spec: Add list of external pact consumers

Add list of external pact consumers to use when pulling from
external pact broker. The pact.verify rake task fails deep
inside pact code if it can't find a pact file it's expecting.

Change-Id: I61f17d83812a4f5658887b7cf3c0d85fd66d4ae1
Reviewed-on: https://gerrit.instructure.com/158976
Tested-by: Jenkins
Reviewed-by: Anju Reddy <areddy@instructure.com>
Product-Review: Robert Lamb <rlamb@instructure.com>
QA-Review: Robert Lamb <rlamb@instructure.com>

spec/contracts/service_consumers/pact_config.rb

@@ -17,6 +17,7 @@
 #
 
 module PactConfig
+  EXTERNAL_BROKER_HOST = 'pact-broker.instructure.com'.freeze
   # These constants ensure we use the correct strings and thus help avoid our
   # accidentally breaking the contract tests
   module Providers
@@ -29,8 +30,15 @@ module PactConfig
 
   # Add new API and LiveEvents consumers to this Consumers module
   module Consumers
-    GENERIC_CONSUMER = 'Generic Consumer'.freeze
-    QUIZ_LTI = 'Quiz LTI'.freeze
+    my_broker_host = ENV.fetch('PACT_BROKER_HOST', 'pact-broker.docker')
+    if my_broker_host.include?(EXTERNAL_BROKER_HOST)
+      # extrnal consumers
+      GENERIC_CONSUMER = 'Generic Consumer'.freeze
+    else
+      # internal consumers
+      GENERIC_CONSUMER = 'Generic Consumer'.freeze
+      QUIZ_LTI = 'Quiz LTI'.freeze
+    end
     ALL = Consumers.constants.map { |c| Consumers.const_get(c) }.freeze
   end