Fix unit tests after [35739]

[ocean90]

Looks like we have some theme-dependent tests which are failing now.

​https://travis-ci.org/aaronjorbin/develop.wordpress/jobs/93252288

[ocean90]

cc: @joemcgill, @obenland, @westonruter

[danielbachhuber]

I might suggest not loading a theme when running core unit tests, to prevent the active theme from ever affecting expected core behavior.

[obenland]

https://core.trac.wordpress.org/browser/trunk/tests/phpunit/tests/customize/widgets.php?rev=35724#L39

The easy way would to change the filter to twentysixteen_setup, or we could work on that @todo like Daniel mentioned.

[joemcgill]

Fix responsive image tests after Twenty Sixteen

[joemcgill]

34790.diff modifies the responsive image tests that were failing after the switch to Twenty Sixteen as the default theme. If we truly want to be able to run these tests without any interference from whichever theme is loaded, we'd need to mock all of the expected data for image uploads, rather than using the current factory methods to create actual attachments from uploaded data.

[westonruter]

Replying to danielbachhuber:

I might suggest not loading a theme when running core unit tests, to prevent the active theme from ever affecting expected core behavior.

+1. See #31550. Unfortunately I won't be at a keyboard until Friday night (PST) at the earliest.

[wonderboymusic]

In 35751:

Unit Tests: fix responsive image unit tests. Correct the logic in video shortcode unit test for width.

Props joemcgill, wonderboymusic.
Fixes #34790.