Add tests for label prioritization

spec/features/projects/labels/update_prioritization_spec.rb

+require 'spec_helper'
+
+feature 'Prioritize labels', feature: true do
+  include WaitForAjax
+
+  let(:user)    { create(:user) }
+  let(:project) { create(:project, name: 'test', namespace: user.namespace) }
+
+  scenario 'user can prioritize a label', js: true do
+    bug     = create(:label, title: 'bug')
+    wontfix = create(:label, title: 'wontfix')
+
+    project.labels << bug
+    project.labels << wontfix
+
+    login_as user
+    visit namespace_project_labels_path(project.namespace, project)
+
+    expect(page).to have_content('No prioritized labels yet')
+
+    page.within('.other-labels') do
+      first('.js-toggle-priority').click
+      wait_for_ajax
+      expect(page).not_to have_content('bug')
+    end
+
+    page.within('.prioritized-labels') do
+      expect(page).not_to have_content('No prioritized labels yet')
+      expect(page).to have_content('bug')
+    end
+  end
+
+  scenario 'user can unprioritize a label', js: true do
+    bug     = create(:label, title: 'bug', priority: 1)
+    wontfix = create(:label, title: 'wontfix')
+
+    project.labels << bug
+    project.labels << wontfix
+
+    login_as user
+    visit namespace_project_labels_path(project.namespace, project)
+
+    expect(page).to have_content('bug')
+
+    page.within('.prioritized-labels') do
+      first('.js-toggle-priority').click
+      wait_for_ajax
+      expect(page).not_to have_content('bug')
+    end
+
+    page.within('.other-labels') do
+      expect(page).to have_content('bug')
+      expect(page).to have_content('wontfix')
+    end
+  end
+
+  scenario 'user can sort prioritized labels', js: true do
+    bug     = create(:label, title: 'bug', priority: 1)
+    wontfix = create(:label, title: 'wontfix', priority: 2)
+
+    project.labels << bug
+    project.labels << wontfix
+
+    login_as user
+    visit namespace_project_labels_path(project.namespace, project)
+
+    expect(page).to have_content 'bug'
+    expect(page).to have_content 'wontfix'
+
+    # Sort labels
+    find("#label_#{bug.id}").drag_to find("#label_#{wontfix.id}")
+
+    page.within('.prioritized-labels') do
+      expect(first('li')).to have_content('wontfix')
+      expect(page.all('li').last).to have_content('bug')
+    end
+  end
+end