diff --git a/core/tests/Drupal/KernelTests/Core/File/MimeTypeTest.php b/core/tests/Drupal/KernelTests/Core/File/MimeTypeTest.php
index 9979d9c..9657a7b 100644
--- a/core/tests/Drupal/KernelTests/Core/File/MimeTypeTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/MimeTypeTest.php
@@ -51,6 +51,32 @@ public function testFileMimeTypeDetection() {
       $this->assertIdentical($output, $expected, format_string('Mimetype (using default mappings) for %input is %output (expected: %expected).', array('%input' => $input, '%output' => $output, '%expected' => $expected)));
     }
 
+    // Now test that MIME types added via alter hook are present in the list
+    // returned by MimeTypeMapper::getMimeTypes.
+    $mime_type_mapper = $this->container->get('file.mime_type.mapper');
+    $test_case = [
+      'madeup/file_test_1' => ['file_test_1'],
+      'madeup/file_test_2' => ['file_test_2', 'file_test_3'],
+      'madeup/doc' => ['doc'],
+    ];
+    $expected = array_keys($test_case);
+    $this->assertIdentical($expected, array_intersect($expected, $mime_type_mapper->getMimeTypes()));
+
+    // Now test the extensions returned by the MIME type mapper given
+    // a MIME type.
+    foreach ($test_case as $input => $expected) {
+      $extensions = $mime_type_mapper->getExtensionsForMimeType($input);
+      $this->assertIdentical($expected, $extensions);
+    }
+
+    // Now test mapping removals.
+    $this->assertFalse($mime_type_mapper->removeMimeType('ready/made'), 'Unexisting MIME type not removed.');
+    $this->assertTrue($mime_type_mapper->removeMimeType('madeup/file_test_1'), 'Existing MIME type removed.');
+    $this->assertIdentical($mime_type_mapper->getExtensionsForMimeType('madeup/file_test_1'), [], 'No extensions mapped for removed MIME type.');
+    $this->assertFalse($mime_type_mapper->removeMapping('readymade'), 'Unexisting extension not removed.');
+    $this->assertTrue($mime_type_mapper->removeMapping('file_test_3'), 'Existing extension removed.');
+    $this->assertIdentical($mime_type_mapper->getExtensionsForMimeType('madeup/file_test_2'), ['file_test_2'], 'Expected extensions mapped to MIME type after extension removal.');
+
     // Now test the extension gusser by passing in a custom mapping.
     $mapping = array(
       'mimetypes' => array(
@@ -85,37 +111,6 @@ public function testFileMimeTypeDetection() {
       $output = $extension_guesser->guess($input);
       $this->assertIdentical($output, $expected, format_string('Mimetype (using passed-in mappings) for %input is %output (expected: %expected).', array('%input' => $input, '%output' => $output, '%expected' => $expected)));
     }
-
-    // Now test that MIME types added via alter hook or directly via
-    // MimeTypeMapper::addMapping are present in the list returned by
-    // MimeTypeMapper::getMimeTypes.
-    $mime_type_mapper = $this->container->get('file.mime_type.mapper');
-    $test_case = [
-      'bar/foo' => ['jar'],
-      'fox/trot' => ['jpg'],
-      'image/jpeg' => ['jpe', 'jpeg'],
-      'madeup/file_test_1' => ['file_test_1'],
-      'madeup/file_test_2' => ['file_test_2', 'file_test_3'],
-      'madeup/doc' => ['doc'],
-      'drupal/info' => ['info.yml'],
-    ];
-    $expected = array_keys($test_case);
-    $this->assertIdentical($expected, array_intersect($expected, $mime_type_mapper->getMimeTypes()));
-
-    // Now test the extensions returned by the MIME type mapper given
-    // a MIME type.
-    foreach ($test_case as $input => $expected) {
-      $extensions = $mime_type_mapper->getExtensionsForMimeType($input);
-      $this->assertIdentical($expected, $extensions);
-    }
-
-    // Now test mapping removals.
-    $this->assertFalse($mime_type_mapper->removeMimeType('ready/made'), 'Unexisting MIME type not removed.');
-    $this->assertTrue($mime_type_mapper->removeMimeType('madeup/file_test_1'), 'Existing MIME type removed.');
-    $this->assertIdentical($mime_type_mapper->getExtensionsForMimeType('madeup/file_test_1'), [], 'No extensions mapped for removed MIME type.');
-    $this->assertFalse($mime_type_mapper->removeMapping('readymade'), 'Unexisting extension not removed.');
-    $this->assertTrue($mime_type_mapper->removeMapping('file_test_3'), 'Existing extension removed.');
-    $this->assertIdentical($mime_type_mapper->getExtensionsForMimeType('madeup/file_test_2'), ['file_test_2'], 'Expected extensions mapped to MIME type after extension removal.');
   }
 
 }