Implement review comments from @DouweM.

app/models/concerns/protected_branch_access.rb

@@ -2,8 +2,8 @@ module ProtectedBranchAccess
   extend ActiveSupport::Concern
 
   included do
-    scope :master, -> () { where(access_level: Gitlab::Access::MASTER) }
-    scope :developer, -> () { where(access_level: Gitlab::Access::DEVELOPER) }
+    scope :master, -> { where(access_level: Gitlab::Access::MASTER) }
+    scope :developer, -> { where(access_level: Gitlab::Access::DEVELOPER) }
   end
 
   def humanize

app/services/protected_branches/api_create_service.rb

@@ -11,18 +11,23 @@ module ProtectedBranches
     end
 
     def execute
+      push_access_level =
         if @developers_can_push
-        @params.merge!(push_access_levels_attributes: [{ access_level: Gitlab::Access::DEVELOPER }])
+          Gitlab::Access::DEVELOPER
         else
-        @params.merge!(push_access_levels_attributes: [{ access_level: Gitlab::Access::MASTER }])
+          Gitlab::Access::MASTER
         end
 
+      merge_access_level =
         if @developers_can_merge
-        @params.merge!(merge_access_levels_attributes: [{ access_level: Gitlab::Access::DEVELOPER }])
+          Gitlab::Access::DEVELOPER
         else
-        @params.merge!(merge_access_levels_attributes: [{ access_level: Gitlab::Access::MASTER }])
+          Gitlab::Access::MASTER
         end
 
+      @params.merge!(push_access_levels_attributes: [{ access_level: push_access_level }],
+                     merge_access_levels_attributes: [{ access_level: merge_access_level }])
+
       service = ProtectedBranches::CreateService.new(@project, @current_user, @params)
       service.execute
     end

lib/api/branches.rb

@@ -57,11 +57,11 @@ module API
         developers_can_merge = to_boolean(params[:developers_can_merge])
         developers_can_push = to_boolean(params[:developers_can_push])
 
-        params = {
+        protected_branch_params = {
           name: @branch.name,
         }
 
-        service_args = [user_project, current_user, params,
+        service_args = [user_project, current_user, protected_branch_params,
                         developers_can_push: developers_can_push,
                         developers_can_merge: developers_can_merge]