Add feature spec to verify all 4 different states of closing issues message on...

Add feature spec to verify all 4 different states of closing issues message on Merge Request show page.

spec/features/merge_requests/closes_issues_spec.rb

+require 'spec_helper'
+
+feature 'Merge Commit Description', feature: true do
+  let(:user) { create(:user) }
+  let(:project) { create(:project, :public) }
+  let(:issue_1) { create(:issue, project: project)}
+  let(:issue_2) { create(:issue, project: project)}
+  let(:merge_request) do
+    create(
+      :merge_request,
+      :simple,
+      source_project: project,
+      description: merge_request_description
+    )
+  end
+  let(:merge_request_description) { 'Merge Request Description' }
+
+  before do
+    project.team << [user, :master]
+
+    login_as user
+
+    visit namespace_project_merge_request_path(project.namespace, project, merge_request)
+
+    click_link 'Modify commit message'
+  end
+
+  context 'not closing or mentioning any issue' do
+    it 'does not display closing issue message' do
+      expect(page).not_to have_css('.mr-widget-footer')
+    end
+  end
+
+  context 'closing issues but not mentioning any other issue' do
+    let(:merge_request_description) { "Description\n\nclosing #{issue_1.to_reference}, #{issue_2.to_reference}" }
+
+    it 'does not display closing issue message' do
+      expect(page).to have_content("Accepting this merge request will close issues #{issue_1.to_reference} and #{issue_2.to_reference}")
+    end
+  end
+
+  context 'mentioning issues but not closing them' do
+    let(:merge_request_description) { "Description\n\nRefers to #{issue_1.to_reference} and #{issue_2.to_reference}" }
+
+    it 'does not display closing issue message' do
+      expect(page).to have_content("Issues #{issue_1.to_reference} and #{issue_2.to_reference} are mentioned but will not closed.")
+    end
+  end
+
+  context 'closing some issues and mentioning, but not closing, others' do
+    let(:merge_request_description) { "Description\n\ncloses #{issue_1.to_reference}\n\n refers to #{issue_2.to_reference}" }
+
+    it 'does not display closing issue message' do
+      expect(page).to have_content("Accepting this merge request will close issue #{issue_1.to_reference}. Issue #{issue_2.to_reference} is mentioned but will not closed.")
+    end
+  end
+end