diff -u b/core/modules/node/src/Tests/Migrate/d6/MigrateNodeBuilderTest.php b/core/modules/node/src/Tests/Migrate/d6/MigrateNodeBuilderTest.php
--- b/core/modules/node/src/Tests/Migrate/d6/MigrateNodeBuilderTest.php
+++ b/core/modules/node/src/Tests/Migrate/d6/MigrateNodeBuilderTest.php
@@ -34,7 +34,7 @@
   protected function assertEntity($id, $label) {
     $migration = $this->builtMigrations[$id];
     $this->assertTrue($migration instanceof Migration);
-    $this->assertEqual($id, $migration->id());
+    $this->assertIdentical($id, $migration->id());
     $this->assertEqual($label, $migration->label());
   }
 
diff -u b/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
--- b/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -30,6 +30,7 @@
 
   use SessionTestTrait;
   use RandomGeneratorTrait;
+  use AssertionHelperTrait;
 
   /**
    * The test run ID.
@@ -690,29 +691,6 @@
   }
 
   /**
-   * Casts SafeStringInterface objects into strings.
-   *
-   * @param string|array $value
-   *   The value to act on.
-   *
-   * @return mixed
-   *   The input value, with SafeStringInterface objects casted to string.
-   */
-  protected function castSafeStrings($value) {
-    if ($value instanceof SafeStringInterface) {
-      $value = (string) $value;
-    }
-    if (is_array($value)) {
-      array_walk_recursive($value, function (&$item) {
-        if ($item instanceof SafeStringInterface) {
-          $item = (string) $item;
-        }
-      });
-    }
-    return $value;
-  }
-
-  /**
    * Check to see if two values are identical.
    *
    * @param $first
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/simpletest/src/AssertionHelperTrait.php
@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\simpletest\AssertionHelperTrait.
+ */
+
+namespace Drupal\simpletest;
+
+/**
+ * Provides helper methods for assertions.
+ */
+trait AssertionHelperTrait {
+
+  /**
+   * Casts SafeStringInterface objects into strings.
+   *
+   * @param string|array $value
+   *   The value to act on.
+   *
+   * @return mixed
+   *   The input value, with SafeStringInterface objects casted to string.
+   */
+  protected function castSafeStrings($value) {
+    if ($value instanceof SafeStringInterface) {
+      $value = (string) $value;
+    }
+    if (is_array($value)) {
+      array_walk_recursive($value, function (&$item) {
+        if ($item instanceof SafeStringInterface) {
+          $item = (string) $item;
+        }
+      });
+    }
+    return $value;
+  }
+
+}
only in patch2:
unchanged:
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -52,6 +52,7 @@
 
   use AssertLegacyTrait;
   use AssertContentTrait;
+  use AssertionHelperTrait;
   use RandomGeneratorTrait;
 
   /**