diff --git a/core/modules/media/config/install/core.entity_form_display.media.file.default.yml b/core/modules/media/config/install/core.entity_form_display.media.file.default.yml
new file mode 100644
index 0000000..15de2ac
--- /dev/null
+++ b/core/modules/media/config/install/core.entity_form_display.media.file.default.yml
@@ -0,0 +1,44 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.media.file.field_media_file
+    - media.type.file
+  module:
+    - file
+id: media.file.default
+targetEntityType: media
+bundle: file
+mode: default
+content:
+  created:
+    type: datetime_timestamp
+    weight: 10
+    region: content
+    settings: {  }
+    third_party_settings: {  }
+  field_media_file:
+    settings:
+      progress_indicator: throbber
+    third_party_settings: {  }
+    type: file_generic
+    weight: 26
+    region: content
+  name:
+    type: string_textfield
+    weight: -5
+    region: content
+    settings:
+      size: 60
+      placeholder: ''
+    third_party_settings: {  }
+  uid:
+    type: entity_reference_autocomplete
+    weight: 5
+    settings:
+      match_operator: CONTAINS
+      size: 60
+      placeholder: ''
+    region: content
+    third_party_settings: {  }
+hidden: {  }
diff --git a/core/modules/media/config/install/core.entity_view_display.media.file.default.yml b/core/modules/media/config/install/core.entity_view_display.media.file.default.yml
new file mode 100644
index 0000000..697f117
--- /dev/null
+++ b/core/modules/media/config/install/core.entity_view_display.media.file.default.yml
@@ -0,0 +1,50 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.media.file.field_media_file
+    - image.style.thumbnail
+    - media.type.file
+  module:
+    - file
+    - image
+    - user
+id: media.file.default
+targetEntityType: media
+bundle: file
+mode: default
+content:
+  created:
+    label: hidden
+    type: timestamp
+    weight: 0
+    region: content
+    settings:
+      date_format: medium
+      custom_date_format: ''
+      timezone: ''
+    third_party_settings: {  }
+  field_media_file:
+    label: above
+    settings: {  }
+    third_party_settings: {  }
+    type: file_default
+    weight: 6
+    region: content
+  thumbnail:
+    type: image
+    weight: 5
+    label: hidden
+    settings:
+      image_style: thumbnail
+      image_link: ''
+    region: content
+    third_party_settings: {  }
+  uid:
+    label: hidden
+    type: author
+    weight: 0
+    region: content
+    settings: {  }
+    third_party_settings: {  }
+hidden: {  }
diff --git a/core/modules/media/config/install/field.field.media.file.field_media_file.yml b/core/modules/media/config/install/field.field.media.file.field_media_file.yml
new file mode 100644
index 0000000..70fcb6f
--- /dev/null
+++ b/core/modules/media/config/install/field.field.media.file.field_media_file.yml
@@ -0,0 +1,29 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.storage.media.field_media_file
+    - media.type.file
+  enforced:
+    module:
+      - media
+  module:
+    - file
+id: media.file.field_media_file
+field_name: field_media_file
+entity_type: media
+bundle: file
+label: File
+description: ''
+required: true
+translatable: true
+default_value: {  }
+default_value_callback: ''
+settings:
+  file_directory: '[date:custom:Y]-[date:custom:m]'
+  file_extensions: 'txt doc docx pdf'
+  max_filesize: ''
+  handler: 'default:file'
+  handler_settings: {  }
+  description_field: false
+field_type: file
diff --git a/core/modules/media/config/install/field.storage.media.field_media_file.yml b/core/modules/media/config/install/field.storage.media.field_media_file.yml
new file mode 100644
index 0000000..c251e11
--- /dev/null
+++ b/core/modules/media/config/install/field.storage.media.field_media_file.yml
@@ -0,0 +1,25 @@
+langcode: en
+status: true
+dependencies:
+  enforced:
+    module:
+      - media
+  module:
+    - file
+    - media
+id: media.field_media_file
+field_name: field_media_file
+entity_type: media
+type: file
+settings:
+  uri_scheme: public
+  target_type: file
+  display_field: false
+  display_default: false
+module: file
+locked: true
+cardinality: 1
+translatable: true
+indexes: { }
+persist_with_no_fields: false
+custom_storage: false
diff --git a/core/modules/media/config/install/media.type.file.yml b/core/modules/media/config/install/media.type.file.yml
new file mode 100644
index 0000000..af0abc2
--- /dev/null
+++ b/core/modules/media/config/install/media.type.file.yml
@@ -0,0 +1,12 @@
+langcode: en
+status: true
+dependencies: {  }
+id: file
+label: File
+description: "Use local files for reusable media."
