add spec for launching lti2 tools in new tabs

fixes PLAT-779

test-plan:
the spec should pass

Change-Id: I47ae1677bc65b96968a07123215ab20d5fa94186
Reviewed-on: https://gerrit.instructure.com/46959
Reviewed-by: Brad Humphrey <brad@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Nathan Mills <nathanm@instructure.com>
QA-Review: Nathan Mills <nathanm@instructure.com>

spec/controllers/lti/message_controller_spec.rb

@@ -162,6 +162,15 @@ module Lti
           expect(params['custom_canvas.module_item.id']).to eq tag.id
         end
 
+        it 'sets the launch to window' do
+          tag = message_handler.context_module_tags.create!(context: account, tag_type: 'context_module', new_tab: true)
+          tag.context_module =  ContextModule.create!(context: Course.create!)
+          tag.save!
+          get 'basic_lti_launch_request', account_id: account.id, message_handler_id: message_handler.id, module_item_id: tag.id, params: {tool_launch_context: 'my_custom_context' }
+          expect(response.code).to eq "200"
+          expect(assigns[:lti_launch].launch_type).to eq 'window'
+        end
+
         it 'returns the locale' do
           get 'basic_lti_launch_request', account_id: account.id, message_handler_id: message_handler.id, params: {tool_launch_context: 'my_custom_context'}
           params = assigns[:lti_launch].params.with_indifferent_access