Worldpay: Format non-fractional currency amounts correctly

#2084 introduced a
regression to the Worldpay gateway wherein it was no longer implementing
the correct contract for non-fractional currencies.

Our [base gateway
tests](https://github.com/jasonwebster/active_merchant/blob/07e28c4936c2ae46f0470d878c19f36564c3df6e/test/unit/gateways/gateway_test.rb#L83-L91)
and [Stripe
tests](https://github.com/jasonwebster/active_merchant/blob/07e28c4936c2ae46f0470d878c19f36564c3df6e/test/unit/gateways/stripe_test.rb#L431-L440)
for example, which is another gateway with a `:cents` money format,
ensure that you want to charge ¥100, you actually have to pass in
`10000`, as if the non-fractional currency _was_ fractional. That's the
external contract of Active Merchant--all transaction amounts accepted
by the public API methods are expected to be in cents, period.

Closes #2267

CHANGELOG

@@ -20,6 +20,7 @@
 * Authorize.net: Add line item fields and additional transaction settings [shasum]
 * Authorize.net: Pass through `header_email_receipt` [shasum]
 * Stripe: Scrub additional network tokenization related sensitive data [jasonwebster] #2251
+* Applying: Worldpay: Format non-fractional currency amounts correctly [jasonwebster] #2267
 
 == Version 1.61.0 (November 7, 2016)
 * Add codes AQ, BQ, SX, and SS to list of countries and update SD numeric code [zxlin]

lib/active_merchant/billing/gateways/worldpay.rb

@@ -187,7 +187,7 @@ def add_amount(xml, money, options)
         currency = options[:currency] || currency(money)
 
         amount_hash = {
-          :value => amount(money),
+          :value => localized_amount(money, currency),
           'currencyCode' => currency,
           'exponent' => non_fractional_currency?(currency) ? 0 : 2
         }

test/unit/gateways/worldpay_test.rb

@@ -190,9 +190,20 @@ def test_amount_handling
     end.respond_with(successful_authorize_response)
   end
 
+  def test_non_fractional_amount_handling_with_moneylike
+    amount = OpenStruct.new(cents: 10000)
+    stub_comms do
+      @gateway.authorize(amount, @credit_card, @options.merge(currency: 'JPY'))
+    end.check_request do |endpoint, data, headers|
+      assert_tag_with_attributes 'amount',
+          {'value' => '100', 'exponent' => '0', 'currencyCode' => 'JPY'},
+        data
+    end.respond_with(successful_authorize_response)
+  end
+
   def test_currency_exponent_handling
     stub_comms do
-      @gateway.authorize(100, @credit_card, @options.merge(currency: :JPY))
+      @gateway.authorize(10000, @credit_card, @options.merge(currency: :JPY))
     end.check_request do |endpoint, data, headers|
       assert_tag_with_attributes 'amount',
           {'value' => '100', 'exponent' => '0', 'currencyCode' => 'JPY'},