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fix: allow ARIA headings in EDUPUB (legacy profile)
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This commit fixes the legacy EDUPUB checks by allowing ARIA headings along with native h1-h6 headings.

Note: EDUPUB support is a legacy feature of EPUBCheck, since the standard is not actively maintained.

Fix #1483
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@rdeltour
rdeltour committed Apr 21, 2023
1 parent 199da0b commit da4f541
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166 changes: 111 additions & 55 deletions src/main/resources/com/adobe/epubcheck/schema/30/edupub/edu-structure.sch
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Expand Up @@ -2,92 +2,148 @@
<schema xmlns="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<ns uri="http://www.idpf.org/2007/ops" prefix="epub"/>
<ns uri="http://www.w3.org/1999/xhtml" prefix="html"/>

<!-- following variable declarations are used to test h# nesting depth -->
<!-- checks if the body contains anything other than a single section or article - i.e., is it an implied section
- previously tested if >1 article/section children with : or count(//html:body/child::html:*[self::html:article or self::html:section]) &gt; 1
but ambiguous whether multiple section elements is an implied body or just a weird breakup of the file
-->
<let name="body-is-section" value="exists(//html:body/(html:* except (html:article|html:section)))"/>

<let name="body-is-section"
value="exists(//html:body/(html:* except (html:article | html:section)))"/>

<!-- check if implied heading -->
<let name="body-label-len" value="string-length(normalize-space(//html:body/@aria-label))"/>

<!-- finds the topmost heading in the file that is the descendant of the body (not sectioning element ancestors) or the first descendant of a section or article -->
<let name="topmost-heading" value="//html:body//(html:h1|html:h2|html:h3|html:h4|html:h5|html:h6)[not(ancestor::html:aside|ancestor::html:nav) and count(ancestor::html:section|ancestor::html:article) le 1]"/>

<let name="topmost-heading"
value="//html:body//(html:h1 | html:h2 | html:h3 | html:h4 | html:h5 | html:h6 | html:*[@role = 'heading'])[not(ancestor::html:aside | ancestor::html:nav) and count(ancestor::html:section | ancestor::html:article) le 1]"/>

<!-- extract the starting rank from the topmost-heading -->
<let name="topmost-heading-rank" value="if ($body-label-len &gt; 0) then 1 else if (exists($topmost-heading)) then number(substring(name($topmost-heading[1]),2)) else 1"/>

<let name="topmost-heading-rank" value="
if ($body-label-len &gt; 0) then
1
else
if (exists($topmost-heading)) then
if ($topmost-heading[1][@role = 'heading']) then
if ($topmost-heading[1]/@aria-level) then
number($topmost-heading[1]/@aria-level)
else
2
else
number(substring(name($topmost-heading[1]), 2))
else
1"/>

<!-- find the nesting depth of the topmost heading (0 if body, 1 if a section or article around it) -->
<let name="topmost-heading-nest" value="if ($body-label-len &gt; 0) then 0 else if (empty($topmost-heading[1]/(ancestor::html:section|ancestor::html:article|ancestor::html:nav))) then 0 else 1"/>


<let name="topmost-heading-nest" value="
if ($body-label-len &gt; 0) then
0
else
if (empty($topmost-heading[1]/(ancestor::html:section | ancestor::html:article | ancestor::html:nav))) then
0
else
1"/>


<pattern id="edupub.headings">
<rule context="html:body[html:* except (html:article|html:section|html:aside|html:nav)]">
<let name="headings" value=".//(html:h1|html:h2|html:h3|html:h4|html:h5|html:h6)[empty(ancestor::html:section|ancestor::html:aside|ancestor::html:article|ancestor::html:nav)]"/>

<rule context="html:body[html:* except (html:article | html:section | html:aside | html:nav)]">
<let name="headings"
value=".//(html:h1 | html:h2 | html:h3 | html:h4 | html:h5 | html:h6 | html:*[@role = 'heading'])[empty(ancestor::html:section | ancestor::html:aside | ancestor::html:article | ancestor::html:nav)]"/>

<report test="@aria-label and $body-label-len = 0">Empty aria-label attribute found.</report>

<assert test="$body-label-len &gt; 0 or count($headings) &gt; 0">The body element requires a heading when it is used as an implied section.</assert>


<assert test="$body-label-len &gt; 0 or count($headings) &gt; 0">The body element requires a
heading when it is used as an implied section.</assert>

<!-- <report test="$arialabel-len &gt; 0 and count($headings) &gt; 0">The aria-label attribute must not be mixed with ranked headings.</report> -->

