Fix frozen string error

spec/features/projects/commits/user_browses_commits_spec.rb

@@ -13,7 +13,7 @@ describe 'User browses commits' do
   it 'renders commit' do
     visit project_commit_path(project, sample_commit.id)
 
-    expect(page).to have_content(sample_commit.message.gsub!(/\s+/, ' '))
+    expect(page).to have_content(sample_commit.message.gsub(/\s+/, ' '))
       .and have_content("Showing #{sample_commit.files_changed_count} changed files")
       .and have_content('Side-by-side')
   end

spec/support/helpers/api_helpers.rb

@@ -32,12 +32,13 @@ module ApiHelpers
     end
 
     if query_string
-      full_path << (path.index('?') ? '&' : '?')
-      full_path << query_string
-    end
+      separator = path.index('?') ? '&' : '?'
 
+      full_path + separator + query_string
+    else
       full_path
     end
+  end
 
   def expect_paginated_array_response(items)
     expect(response).to have_gitlab_http_status(200)