fix to allow integer label refernces

app/assets/javascripts/gfm_auto_complete.js

@@ -338,7 +338,8 @@ class GfmAutoComplete {
         let resultantValue = value;
         if (value && !this.setting.skipSpecialCharacterTest) {
           const withoutAt = value.substring(1);
-          if (withoutAt && /[^\w\d]/.test(withoutAt)) {
+          const regex = value.charAt() === '~' ? /\W|^\d+$/ : /\W/;
+          if (withoutAt && regex.test(withoutAt)) {
             resultantValue = `${value.charAt()}"${withoutAt}"`;
           }
         }

changelogs/unreleased/38075_allow_refernce_integer_labels.yml

+---
+title: Fix errors when selecting numeric-only labels in the labels autocomplete selector
+merge_request: 14607
+author: haseebeqx
+type: fixed

spec/features/issues/gfm_autocomplete_spec.rb

@@ -218,6 +218,7 @@ feature 'GFM autocomplete', :js do
       user_item = find('.atwho-view li', text: user.username)
       expect(user_item).to have_content(user.username)
     end
+  end
 
   def expect_to_wrap(should_wrap, item, note, value)
     expect(item).to have_content(value)
@@ -231,5 +232,4 @@ feature 'GFM autocomplete', :js do
       expect(note.value).not_to include("\"#{value}\"")
     end
   end
-  end
 end

spec/javascripts/gfm_auto_complete_spec.js

@@ -67,6 +67,28 @@ describe('GfmAutoComplete', function () {
     });
   });
 
+  describe('DefaultOptions.beforeInsert', () => {
+    const beforeInsert = (context, value) => (
+      gfmAutoCompleteCallbacks.beforeInsert.call(context, value)
+    );
+
+    const atwhoInstance = { setting: { skipSpecialCharacterTest: false } };
+
+    it('should not quote if value only contains alphanumeric charecters', () => {
+      expect(beforeInsert(atwhoInstance, '@user1')).toBe('@user1');
+      expect(beforeInsert(atwhoInstance, '~label1')).toBe('~label1');
+    });
+
+    it('should quote if value contains any non-alphanumeric characters', () => {
+      expect(beforeInsert(atwhoInstance, '~label-20')).toBe('~"label-20"');
+      expect(beforeInsert(atwhoInstance, '~label 20')).toBe('~"label 20"');
+    });
+
+    it('should quote integer labels', () => {
+      expect(beforeInsert(atwhoInstance, '~1234')).toBe('~"1234"');
+    });
+  });
+
   describe('DefaultOptions.matcher', function () {
     const defaultMatcher = (context, flag, subtext) => (
       gfmAutoCompleteCallbacks.matcher.call(context, flag, subtext)