Expand EP400 Merge eligibility to multi-contention claims (#17440)

* Expand EP400 Merge eligibility to multi-contention claims

* Fix lint warning

app/models/concerns/form526_claim_fast_tracking_concern.rb

@@ -121,9 +121,11 @@ def diagnostic_codes
   end
 
   def eligible_for_ep_merge?
+    user = User.find(user_uuid)
+    return true if Flipper.enabled?(:disability_526_ep_merge_multi_contention, user)
     return false unless disabilities.count == 1
 
-    Flipper.enabled?(:disability_526_ep_merge_new_claims, User.find(user_uuid)) ? increase_or_new? : increase_only?
+    Flipper.enabled?(:disability_526_ep_merge_new_claims, user) ? increase_or_new? : increase_only?
   end
 
   def prepare_for_evss!

config/features.yml

@@ -388,6 +388,9 @@ features:
   disability_526_ep_merge_new_claims:
     actor_type: user
     description: enables EP Merge for single-contention 526 claims for a new condition
+  disability_526_ep_merge_multi_contention:
+    actor_type: user
+    description: enables EP Merge for multi-contention 526 claims
   disability_526_toxic_exposure:
     actor_type: user
     description: enables new pages, processing, and submission of toxic exposure claims

spec/models/form526_submission_spec.rb

@@ -1274,10 +1274,20 @@ def expect_max_cfi_logged(max_cfi_enabled, disability_claimed, diagnostic_code,
   describe '#eligible_for_ep_merge?' do
     subject { Form526Submission.create(form_json: File.read(path)).eligible_for_ep_merge? }
 
+    before { Flipper.disable(:disability_526_ep_merge_multi_contention) }
+
     context 'when there are multiple contentions' do
       let(:path) { 'spec/support/disability_compensation_form/submissions/only_526_mixed_action_disabilities.json' }
 
-      it { is_expected.to be_falsey }
+      context 'when multi-contention claims are not eligible' do
+        it { is_expected.to be_falsey }
+      end
+
+      context 'when multi-contention claims are eligible' do
+        before { Flipper.enable(:disability_526_ep_merge_multi_contention) }
+
+        it { is_expected.to be_truthy }
+      end
     end
 
     context 'when there is a single new contention' do