feat: Conversation update API for sla_policy_id (#8973)

- Add an endpoint for updating conversation attributes (priority / sla_policy_id )
- Swagger spec
- minor chores around the conversation API/spec

Fixes: https://linear.app/chatwoot/issue/CW-2100/feat-backend-api-to-update-the-sla-of-a-conversation

spec/enterprise/models/conversation_spec.rb

@@ -7,10 +7,10 @@ RSpec.describe Conversation, type: :model do
 
   describe 'SLA policy updates' do
     let!(:conversation) { create(:conversation) }
-    let!(:sla_policy) { create(:sla_policy) }
+    let!(:sla_policy) { create(:sla_policy, account: conversation.account) }
 
     it 'generates an activity message when the SLA policy is updated' do
-      conversation.update(sla_policy_id: sla_policy.id)
+      conversation.update!(sla_policy_id: sla_policy.id)
 
       perform_enqueued_jobs
 
@@ -21,18 +21,19 @@ RSpec.describe Conversation, type: :model do
       expect(activity_message.content).to include('added SLA policy')
     end
 
-    it 'generates an activity message when the SLA policy is removed' do
-      conversation.update(sla_policy_id: sla_policy.id)
-      conversation.update(sla_policy_id: nil)
+    # TODO: Reenable this when we let the SLA policy be removed from a conversation
+    # it 'generates an activity message when the SLA policy is removed' do
+    #   conversation.update!(sla_policy_id: sla_policy.id)
+    #   conversation.update!(sla_policy_id: nil)
 
-      perform_enqueued_jobs
+    #   perform_enqueued_jobs
 
-      activity_message = conversation.messages.where(message_type: 'activity').last
+    #   activity_message = conversation.messages.where(message_type: 'activity').last
 
-      expect(activity_message).not_to be_nil
-      expect(activity_message.message_type).to eq('activity')
-      expect(activity_message.content).to include('removed SLA policy')
-    end
+    #   expect(activity_message).not_to be_nil
+    #   expect(activity_message.message_type).to eq('activity')
+    #   expect(activity_message.content).to include('removed SLA policy')
+    # end
   end
 
   describe 'conversation sentiments' do
@@ -64,4 +65,43 @@ RSpec.describe Conversation, type: :model do
       expect(sentiments[:label]).to eq('positive')
     end
   end
+
+  describe 'sla_policy' do
+    let(:account) { create(:account) }
+    let(:conversation) { create(:conversation, account: account) }
+    let(:sla_policy) { create(:sla_policy, account: account) }
+    let(:different_account_sla_policy) { create(:sla_policy) }
+
+    context 'when sla_policy is getting updated' do
+      it 'throws error if sla policy belongs to different account' do
+        conversation.sla_policy = different_account_sla_policy
+        expect(conversation.valid?).to be false
+        expect(conversation.errors[:sla_policy]).to include('sla policy account mismatch')
+      end
+
+      it 'creates applied sla record if sla policy is present' do
+        conversation.sla_policy = sla_policy
+        conversation.save!
+        expect(conversation.applied_sla.sla_policy_id).to eq(sla_policy.id)
+      end
+    end
+
+    context 'when conversation already has a different sla' do
+      before do
+        conversation.update(sla_policy: create(:sla_policy, account: account))
+      end
+
+      it 'throws error if trying to assing a different sla' do
+        conversation.sla_policy = sla_policy
+        expect(conversation.valid?).to be false
+        expect(conversation.errors[:sla_policy]).to eq(['conversation already has a different sla'])
+      end
+
+      it 'throws error if trying to set sla to nil' do
+        conversation.sla_policy = nil
+        expect(conversation.valid?).to be false
+        expect(conversation.errors[:sla_policy]).to eq(['cannot remove sla policy from conversation'])
+      end
+    end
+  end
 end