The test is fragile and breaks when the wiki language is set to any language except English which means it broke travis. An example failure:
https://travis-ci.org/github/wikimedia/mediawiki-extensions-Wikibase/jobs/703626451
1) Wikibase\Lib\Tests\Formatters\NonExistingEntityIdHtmlBrokenLinkFormatterTest::testFormatEntityId with data set #0 (Wikibase\DataModel\Entity\ItemId Object (...), '<a title="someTitle (page doe...n></a>') Failed asserting that two strings are identical. --- Expected +++ Actual @@ @@ -'<a title="someTitle (page does not exist)" href="http://someurl.com" class="new">Q1 <span class="wb-entity-undefinedinfo">(⧼somePrefix-item⧽)</span></a>' +'<a title="someTitle (страница не существует)" href="http://someurl.com" class="new">Q1 <span class="wb-entity-undefinedinfo">(⧼somePrefix-item⧽)</span></a>' /home/travis/build/wikimedia/phase3/extensions/Wikibase/lib/tests/phpunit/Formatters/NonExistingEntityIdHtmlBrokenLinkFormatterTest.php:47 /home/travis/build/wikimedia/phase3/maintenance/doMaintenance.php:105 2) Wikibase\Lib\Tests\Formatters\NonExistingEntityIdHtmlBrokenLinkFormatterTest::testFormatEntityId with data set #1 (Wikibase\DataModel\Entity\PropertyId Object (...), '<a title="someTitle (page doe...n></a>') Failed asserting that two strings are identical. --- Expected +++ Actual @@ @@ -'<a title="someTitle (page does not exist)" href="http://someurl.com" class="new">P99 <span class="wb-entity-undefinedinfo">(⧼somePrefix-property⧽)</span></a>' +'<a title="someTitle (страница не существует)" href="http://someurl.com" class="new">P99 <span class="wb-entity-undefinedinfo">(⧼somePrefix-property⧽)</span></a>' /home/travis/build/wikimedia/phase3/extensions/Wikibase/lib/tests/phpunit/Formatters/NonExistingEntityIdHtmlBrokenLinkFormatterTest.php:47 /home/travis/build/wikimedia/phase3/maintenance/doMaintenance.php:105
Please set the language to qqx in the test class and test with that instead