diff --git a/core/tests/Drupal/Tests/Core/EntityReferenceSelection/EntityReferenceSelectionUnitTest.php b/core/tests/Drupal/Tests/Core/EntityReferenceSelection/EntityReferenceSelectionUnitTest.php
index 86aa53e..f0c28e4 100644
--- a/core/tests/Drupal/Tests/Core/EntityReferenceSelection/EntityReferenceSelectionUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/EntityReferenceSelection/EntityReferenceSelectionUnitTest.php
@@ -202,8 +202,16 @@ public function testSetConfigurationBcLevel() {
    * @covers ::resolveBcConfiguration
    */
   public function testDeprecationErrorTriggering() {
-    $config = ['handler_settings' => ['settings1' => TRUE]];
+    // Configuration with no BC level.
+    $config = ['setting1' => TRUE];
     new TestSelection($config, 'test_selector', []);
+    // Check that deprecation errors has not been triggered.
+    $this->assertNoError("Settings under 'handler_settings' are deprecated since version 8.3.x and will be removed before 9.0.0. Move the settings in the root of the configuration array.", E_USER_DEPRECATED);
+
+    // Configuration with BC level.
+    $config = ['handler_settings' => ['setting1' => TRUE]];
+    new TestSelection($config, 'test_selector', []);
+    // Check that deprecation errors has been triggered.
     $this->assertError("Settings under 'handler_settings' are deprecated since version 8.3.x and will be removed before 9.0.0. Move the settings in the root of the configuration array.", E_USER_DEPRECATED);
   }
 
@@ -212,13 +220,13 @@ public function testDeprecationErrorTriggering() {
    *
    * @param string $message
    *   The error message.
-   * @param int $code
-   *   The error code.
+   * @param int $level
+   *   The error level.
    */
-  protected function assertError($message, $code) {
-    $assertion_message = "Triggered error '$message' (code $code).";
+  protected function assertError($message, $level) {
+    $assertion_message = "Triggered error '$message' (level $level).";
     foreach ($this->errors as $error) {
-      if ($error['message'] === $message && $error['code'] == $code) {
+      if ($error['message'] === $message && $error['level'] == $level) {
         $this->assertTrue(TRUE, $assertion_message);
         return;
       }
@@ -227,16 +235,35 @@ protected function assertError($message, $code) {
   }
 
   /**
+   * Asserts a specific error has not been triggered.
+   *
+   * @param string $message
+   *   The error message.
+   * @param int $level
+   *   The error level.
+   */
+  protected function assertNoError($message, $level) {
+    $assertion_message = "Not triggered error '$message' (level $level) .";
+    foreach ($this->errors as $error) {
+      if ($error['message'] === $message && $error['level'] == $level) {
+        $this->fail($assertion_message);
+        return;
+      }
+    }
+    $this->assertTrue(TRUE, $assertion_message);
+  }
+
+  /**
    * Provides a testing error handler.
    *
-   * @param int $code
+   * @param int $level
    * @param string $message
    * @param string $file
    * @param int $line
    * @param array $context
    */
-  public function errorHandler($code, $message, $file, $line, $context) {
-    $this->errors[] = compact('code', 'message', 'file', 'line', 'context');
+  public function errorHandler($level, $message, $file, $line, $context) {
+    $this->errors[] = compact('level', 'message', 'file', 'line', 'context');
   }
 
 }