We should be making sure HTML tags are opened, closed and nested properly, but we shouldn't prevent open/close pairs from being moved around.

Change html/xml validator to flag improper nesting of tags (i.e. more sophisticated nesting)

  1. "<a>hello</a>" to "</a>hi<a>" gives error that opening and closing tags have been swapped.
  2. "<a>hello <b>world</b></a>" to "<a>hi <b>world</a></b>" gives error that tags are not properly nested.
  3. "<a>hello world</a>" to "<a>hi <b>world</b></a>" gives a warning about unknown tag being added (unknown tag but properly nested).
  4. "world.</a><b>something</b>" to "world.<b></a>something</b>" gives error that tags are not properly nested.
  5. "<a>hello</a><b>worl" to "<a>hi<b></a>worl" gives error that tags are not properly nested.
  6. "<a>hello<b></a>world</b>" to "<a>hi<b></a>world</b>" gives an error that the nesting is invalid, with a note that the source was not properly nested
  7. "</a></b> Hello world" to "</b></a> Hi world" gives an error that tags are not properly nested.
  8. "Hello <a><b>world" to "Hi <b><a>world" gives a warning that there may be improper nesting. Note that in html5, it is valid to have opening tags for some specific elements that are not paired with closing tags (e.g. <li>), so an error is not appropriate.
  9. "<a>Hello<br/>world</a>" to "<a>Hello world</a><br/>" gives a warning because the nesting has changed. Note: only add this if it is easy to add.
  10. "<a>Hello<b>world</b></a>" to "<a>Hello </a><b>world</b>" gives a warning because the nesting has changed. Note: only add this if it is easy to add.

Migrated; check JIRA for bug status: http://zanata.atlassian.net/browse/ZNTA-549