Parsing/Visual Diff Testing/Debugging

Some notes on debugging failures found using visual diff testing.

First: some failures may be transient. Use Parsing/Visual Diff Testing to rerun the tests with a non-perfect visual diff to filter out transients. There may also be some cache issues, perhaps: check that the "Page on the target wikis" link actually shows the same result as the screenshots. If it doesn't, the screenshot may have been a transient or improperly cached result.

Second: the visual diff servers are multiwiki configs. You need to  into them, then ssh into the inner vagrant, *then* use   to select a particular wiki: $ ssh mw-expt.wikitextexp.eqiad.wmflab # or mw-base.wikitextexp.eqiad.wmflabs, or mw-base.eqiad.wmflabs mw-expt$ cd /srv/mediawiki-vagrant/ # code in mediawiki/ and config in settings.d/ mw-expt$ vagrant ssh vagrant$ echo ' Foo ' | mwscript parse.php --wiki=zhwiki

You can also use  to get an REPL with MW loaded.

isn't installed inside vagrant. But  inside vagrant lets you edit it with emacs outside of vagrant.

Other notes:  is unexpanded, because Extension:GeoData is uninstalled

I got a step-by-step dump of templates as they were expanded with this patch, which just basically lets me watch the preprocessor expansion step by step, so i can see at what point weird stuff is introduced: vagrant@mediawiki-vagrant:/vagrant/mediawiki$ git diff diff --git a/includes/parser/Preprocessor_DOM.php b/includes/parser/Preprocessor index 7539307..568198b 100644 --- a/includes/parser/Preprocessor_DOM.php +++ b/includes/parser/Preprocessor_DOM.php @@ -194,6 +194,9 @@ class Preprocessor_DOM extends Preprocessor { */         public function preprocessToXml( $text, $flags = 0 ) { global $wgDisableLangConversion; +echo("\npreprocess start--\n"); +echo($text); +echo("\npreprocess end--\n"); } $forInclusion = $flags & Parser::PTD_FOR_INCLUSION;.