gistfile1.rb

>> ActiveMerchant::Billing.constants
=> ["AuthorizedNetGateway", "PayflowGateway", "Integrations", 
    "PaypalExpressGateway", "BrainTreeGateway", "UsaEpayGateway", 
    "AVSResult", "PayflowUkGateway", "DataCashGateway", "BeanstreamCore", 
    "Error", "EfsnetGateway", "PaypalGateway", "ModernPaymentsGateway", 
    "SageCore", "PaypalCaGateway", "SecurePayAuGateway", 
    "AuthorizeNetGateway", "SkipJackGateway", "CardStreamGateway", 
    "SageGateway", "Gateway", "TrustCommerceGateway", "PaypalExpressCommon", 
    "SecurePayTechGateway", "PayflowExpressResponse", "AuthorizeNetCimGateway", 
    "CVVResult", "CreditCardFormatting", "PayflowCommonAPI", 
    "BeanstreamInteracResponse", "Base", "QuickpayGateway", 
    "PaypalExpressResponse", "EwayGateway", "ViaklixGateway", "BogusGateway", 
    "Check", "PaymentExpressResponse", "RealexGateway", "VerifiGateway", 
    "Response", "PayflowExpressGateway", "ProtxGateway", "PaymentExpressGateway", 
    "PayJunctionGateway", "PaypalCommonAPI", "CreditCard", "PayflowResponse", 
    "NetRegistryGateway", "ModernPaymentsCimGateway", "PlugnpayGateway", 
    "CyberSourceGateway", "TransFirstGateway", "NetbillingGateway", 
    "PayflowExpressUkGateway", "SageBankcardGateway", "MonerisGateway", 
    "PslCardGateway", "BeanstreamGateway", "LinkpointGateway", 
    "CreditCardMethods", "SageVirtualCheckGateway", "PsigateGateway", 
    "BeanstreamInteracGateway", "ExactGateway", "WirecardGateway", 
    "BraintreeGateway", "SecurePayGateway", "PaySecureGateway"]
>> ActiveMerchant::Billing::Integrations.constants
=> ["Notification", "Helper", "Return", "Gestpay", "HiTrust", 
    "Paypal", "Nochex", "Chronopay", "Quickpay", "Bogus", "TwoCheckout"]