Remove dangling text from suggested branch name

Signed-off-by: Balasankar "Balu" C <balasankar@gitlab.com>

app/models/issue.rb

@@ -206,7 +206,16 @@ class Issue < ApplicationRecord
     if self.confidential?
       "#{iid}-confidential-issue"
     else
-      "#{iid}-#{title.parameterize}"[0, 99]
+      branch_name = "#{iid}-#{title.parameterize}"
+
+      if branch_name.length > 100
+        truncated_string = branch_name[0, 100]
+        # Delete everything dangling after the last hyphen so as not to risk
+        # existence of unintended words in the branch name due to mid-word split.
+        branch_name = truncated_string[0, truncated_string.rindex("-")]
+      end
+
+      branch_name
     end
   end
 

spec/models/issue_spec.rb

@@ -425,10 +425,15 @@ describe Issue do
     end
 
     context 'issue title longer than 100 characters' do
-      let(:issue) { create(:issue, iid: 999, title: 'Lorem ipsum dolor sit amet consectetur adipiscing elit Mauris sit amet ipsum id lacus fringilla convallis') }
+      let(:issue) { create(:issue, iid: 999, title: 'Lorem ipsum dolor sit amet consectetur adipiscing elit Mauris sit amet ipsum id lacus custom fringilla convallis') }
 
-      it "truncates title part of branch name to 100 characters" do
-        expect(issue.to_branch_name).to eq("999-lorem-ipsum-dolor-sit-amet-consectetur-adipiscing-elit-mauris-sit-amet-ipsum-id-lacus-fringilla")
+      it "truncates branch name to at most 100 characters" do
+        expect(issue.to_branch_name.length).to be <= 100
+      end
+
+      it "truncates dangling parts of the branch name" do
+        # 100 characters would've got us "999-lorem...lacus-custom-fri".
+        expect(issue.to_branch_name).to eq("999-lorem-ipsum-dolor-sit-amet-consectetur-adipiscing-elit-mauris-sit-amet-ipsum-id-lacus-custom")
       end
     end
   end