.../rest/tests/modules/rest_test/rest_test.module   | 17 +++++++++--------
 .../EntityResource/EntityResourceTestBase.php       | 21 +--------------------
 2 files changed, 10 insertions(+), 28 deletions(-)

diff --git a/core/modules/rest/tests/modules/rest_test/rest_test.module b/core/modules/rest/tests/modules/rest_test/rest_test.module
index 7ee3aa6..197b82f 100644
--- a/core/modules/rest/tests/modules/rest_test/rest_test.module
+++ b/core/modules/rest/tests/modules/rest_test/rest_test.module
@@ -35,13 +35,14 @@ function rest_test_entity_field_access($operation, FieldDefinitionInterface $fie
 }
 
 /**
- * Implements hook_entity_bundle_field_info_alter().
- *
- * @see \Drupal\Tests\rest\Functional\EntityResource\EntityResourceTestBase::setUp()
- * @todo Remove this in https://www.drupal.org/node/2905890.
+ * Implements hook_entity_base_field_info().
  */
-function rest_test_entity_bundle_field_info_alter(&$fields, EntityTypeInterface $entity_type, $bundle) {
-  if (!empty($fields['rest_test_validation'])) {
-    $fields['rest_test_validation']->addConstraint('rest_test_validation', []);
-  }
+function rest_test_entity_base_field_info(EntityTypeInterface $entity_type) {
+  $fields = [];
+  $fields['rest_test_validation'] = BaseFieldDefinition::create('string')
+    ->setLabel(t('REST test validation field'))
+    ->setDescription(t('A text field with some special validations attached used for testing purposes'))
+    ->addConstraint('rest_test_validation');
+
+  return $fields;
 }
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index 9517b62..cfa9d1a 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -180,26 +180,7 @@ public function setUp() {
         ->setTranslatable(FALSE)
         ->save();
 
-      // Add field for testing validation.
-      // @see rest_test_entity_bundle_field_info_alter()
-      FieldStorageConfig::create([
-        'entity_type' => static::$entityTypeId,
-        'field_name' => 'rest_test_validation',
-        'type' => 'string',
-      ])
-        ->setCardinality(2)
-        ->save();
-      FieldConfig::create([
-        'entity_type' => static::$entityTypeId,
-        'field_name' => 'rest_test_validation',
-        'bundle' => $this->entity->bundle(),
-        'description' => 'A text field with some special validations attached used for testing purposes',
-      ])
-        ->setLabel('REST test validation field')
-        ->setTranslatable(FALSE)
-        ->save();
-
-      // Reload entity so that it has the new fields.
+      // Reload entity so that it has the new field.
       $this->entity = $this->entityStorage->loadUnchanged($this->entity->id());
 
       // Set a default value on the field.