diff -u b/core/modules/media/tests/src/Kernel/MediaSourceTest.php b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
--- b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
+++ b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
@@ -176,7 +176,7 @@
     $media->save();
     $this->assertSame('public://thumbnail1.jpg', $media->thumbnail->entity->getFileUri(), 'Thumbnail was not added to the media item.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Now change the metadata attribute and make sure that the thumbnail stays
     // the same.
@@ -187,7 +187,7 @@
     $media->save();
     $this->assertSame('public://thumbnail1.jpg', $media->thumbnail->entity->getFileUri(), 'Thumbnail was not preserved.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Remove the thumbnail and make sure that it is auto-updated on save.
     $media->thumbnail->target_id = NULL;
@@ -195,7 +195,7 @@
     $media->save();
     $this->assertSame('public://thumbnail2.jpg', $media->thumbnail->entity->getFileUri(), 'New thumbnail was not added to the media item.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Change the metadata attribute again, change the source field value too
     // and make sure that the thumbnail updates.
@@ -207,7 +207,7 @@
     $media->save();
     $this->assertSame('public://thumbnail1.jpg', $media->thumbnail->entity->getFileUri(), 'New thumbnail was not added to the media item.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Change the thumbnail metadata attribute and make sure that the thumbnail
     // is set correctly.
@@ -227,7 +227,7 @@
     $media->save();
     $this->assertSame('public://thumbnail2.jpg', $media->thumbnail->entity->getFileUri(), 'Correct metadata attribute was not used for the thumbnail.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Enable queued thumbnails and make sure that the entity gets the default
     // thumbnail initially.
@@ -245,7 +245,7 @@
     $media->save();
     $this->assertSame('public://media-icons/generic/generic.png', $media->thumbnail->entity->getFileUri(), 'Default thumbnail was not set initially.');
     $this->assertSame('Mr. Jones', $media->thumbnail->title, 'Title text was not set on the thumbnail.');
-    $this->assertSame('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
+    $this->assertEquals('Thumbnail', $media->thumbnail->alt, 'Alt text was not set on the thumbnail.');
 
     // Process the queue item and make sure that the thumbnail was updated too.
     $queue_name = 'media_entity_thumbnail';
@@ -309,7 +309,7 @@
     /** @var \Drupal\Core\Entity\EntityConstraintViolationListInterface $violations */
     $violations = $media->validate();
     $this->assertCount(1, $violations, 'Expected number of validations not found.');
-    $this->assertSame('Inappropriate text.', $violations->get(0)->getMessage(), 'Incorrect constraint validation message found.');
+    $this->assertEquals('Inappropriate text.', $violations->get(0)->getMessage(), 'Incorrect constraint validation message found.');
 
     // Fix the violation and make sure it is not reported anymore.
     $media->setName('I love Drupal!');
@@ -341,7 +341,7 @@
     /** @var \Drupal\Core\Entity\EntityConstraintViolationListInterface $violations */
     $violations = $media->validate();
     $this->assertCount(1, $violations, 'Expected number of validations not found.');
-    $this->assertSame('Inappropriate text.', $violations->get(0)->getMessage(), 'Incorrect constraint validation message found.');
+    $this->assertEquals('Inappropriate text.', $violations->get(0)->getMessage(), 'Incorrect constraint validation message found.');
 
     // Fix the violation and make sure it is not reported anymore.
     $media->set('field_media_test_constraints', 'I love Drupal!');
@@ -382,7 +382,7 @@
     $this->assertSame('field_media_test_1', $field->getName(), 'Incorrect field name is used.');
     $this->assertSame('string', $field->getType(), 'Field is of incorrect type.');
     $this->assertTrue($field->isRequired(), 'Field is not required.');
-    $this->assertSame('Test source', $field->label(), 'Incorrect label is used.');
+    $this->assertEquals('Test source', $field->label(), 'Incorrect label is used.');
     $this->assertSame('test_type', $field->getTargetBundle(), 'Field is not targeting correct bundle.');
 
     // Fields should be automatically saved only when creating the media type
@@ -417,7 +417,7 @@
     $this->assertSame('field_media_test_constraints_1', $field->getName(), 'Incorrect field name is used.');
     $this->assertSame('string_long', $field->getType(), 'Field is of incorrect type.');
     $this->assertTrue($field->isRequired(), 'Field is not required.');
-    $this->assertSame('Test source with constraints', $field->label(), 'Incorrect label is used.');
+    $this->assertEquals('Test source with constraints', $field->label(), 'Incorrect label is used.');
     $this->assertSame('test_constraints_type', $field->getTargetBundle(), 'Field is not targeting correct bundle.');
   }
 
@@ -435,25 +435,25 @@
     $source = $manager->createInstance('test', []);
     $source->submitConfigurationForm($form, $form_state);
     $expected = ['test_config_value' => 'Somewhere over the rainbow.', 'source_field' => 'field_media_test_1'];
-    $this->assertSame($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
+    $this->assertEquals($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
 
     // Try to save a NULL value.
     $form_state->setValue('test_config_value', NULL);
     $source->submitConfigurationForm($form, $form_state);
     $expected['test_config_value'] = NULL;
-    $this->assertSame($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
+    $this->assertEquals($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
 
     // Make sure that the config keys are determined correctly even if the
     // existing value is NULL.
     $form_state->setValue('test_config_value', 'Somewhere over the rainbow.');
     $source->submitConfigurationForm($form, $form_state);
     $expected['test_config_value'] = 'Somewhere over the rainbow.';
-    $this->assertSame($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
+    $this->assertEquals($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
 
     // Make sure that a non-relevant value will be skipped.
     $form_state->setValue('not_relevant', 'Should not be saved in the plugin.');
     $source->submitConfigurationForm($form, $form_state);
-    $this->assertSame($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
+    $this->assertEquals($expected, $source->getConfiguration(), 'Submitted values were saved correctly.');
   }
 
   /**