<gallery> File:Image_Not_Found.jpg </gallery>
In PHP this generates a span containing Image Not Found.jpg whereas in Parsoid it generates File:Image_Not_Found.jpg
Including the namespace prefix is consistent with image syntax, so if we want to change the gallery output in this way I wouldn't complain, but you could also argue that in a gallery context the prefix is not necessary. Either way the title should be normalised to remove underscores for readability and word-wrapping issues.
Also how is one supposed to access the image resource from the DOM in this case? Also the alt text is missing...
<li class="gallerybox" style="width: 155px;">
<div class="thumb" style="width: 150px; height: 150px;">
<span style="display: inline-block; height: 100%; vertical-align: middle;"></span>
<span style="vertical-align: middle; display: inline-block;">File:Image_Not_Found.jpg</span>
</div>
<div class="gallerytext"></div>
</li>Change 363654 had a related patch set uploaded (by Arlolra; owner: Arlolra):
[mediawiki/services/parsoid@master] [WIP] T169342: Make gallery output for missing images consistent with php
Also how is one supposed to access the image resource from the DOM in this case?
See L277 here, https://gerrit.wikimedia.org/r/#/c/363654/2/lib/ext/Gallery/index.js where the assumption is that if a .thumb element renders without media, then it's the textContent.
But maybe it's preferable to not suppress the mw:Error?
<span typeof="mw:Error mw:Image" style="vertical-align: middle; display: inline-block;"><a href="./File:Image_Not_Found.jpg"><img resource="./File:Image_Not_Found.jpg" src="./Special:FilePath/Image_Not_Found.jpg" height="120" width="120"/></a></span>
Though that's more of a divergence from php.
Also the alt text is missing...
I take it you mean,
<gallery> File:Image_Not_Found.jpg|alt=123123 </gallery>
The latter option is perhaps better in this case,
<span typeof="mw:Error mw:Image" style="vertical-align: middle; display: inline-block;"><a href="./File:Image_Not_Found.jpg"><img alt="123123" resource="./File:Image_Not_Found.jpg" src="./Special:FilePath/Image_Not_Found.jpg" height="120" width="120"/></a></span>
The same is true of |link=haha.com,
<span typeof="mw:Error mw:Image" style="vertical-align: middle; display: inline-block;"><a href="http://haha.com"><img alt="123123" resource="./File:Image_Not_Found.jpg" src="./Special:FilePath/Image_Not_Found.jpg" height="120" width="120"/></a></span>
Yes - I suppose plain images already diverge from PHP in this way already (rendering a missing image instead of text).
For the time being it would hurt to be the same as the normal image handler, but we should re-consider this behaviour before switching read mode to Parsoid, as rendering a missing image tag does not convey the same information as saying "this image does not exist (or has been deleted)": a missing image tag could just be an intermittent network error.
Change 363654 merged by jenkins-bot:
[mediawiki/services/parsoid@master] T169342: Render missing gallery images the same as plain
Mentioned in SAL (#wikimedia-operations) [2017-09-06T20:34:14Z] <arlolra> Updated Parsoid to f9d367ea (T169342)