Fix Piwik not working

Due to indentation, the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31402 broke the
templating of Piwik script header.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/66627

app/views/layouts/_piwik.html.haml

@@ -11,5 +11,5 @@
       var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
       g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
     })();
-  <noscript><p><img src="//#{extra_config.piwik_url}/piwik.php?idsite=#{extra_config.piwik_site_id}" style="border:0;" alt="" /></p></noscript>
-  <!-- End Piwik Code -->
+<noscript><p><img src="//#{extra_config.piwik_url}/piwik.php?idsite=#{extra_config.piwik_site_id}" style="border:0;" alt="" /></p></noscript>
+<!-- End Piwik Code -->

changelogs/unreleased/sh-fix-piwik-template.yml

+---
+title: Fix Piwik not working
+merge_request: 32234
+author:
+type: fixed

spec/views/layouts/_head.html.haml_spec.rb

 require 'spec_helper'
 
 describe 'layouts/_head' do
+  include StubConfiguration
+
   before do
     allow(view).to receive(:current_application_settings).and_return(Gitlab::CurrentSettings.current_application_settings)
   end
@@ -87,6 +89,24 @@ describe 'layouts/_head' do
     end
   end
 
+  context 'when a Piwik config is set' do
+    let(:piwik_host) { 'piwik.example.com' }
+
+    before do
+      stub_config(extra: {
+                    piwik_url: piwik_host,
+                    piwik_site_id: 12345
+                  })
+    end
+
+    it 'add a Piwik Javascript' do
+      render
+
+      expect(rendered).to match(/<script.*>.*var u="\/\/#{piwik_host}\/".*<\/script>/m)
+      expect(rendered).to match(%r(<noscript>.*<img src="//#{piwik_host}/piwik.php.*</noscript>))
+    end
+  end
+
   def stub_helper_with_safe_string(method)
     allow_any_instance_of(PageLayoutHelper).to receive(method)
       .and_return(%q{foo" http-equiv="refresh}.html_safe)