From 5e10b611299b4a968e51f5a706d60b7d1a9c29b5 Mon Sep 17 00:00:00 2001
From: Antoine Huret <huret.antoine@yahoo.fr>
Date: Mon, 1 Apr 2019 09:09:49 +0000
Subject: [PATCH] add a uniq constraints on issues and mrs labels

---
 app/services/issuable_base_service.rb              |  2 +-
 ...d-uniq-constraints-on-issues-and-mrs-labels.yml |  5 +++++
 spec/services/issues/create_service_spec.rb        | 14 ++++++++++++++
 spec/services/issues/update_service_spec.rb        | 10 ++++++++++
 4 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 changelogs/unreleased/53210-add-uniq-constraints-on-issues-and-mrs-labels.yml

diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 2b2774746a2..95bd83bb03c 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -113,7 +113,7 @@ class IssuableBaseService < BaseService
       new_label_ids -= remove_label_ids if remove_label_ids
     end
 
-    new_label_ids
+    new_label_ids.uniq
   end
 
   def available_labels
diff --git a/changelogs/unreleased/53210-add-uniq-constraints-on-issues-and-mrs-labels.yml b/changelogs/unreleased/53210-add-uniq-constraints-on-issues-and-mrs-labels.yml
new file mode 100644
index 00000000000..f9cd8716b92
--- /dev/null
+++ b/changelogs/unreleased/53210-add-uniq-constraints-on-issues-and-mrs-labels.yml
@@ -0,0 +1,5 @@
+---
+title: add a uniq constraints on issues and mrs labels
+merge_request: 25435
+author: Antoine Huret
+type: fixed
diff --git a/spec/services/issues/create_service_spec.rb b/spec/services/issues/create_service_spec.rb
index 715b1168bfb..d50412b6d2c 100644
--- a/spec/services/issues/create_service_spec.rb
+++ b/spec/services/issues/create_service_spec.rb
@@ -138,6 +138,20 @@ describe Issues::CreateService do
         end
       end
 
+      context 'when duplicate label titles are given' do
+        let(:label) { create(:label, project: project) }
+
+        let(:opts) do
+          { title: 'Title',
+            description: 'Description',
+            labels: [label.title, label.title] }
+        end
+
+        it 'assigns the label once' do
+          expect(issue.labels).to contain_exactly(label)
+        end
+      end
+
       it 'executes issue hooks when issue is not confidential' do
         opts = { title: 'Title', description: 'Description', confidential: false }
 
diff --git a/spec/services/issues/update_service_spec.rb b/spec/services/issues/update_service_spec.rb
index f1684209729..1c8a4b608d5 100644
--- a/spec/services/issues/update_service_spec.rb
+++ b/spec/services/issues/update_service_spec.rb
@@ -592,6 +592,16 @@ describe Issues::UpdateService, :mailer do
           expect(result.label_ids).not_to include(label.id)
         end
       end
+
+      context 'when duplicate label titles are given' do
+        let(:params) do
+          { labels: [label3.title, label3.title] }
+        end
+
+        it 'assigns the label once' do
+          expect(result.labels).to contain_exactly(label3)
+        end
+      end
     end
 
     context 'updating asssignee_id' do