This tests updating link integrity information for all site content, i.e.
after migrating from a previous version.  First we create two sample links and
remove the generated references afterwards:

  >>> self.setRoles(('Manager',))
  >>> portal.doc1.processForm(values={'text':'<a href="doc2">a document</a>'})
  >>> portal.doc2.processForm(values={'text':'<a href="folder1/doc3">a document</a>'})
  >>> portal.doc1.deleteReferences(relationship='isReferencing')
  >>> portal.doc2.deleteReferences(relationship='isReferencing')

Just to make sure, we check that there are no references from or to these
documents at this point:

  >>> self.assertEqual(portal.doc1.getReferences(), [])
  >>> self.assertEqual(portal.doc2.getReferences(), [])

An update of link integrity information for all content is triggered by
browsing a specific url:

  >>> browser = self.getBrowser(loggedIn=True)
  >>> browser.open('http://nohost/plone/updateLinkIntegrityInformation')
  >>> browser.getControl('Update').click()
  >>> browser.contents
  '...<dl class="portalMessage...Link integrity information updated for ... item(s)...</dl>...'

Now the linking documents should hold the correct link integrity references:

  >>> portal.doc1.getReferences()
  [<ATDocument at /plone/doc2>]
  >>> portal.doc2.getReferences()
  [<ATDocument at /plone/folder1/doc3>]

