diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index ee41eaa800..b9609a1719 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -576,12 +576,12 @@ function image_form_editor_image_dialog_validate(array &$form, FormStateInterfac
     if ($image_style) {
       $image_style->transformDimensions($dimensions, $attributes['src']);
       $attributes['width'] = $dimensions['width'];
-      $attributes['height'] =  $dimensions['height'];
+      $attributes['height'] = $dimensions['height'];
     }
     else {
-      // We must explicitely set to NULL (and not unset) for CKEditor to take
+      // We must explicitly set to NULL (and not unset) for CKEditor to take
       // the change into account.
-      foreach(['width','height','data-image-style'] as $key) {
+      foreach (['width', 'height', 'data-image-style'] as $key) {
         $attributes[$key] = NULL;
       }
     }
diff --git a/core/modules/image/image.post_update.php b/core/modules/image/image.post_update.php
index 6af171fbad..395d995958 100644
--- a/core/modules/image/image.post_update.php
+++ b/core/modules/image/image.post_update.php
@@ -5,6 +5,7 @@
  * Post-update functions for Image.
  */
 
+use Drupal\Core\Config\Entity\ConfigEntityUpdater;
 use Drupal\filter\FilterFormatInterface;
 
 /**
diff --git a/core/modules/image/tests/src/Functional/FilterImageStyleTest.php b/core/modules/image/tests/src/Functional/FilterImageStyleTest.php
index 7e4f2277a3..dc60f6e5b1 100644
--- a/core/modules/image/tests/src/Functional/FilterImageStyleTest.php
+++ b/core/modules/image/tests/src/Functional/FilterImageStyleTest.php
@@ -36,7 +36,7 @@ class FilterImageStyleTest extends BrowserTestBase {
   /**
    * Tasks common to all tests.
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->format = FilterFormat::create([
@@ -116,7 +116,7 @@ public function testImageStyle() {
     $image_element = $this->getSession()->getPage()->find('css', 'img[data-entity-uuid="' . $file->uuid() . '"]');
     $this->assertNotEmpty($image_element);
 
-    $this->assertContains('medium', $image_element->getAttribute('src'));
+    $this->assertStringContainsString('medium', $image_element->getAttribute('src'));
     $this->assertEquals('220', $image_element->getAttribute('width'));
     $this->assertEquals('164', $image_element->getAttribute('height'));
   }
diff --git a/core/modules/image/tests/src/FunctionalJavascript/AddImageTest.php b/core/modules/image/tests/src/FunctionalJavascript/AddImageTest.php
index fcb5b9eb28..08f29710eb 100644
--- a/core/modules/image/tests/src/FunctionalJavascript/AddImageTest.php
+++ b/core/modules/image/tests/src/FunctionalJavascript/AddImageTest.php
@@ -30,7 +30,7 @@ class AddImageTest extends WebDriverTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     FilterFormat::create([
@@ -101,7 +101,7 @@ public function testDataImageStyleElement() {
     $this->assertNotEmpty($source_button);
     $source_button->click();
 
-    $this->assertContains('data-image-style="thumbnail"', $page->find('css', 'textarea.cke_source')->getValue());
+    $this->assertStringContainsString('data-image-style="thumbnail"', $page->find('css', 'textarea.cke_source')->getValue());
   }
 
 }
diff --git a/core/modules/image/tests/src/Kernel/EditorImageStyleDialogTest.php b/core/modules/image/tests/src/Kernel/EditorImageStyleDialogTest.php
index ed3fb1c245..342ede64a5 100644
--- a/core/modules/image/tests/src/Kernel/EditorImageStyleDialogTest.php
+++ b/core/modules/image/tests/src/Kernel/EditorImageStyleDialogTest.php
@@ -47,7 +47,7 @@ class EditorImageStyleDialogTest extends EntityKernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->installEntitySchema('file');