Change NRPS service_version sub-claim to service_versions

- Per recent NRPS vs spec change, the `service_version` LTI 1.3
  launch sub-claim is renamed to `service_versions` and its type
  changed from a string to an array of strings. (The expressed
  version itself is still the same, i.e. it just appears as
  ["2.0"] instead of an unwrapped "2.0".)

Closes LTIA-35 WIP

Test Plan:

  - Verify LTI 1.3 launches to the IMS Reference Implementation include
  a https://purl.imsglobal.org/spec/lti-nrps/claim/namesroleservice
  claim with a `"service_versions": ["2.0"]` sub-claim

Change-Id: I53801d633166a07c571e106cc60256729059fdcf
Reviewed-on: https://gerrit.instructure.com/167714
QA-Review: Samuel Barney <sbarney@instructure.com>
Tested-by: Jenkins
Product-Review: Karl Lloyd <karl@instructure.com>
Reviewed-by: Marc Phillips <mphillips@instructure.com>

gems/lti-advantage/lib/lti_advantage/claims/names_and_roles_service.rb

@@ -7,8 +7,8 @@ module LtiAdvantage::Claims
     include ActiveModel::Model
 
     attr_accessor :context_memberships_url,
-                  :service_version
+                  :service_versions
 
-    validates_presence_of :context_memberships_url, :service_version
+    validates_presence_of :context_memberships_url, :service_versions
   end
 end

lib/lti/messages/jwt_message.rb

@@ -137,7 +137,7 @@ module Lti::Messages
     def add_names_and_roles_service_claims!
       @message.names_and_roles_service.context_memberships_url =
         @expander.controller.polymorphic_url([@context, :names_and_roles])
-      @message.names_and_roles_service.service_version = '2.0'
+      @message.names_and_roles_service.service_versions = ['2.0']
     end
 
     def expand_variable(variable)

spec/lib/lti/messages/jwt_message_spec.rb

@@ -248,6 +248,16 @@ describe Lti::Messages::JwtMessage do
       end
     end
 
+    shared_examples 'names and roles claim check' do
+      it 'sets the NRPS url' do
+        expect(message_names_and_roles_service['context_memberships_url']).to eq 'polymorphic_url'
+      end
+
+      it 'sets the NRPS version' do
+        expect(message_names_and_roles_service['service_versions']).to eq ['2.0']
+      end
+    end
+
     describe 'names and roles' do
       let(:message_names_and_roles_service) { decoded_jwt['https://purl.imsglobal.org/spec/lti-nrps/claim/namesroleservice'] }
 
@@ -285,12 +295,8 @@ describe Lti::Messages::JwtMessage do
         course.root_account.save!
       end
 
-      it 'sets the NRPS url' do
-        expect(message_names_and_roles_service['context_memberships_url']).to eq 'polymorphic_url'
-      end
-
-      it 'sets the NRPS version' do
-        expect(message_names_and_roles_service['service_version']).to eq '2.0'
+      context 'when context is a course' do
+        it_behaves_like 'names and roles claim check'
       end
 
       context 'when context is an account' do
@@ -330,13 +336,7 @@ describe Lti::Messages::JwtMessage do
           )
         end
 
-        it 'sets the NRPS url' do
-          expect(message_names_and_roles_service['context_memberships_url']).to eq 'polymorphic_url'
-        end
-
-        it 'sets the NRPS version' do
-          expect(message_names_and_roles_service['service_version']).to eq '2.0'
-        end
+        it_behaves_like 'names and roles claim check'
       end
     end
   end