+source: file
+queue_thumbnail_downloads: false
+new_revision: true
+source_configuration:
+  source_field: field_media_file
+field_map: { }
diff --git a/core/modules/media/config/schema/media.schema.yml b/core/modules/media/config/schema/media.schema.yml
index 14d40a9..69740f7 100644
--- a/core/modules/media/config/schema/media.schema.yml
+++ b/core/modules/media/config/schema/media.schema.yml
@@ -44,6 +44,10 @@ media.source.*:
   type: mapping
   label: 'Media source settings'
 
+media.source.file:
+  type: media.source.field_aware
+  label: '"File" media source configuration'
+
 media.source.field_aware:
   type: mapping
   mapping:
diff --git a/core/modules/media/images/icons/generic.png b/core/modules/media/images/icons/generic.png
index 2050a78..13090d8 100644
--- a/core/modules/media/images/icons/generic.png
+++ b/core/modules/media/images/icons/generic.png
@@ -1,3 +1,4 @@
-‰PNG
+‰PNG
 
-   IHDR   ´   ´    ¦Yî  fIDATxíÛå–â@@á}ÿ7¨JÂ0@Ywwwwww×íU9‡îfïýM’/®,’4hÐ A4hÐ Aƒ4hÐ Aƒ4hÐ AƒZ³,ï+ÕÐh]~ßúìË½µYXô–/6@G5$:ÿdƒôe‹D¯°Áú´T4z½Øó¦¤‡¶»E‚h;ª	¢mj`ôŽÉ	_“;ì—>®ž…™í,™ëE]¹™Õ%¿e®{Eè†HùÌ\—ó$Ð¥Š®øb®]šZtÇ77Ø‡Õ© E˜ës3´d·Ìõ K-ÍçæZ¬	òæj˜kUüè¦èLR1×šøÑg×oÙ±}û¶]×SBÿ(´>N-Ùúm®½wRA‹.´<J´§4hÐ Aƒk´z‹]¬?|ìÏŽ96ßîªD‡Ö-æéT|hYcž:tL÷ˆÍUkº´¬“ÿŽ^ýŽø—£Ç²y AÇ‰Î¥Ç4"´:S¹bå¯­X±j¡•­˜Ð…Ìµê‹uíÛ>=!sm4O§"DëÙ‡Ó=¸uc¾kÏÍwöÄÌ•ÓŽI‰-ê-BtøChÐ 5¯Nv«ˆÝze]{·JãCo6Og$>tqñå›.½ºÞ”Ù4Å3b\hÿ4hÐ [)¢ÛI£—¦ˆnƒ:ØóéÐ5é³å O·­,ë­s.$zˆÆzƒ]käèå6tõ‘£‹·6d35Z7~µ¡zÓ–¢]ÍKlÐ¾½<Ùôì!ãÏî Aƒ4hÐ Aƒ4hÐ Aƒ4hÐ Aƒ4èÀM+F—¦Eâ°    IEND®B`‚
\ No newline at end of file
+   IHDR   ´   ´    ¦Yî  dIDATxíÛå–Û0@á¾ÿÌØÞ (333333ã,ª[ŒçDÒöÞß‰ý™y‘$hÐ ý4hÐI4hÐ Aƒ4hÐ Aƒ4hÐ Ak–å¥­ËïÛ€}¹·6‹ÞòÅ†è¨†DçŸl˜¾lÑ€è6\Ÿ–ŠC¯·!{Þ’ôÐv·HmG5A´íQŒÞQ«øªí°_ú¸.4º"þ
+3ÛY3×‹20zBüåfÖü–¹îi ›"å3s]Î“@—*ºâ‹¹vi"hÑßÜß>¬N-zÄ\Ÿ[© %»e®Y*hi=7×bM`—7[Ó\«âG·D§“	s­‰}vý–Û·oÛu=%ôRAëãÑ’­ßæÚ{'´è|Ë£D{*44hÐ AƒVoñ¡‹õ‡ýÙ‘#ÇæÚ]•èÐºÅ<Š-kÌÓA‡Žé±µjM–uóßÑË£ßÿ²÷X–Ê./~4hÐ¹ô™F„Vg*W¬üµ+VÍ·²ºÙV}±ž}Û§ñ +2ÛFót*B´ž}8Õƒ[7æºvñÜ\gOLŸ9í¨I|hQoñ¡#ØåZój­WEŒèö+ëÙ»Uz³y:#ñ¡‹‹/ßôèÕõ–Ì¤‰#DûûïÐ AƒÝNÝI½4Et4hÐÁîOÇ€®Ë€- }ºÓükeÙøkÝs!Ñ#´ÐÑ 7ØÈµÇŽ^n#×;ºxk#ö8“q£uãW©7#ÚÕºôÁ†íÛË“­@Ÿ`»ƒ4hÐ Aƒ4hÐ Aƒ4hÐ Aƒ4hÐ 7	+F—¦ž*é‰    IEND®B`‚
\ No newline at end of file
diff --git a/core/modules/media/media.info.yml b/core/modules/media/media.info.yml
index 07167d6..e6e6da2 100644
--- a/core/modules/media/media.info.yml
+++ b/core/modules/media/media.info.yml
@@ -5,6 +5,5 @@ package: Core (Experimental)
 version: VERSION
 core: 8.x
 dependencies:
-  - file
   - image
   - user
diff --git a/core/modules/media/media.install b/core/modules/media/media.install
index 87aeb36..8231164 100644
--- a/core/modules/media/media.install
+++ b/core/modules/media/media.install