<report test="count($headings) &gt; 1">More than one ranked heading found as direct descendant of body.</report>

<report test="count($headings) = 1 and string-length(normalize-space(string-join($headings|$headings/html:img/@alt|$headings//@aria-label))) = 0">Empty ranked heading detected.</report>

<report test="@aria-label and (normalize-space($headings) = normalize-space(@aria-label))">The value of the "aria-label" attribute must not be the same as the content of the heading.</report>

<report test="count($headings) &gt; 1">More than one ranked heading found as direct descendant
of body.</report>

<report
test="count($headings) = 1 and string-length(normalize-space(string-join($headings | $headings/html:img/@alt | $headings//@aria-label))) = 0"
>Empty ranked heading detected.</report>

<report test="@aria-label and (normalize-space($headings) = normalize-space(@aria-label))">The
value of the "aria-label" attribute must not be the same as the content of the
heading.</report>
</rule>
<rule context="html:section|html:article">


<rule context="html:section | html:article">
<let name="arialabel-len" value="string-length(normalize-space(@aria-label))"/>
<let name="headings" value=".//(html:h1|html:h2|html:h3|html:h4|html:h5|html:h6)[(ancestor::html:section|ancestor::html:article|ancestor::html:aside|ancestor::html:nav)[last()] = current()]"/>

<let name="headings"
value=".//(html:h1 | html:h2 | html:h3 | html:h4 | html:h5 | html:h6 | html:*[@role = 'heading'])[(ancestor::html:section | ancestor::html:article | ancestor::html:aside | ancestor::html:nav)[last()] = current()]"/>

<report test="@aria-label and $arialabel-len = 0">Empty aria-label attribute found.</report>

<assert test="$arialabel-len &gt; 0 or count($headings) &gt; 0"><value-of select="name()"/> does not have a heading.</assert>


<assert test="$arialabel-len &gt; 0 or count($headings) &gt; 0"><value-of select="name()"/>
does not have a heading.</assert>

<!-- <report test="$arialabel-len &gt; 0 and count($headings) &gt; 0">The aria-label attribute must not be mixed with ranked headings.</report> -->

<report test="count($headings) &gt; 1">More than one ranked heading found as direct descendant of <value-of select="name()"/>.</report>

<report test="count($headings) = 1 and string-length(normalize-space(string-join($headings|$headings/html:img/@alt|$headings//@aria-label))) = 0">Empty ranked heading detected.</report>

<report test="@aria-label and (normalize-space($headings) = normalize-space(@aria-label))">The value of the "aria-label" attribute must not be the same as the content of the heading.</report>

<report test="count($headings) &gt; 1">More than one ranked heading found as direct descendant
of <value-of select="name()"/>.</report>

<report
test="count($headings) = 1 and string-length(normalize-space(string-join($headings | $headings/html:img/@alt | $headings//@aria-label))) = 0"
>Empty ranked heading detected.</report>

<report test="@aria-label and (normalize-space($headings) = normalize-space(@aria-label))">The
value of the "aria-label" attribute must not be the same as the content of the
heading.</report>
</rule>

<rule context="html:h1|html:h2|html:h3|html:h4|html:h5|html:h6">

<rule
context="html:h1 | html:h2 | html:h3 | html:h4 | html:h5 | html:h6 | html:*[@role = 'heading']">
<!-- get the # from the h# tag found -->
<let name="current-rank" value="number(substring(name(current()),2))"/>

<let name="current-rank" value="
if (current()[@role = 'heading']) then
if (current()/@aria-level) then
number(current()/@aria-level)
else
2
else
number(substring(name(current()), 2))"/>

<!-- find nesting depth -->
<let name="current-nesting" value="count(ancestor::html:section|ancestor::html:article|ancestor::html:aside|ancestor::html:nav)"/>

<let name="current-nesting"
value="count(ancestor::html:section | ancestor::html:article | ancestor::html:aside | ancestor::html:nav)"/>

<!-- derive the expected rank of this heading from the implied body or sectioning -->
<let name="expected-rank" value="if ($body-is-section) then $topmost-heading-rank - $topmost-heading-nest + $current-nesting else $topmost-heading-rank + $current-nesting - 1"/>

<let name="expected-rank" value="
if ($body-is-section) then
$topmost-heading-rank - $topmost-heading-nest + $current-nesting
else
$topmost-heading-rank + $current-nesting - 1"/>

