Add ability to delete all subscriptions by tool_proxy

fixes PLAT-2460

This will need to be tested in conjunction with a commit in the
live-events-subscription project

Test plan:
* Start the subscription service
* With the canvas api or in a rails console create a bunch of
  subscriptions using the same tool proxy
* Using the rails console issue the following command passing in the
  tool proxy
  res = Services::LiveEventsSubscriptionService.destroy_all_tool_proxy_subscriptions(tp)
* Ensure that canvas makes the right request to the subscription service
  and that the subscription service returns a 200

Change-Id: Ied5527d46db50bec14de0455907b209cb1375df2
Reviewed-on: https://gerrit.instructure.com/108834
Tested-by: Jenkins
Reviewed-by: Matthew Wheeler <mwheeler@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Andrew Butterfield <abutterfield@instructure.com>

lib/services/live_events_subscription_service.rb

@@ -36,6 +36,11 @@ module Services
         request(:delete, "/api/subscriptions/#{subscription_id}", options)
       end
 
+      def destroy_all_tool_proxy_subscriptions(tool_proxy)
+        options = { headers: headers(tool_proxy_jwt_body(tool_proxy)) }
+        request(:delete, "/api/subscriptions", options)
+      end
+
       private
       def request(method, endpoint, options = {})
         Canvas.timeout_protection("live-events-subscription-service-session", raise_on_timeout: true) do

spec/lib/services/live_events_subscription_service_spec.rb

@@ -81,6 +81,21 @@ module Services
         end
       end
 
+      describe '.destroy_all_tool_proxy_subscriptions' do
+        it 'makes the expected request' do
+          tool_proxy.stubs(:context).returns(root_account_context)
+          HTTParty.expects(:send).with do |method, endpoint, options|
+            expect(method).to eq(:delete)
+            expect(endpoint).to eq('http://example.com/api/subscriptions')
+            jwt = Canvas::Security::ServicesJwt.new(options[:headers]['Authorization'].gsub('Bearer ',''), false).original_token
+            expect(jwt["DeveloperKey"]).to eq('10000000000003')
+            expect(jwt["RootAccountId"]).to eq('10000000000004')
+            expect(jwt["sub"]).to eq('ltiToolProxy:151b52cd-d670-49fb-bf65-6a327e3aaca0')
+          end
+          LiveEventsSubscriptionService.destroy_all_tool_proxy_subscriptions(tool_proxy)
+        end
+      end
+
       describe '.destroy_tool_proxy_subscription' do
         it 'makes the expected request' do
           tool_proxy.stubs(:context).returns(root_account_context)