fix bug in pluralization of “branches” in slack message body

Author: yasunariw

lib/slack.ml

@@ -292,12 +292,16 @@ let generate_status_notification (cfg : Config_t.config) (notification : status_
   let branches_info =
     match List.map ~f:(fun { name } -> name) notification.branches with
     | [] -> [] (* happens when branch is force-pushed by the time CI notification arrives *)
-    | branches ->
-    match cfg.main_branch_name with
-    | Some main when List.mem branches main ~equal:String.equal ->
-      (* happens when new branches are branched before CI finishes *)
-      [ sprintf "*Branch*: %s" main ]
-    | _ -> [ sprintf "*Branches*: %s" (String.concat ~sep:", " branches) ]
+    | notification_branches ->
+      let branches =
+        match cfg.main_branch_name with
+        | Some main when List.mem notification_branches main ~equal:String.equal ->
+          (* happens when new branches are branched before CI finishes *)
+          [ main ]
+        | _ -> notification_branches
+      in
+      let pluralize s = if Int.equal (List.length branches) 1 then s else sprintf "%ses" s in
+      [ sprintf "*%s*: %s" (pluralize "Branch") (String.concat ~sep:", " branches) ]
   in
   let summary =
     match target_url with

test/slack_payloads.expected

@@ -477,7 +477,7 @@ will notify #default
       "fields": [
         {
           "value":
-            "*Commit*: `<https://github.com/ahrefs/monorepo/commit/0d95302addd66c1816bce1b1d495ed1c93ccd478|0d95302a>` Update README.md - Khady\n*Branches*: master"
+            "*Commit*: `<https://github.com/ahrefs/monorepo/commit/0d95302addd66c1816bce1b1d495ed1c93ccd478|0d95302a>` Update README.md - Khady\n*Branch*: master"
         }
       ]
     }
@@ -543,7 +543,7 @@ will notify #default
       "fields": [
         {
           "value":
-            "*Commit*: `<https://github.com/ahrefs/monorepo/commit/0d95302addd66c1816bce1b1d495ed1c93ccd478|0d95302a>` Update README.md - Khady\n*Branches*: master"
+            "*Commit*: `<https://github.com/ahrefs/monorepo/commit/0d95302addd66c1816bce1b1d495ed1c93ccd478|0d95302a>` Update README.md - Khady\n*Branch*: master"
         }
       ]
     }