.IsNullOrWhiteSpace(MerchantAccountId) ? null : MerchantAccountId,
    TransactionSource = string.IsNullOrWhiteSpace(TransactionSource) ? null : TransactionSource,
    Options = new TransactionOptionsRequest
    {
        SubmitForSettlement = true,
        ThreeDSecure = new TransactionOptionsThreeDSecureRequest
        {
            Required = useThreeDSecure
        }
    }
};

if (Address != null)
{
    transactionRequest.BillingAddress = new AddressRequest
    {
        Company = Address.CompanyName,
        FirstName = Address.BillingName,
        StreetAddress = Address.StreetAddress,
        ExtendedAddress = Address.ExtendedAddress,
        Locality = Address.City,
        Region = Address.State,
        PostalCode = Address.Zip,
        CountryCodeAlpha2 = Address.Country
    };
}

Result<Transaction> result =
    await _braintreeGateway.Transaction.SaleAsync(transactionRequest);

When I execute the test against a Braintree sandbox environment with TransactionRequest.Options.ThreeDSecure.Required set to false, a payment is successful.

When I execute the test against a Braintree sandbox environment TransactionRequest.Options.ThreeDSecure.Required set to true, a payment fails with a Result.Message of Gateway Rejected: three_d_secure.

I was wondering whether it is possible to make a successful payment through a Braintree sandbox environment with TransactionRequest.Options.ThreeDSecure.Required set to true. I have tried unsuccessfully using a payment method created through the NuGet package with a PaymentMethodNonce of fake-three-d-secure-visa-full-authentication-nonce. I have also tried unsuccessfully using a payment method created through the Braintree sandbox dashboard using details of a test Visa card from https://support.bluesnap.com/docs/test-credit-card-numbers.

I would like to prove that a 3D Secure payment can be made through a Braintree sandbox environment to have confidence that the code will work against a Braintree production environment.