--- /dev/null
+<?php
+
+namespace Drupal\diff\Tests;
+
+/**
+ * Tests the Diff module plugins.
+ *
+ * @ingroup diff
+ */
+abstract class DiffPluginTestBase extends DiffTestBase {
+
+ /**
+ * Modules to enable.
+ *
+ * @var array
+ */
+ public static $modules = [
+ 'diff_test',
+ 'link',
+ 'options',
+ ];
+
+ /**
+ * A storage instance for the entity form display.
+ *
+ * @var \Drupal\Core\Entity\Display\EntityFormDisplayInterface
+ */
+ protected $formDisplay;
+
+ /**
+ * A storage instance for the entity view display.
+ *
+ * @var \Drupal\Core\Entity\Display\EntityViewDisplayInterface
+ */
+ protected $viewDisplay;
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+
+ $this->formDisplay = \Drupal::entityTypeManager()->getStorage('entity_form_display');
+ $this->viewDisplay = \Drupal::entityTypeManager()->getStorage('entity_view_display');
+
+ $this->drupalLogin($this->rootUser);
+ }
+
+}