test/extensions/setext_headers_with_ids.unit

>>> h1
text
===

<<<
<h1 id="text">text</h1>
>>> h2
text
---

<<<
<h2 id="text">text</h2>
>>> header with inline syntax
header *emphasised*
===

<<<
<h1 id="header-emphasised">header <em>emphasised</em></h1>