Shopify/active_merchant — pull request #489 by moklett (2012-10-27 15:33:51+00:00)
Title: PaymentExpress: Limit MerchantReference/description to 64 chars

PaymentExpress enforces a max length on the MerchantReference field of 64 characters. This field is derived from the description field which is passed in the options hash.

Before, MerchantReference was unbounded. If more than 64 characters were passed in this field, PaymentExpress would return an error when running the transaction.

Documentation: http://www.paymentexpress.com/technical_resources/ecommerce_nonhosted/pxpost.html#MerchantReference

Note: This commit also includes a test verifying that TxnId is limited to 16 characters. This restriction was already implemented, but untested.

Documentation: http://www.paymentexpress.com/technical_resources/ecommerce_nonhosted/pxpost.html#TxnId