Change record status: 
Project: 
Introduced in branch: 
8.6.x
Introduced in version: 
8.6.2
Description: 

As part of an ongoing effort to isolate PHPUnit-based tests from simpletest, we've deprecated Drupal\field\Tests\EntityReference\EntityReferenceTestTrait.

Test classes using this trait should use Drupal\Tests\field\Traits\EntityReferenceTestTrait instead.