Ensure new Lti::ToolProxies on root account can find others

fixes: INTEROP-6245
flag=none

Test plan
- Create 2 lti tool proxies for the same plagiarism family
  on the root account and ensure they don't create 2
  separate live event subscriptions

Change-Id: I86a28011c47c3ee8c680359c5576afc0ec5e8137
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/249556
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Weston Dransfield <wdransfield@instructure.com>
QA-Review: Weston Dransfield <wdransfield@instructure.com>
Product-Review: Mysti Lilla <mysti@instructure.com>

app/models/lti/tool_proxy.rb

@@ -171,7 +171,8 @@ module Lti
       # Search the accounts under the same root account to see if a subscription already exists
       # (we only need one subscription per root account)
       subscription_id = tool_proxies.joins(:account).
-        find_by("coalesce(accounts.root_account_id, accounts.id) = ?", context&.root_account_id)&.subscription_id
+        # we should replace this with the tool_proxy root_account_id if/when we fill that
+        find_by("coalesce(accounts.root_account_id, accounts.id) = ?", context&.resolved_root_account_id)&.subscription_id
       # Then search courses in case the tool was only directly installed on a course
       subscription_id ||= tool_proxies.joins(:course).
         find_by(courses: {root_account_id: self.context&.root_account_id})&.subscription_id

spec/models/lti/tool_proxy_spec.rb

@@ -638,6 +638,26 @@ module Lti
         expect(tool_proxy.subscription_id).to eq 'id'
       end
 
+      it 'should not create a subscription if a root account tool already has one' do
+        ToolProxy.create!(
+          raw_data: {'enabled_capability' => [placement]},
+          subscription_id: 'id',
+          context: account,
+          shared_secret: 'shared_secret',
+          guid: 'guid',
+          product_version: '1.0beta',
+          lti_version: 'LTI-2p0',
+          product_family: product_family,
+          workflow_state: 'active'
+        )
+
+        expect_any_instance_of(Lti::PlagiarismSubscriptionsHelper).not_to receive(:create_subscription)
+        tool_proxy.context = account
+        tool_proxy.raw_data['enabled_capability'] = [placement]
+        tool_proxy.save!
+        expect(tool_proxy.subscription_id).to eq 'id'
+      end
+
       it 'should not create subscriptions for non-plagiarism tools' do
         expect_any_instance_of(Lti::PlagiarismSubscriptionsHelper).not_to receive(:create_subscription)
         tool_proxy.raw_data['enabled_capability'] = []