<!-- report ranked headings in sectioning roots -->
<report test="ancestor::html:figure or ancestor::html:blockquote">Ranked headings are not valid in figure or blockquote</report>

<report test="ancestor::html:figure or ancestor::html:blockquote">Ranked headings are not
valid in figure or blockquote</report>

<!-- if the expected rank is below 6, check that it matches what is expected -->
<report test="$expected-rank &lt; 6 and not($current-rank = $expected-rank)">The heading rank h<value-of select="$current-rank"/> does not match the current nesting level (<value-of select="$expected-rank"/>).</report>

<report test="$expected-rank &lt; 6 and not($current-rank = $expected-rank)">The heading rank
h<value-of select="$current-rank"/> does not match the current nesting level (<value-of
select="$expected-rank"/>).</report>

<!-- otherwise, just stop testing after 5 and report any headings that aren't six, since no higher exist -->
<report test="$expected-rank &gt; 5 and $current-rank &lt; 6">The current heading rank should be h6.</report>
<report test="$expected-rank &gt; 5 and $current-rank &lt; 6">The current heading rank should
be h6.</report>
</rule>
</pattern>

<pattern id="edupub.sectioning">
<rule context="*[parent::html:body or parent::html:section][not(self::html:section)]">
<report test="preceding-sibling::html:section">Non-section elements not allowed between or after section elements.</report>
<report test="preceding-sibling::html:section">Non-section elements not allowed between or
after section elements.</report>
</rule>
</pattern>

<pattern id="edupub.subtitles">
<rule context="html:p[@epub:type='subtitle'][preceding-sibling::*[self::html:h1|self::html:h2|self::html:h3|self::html:h4|self::html:h5|self::html:h6]]">
<assert test="ancestor::html:header">Section subtitles must be wrapped in a header element.</assert>
<rule
context="html:p[@epub:type = 'subtitle'][preceding-sibling::*[self::html:h1 | self::html:h2 | self::html:h3 | self::html:h4 | self::html:h5 | self::html:h6]]">
<assert test="ancestor::html:header">Section subtitles must be wrapped in a header
element.</assert>
</rule>
</pattern>
</schema>
31 changes: 19 additions & 12 deletions src/test/resources/epub-edupub/edupub-content-document-xhtml.feature
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Expand Up @@ -41,6 +41,25 @@ Feature: EPUB for Education ▸ XHTML Content Document Checks
And the message contains 'The body element requires a heading when it is used as an implied section'
And no other errors or warnings are reported

Scenario: Report a missing section heading
When checking document 'edupub-heading-missing-error.xhtml'
Then error RSC-005 is reported
And the message contains 'section does not have a heading'
But no other errors or warnings are reported

Scenario: Allow a section heading specified as ARIA heading role
When checking document 'edupub-heading-aria-role-valid.xhtml'
Then no errors or warnings are reported

Scenario: Verify a heading with only an `img` that has alternative text
When checking document 'edupub-heading-img-alt-valid.xhtml'
Then no errors or warnings are reported

Scenario: Report a heading with only an `img` without alternative text
When checking document 'edupub-heading-img-no-alt-error.xhtml'
Then error RSC-005 is reported
And the message contains 'Empty ranked heading detected'
And no other errors or warnings are reported

## 4.3 Titles and Headings

Expand Down Expand Up @@ -84,15 +103,3 @@ Feature: EPUB for Education ▸ XHTML Content Document Checks
And no other errors or warnings are reported


# No matching section

Scenario: Verify a heading with only an `img` that has alternative text
When checking document 'edupub-heading-img-alt-valid.xhtml'
Then no errors or warnings are reported

Scenario: Report a heading with only an `img` without alternative text
When checking document 'edupub-heading-img-no-alt-error.xhtml'
Then error RSC-005 is reported
And the message contains 'Empty ranked heading detected'
And no other errors or warnings are reported

12 changes: 12 additions & 0 deletions ...t/resources/epub-edupub/files/content-document-xhtml/edupub-heading-aria-role-valid.xhtml
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@@ -0,0 +1,12 @@
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Test</title>
<meta charset="UTF-8" />
</head>
<body>
<section>
<span aria-level="1" role="heading">Heading</span>
</section>
</body>
</html>
12 changes: 12 additions & 0 deletions ...est/resources/epub-edupub/files/content-document-xhtml/edupub-heading-missing-error.xhtml
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@@ -0,0 +1,12 @@
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Test</title>
<meta charset="UTF-8" />
</head>
<body>
<section>
<!--<h1>Test</h1>-->
</section>
</body>
</html>

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