@@ -28,6 +28,15 @@ function media_install() {
 }
 
 /**
+ * Implements hook_uninstall().
+ *
+ * @TODO Remove when https://www.drupal.org/node/2884202 is fixed.
+ */
+function media_uninstall() {
+  \Drupal::moduleHandler()->invoke('field', 'cron');
+}
+
+/**
  * Implements hook_requirements().
  */
 function media_requirements($phase) {
diff --git a/core/modules/media/src/Plugin/media/Source/File.php b/core/modules/media/src/Plugin/media/Source/File.php
new file mode 100644
index 0000000..b6ad979
--- /dev/null
+++ b/core/modules/media/src/Plugin/media/Source/File.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace Drupal\media\Plugin\media\Source;
+
+use Drupal\file\FileInterface;
+use Drupal\media\MediaInterface;
+use Drupal\media\MediaTypeInterface;
+use Drupal\media\MediaSourceBase;
+
+/**
+ * File entity media source.
+ *
+ * @see \Drupal\file\FileInterface
+ *
+ * @MediaSource(
+ *   id = "file",
+ *   label = @Translation("File"),
+ *   description = @Translation("Use local files for reusable media."),
+ *   allowed_field_types = {"file"},
+ *   default_thumbnail_filename = "generic.png"
+ * )
+ */
+class File extends MediaSourceBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMetadataAttributes() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMetadata(MediaInterface $media, $attribute_name) {
+    /** @var \Drupal\file\FileInterface $file */
+    $file = $media->get($this->configuration['source_field'])->entity;
+    // If the source field is not required, it may be empty.
+    if (!$file) {
+      return parent::getMetadata($media, $attribute_name);
+    }
+    switch ($attribute_name) {
+      case 'default_name':
+        return $file->getFilename();
+
+      case 'thumbnail_uri':
+        return $this->getThumbnail($file) ?: parent::getMetadata($media, $attribute_name);
+
+      default:
+        return parent::getMetadata($media, $attribute_name);
+    }
+  }
+
+  /**
+   * Gets the thumbnail image URI based on a file entity.
+   *
+   * @param \Drupal\file\FileInterface $file
+   *   A file entity.
+   *
+   * @return string
+   *   File URI of the thumbnail image or NULL if there is no specific icon.
+   */
+  protected function getThumbnail(FileInterface $file) {
+    $icon_base = $this->configFactory->get('media.settings')->get('icon_base_uri');
+
+    // We try to automatically use the most specific icon present in the
+    // $icon_base directory, based on the MIME type. For instance, if an
+    // icon file named "pdf.png" is present, it will be used if the file
+    // matches this MIME type.
+    $mimetype = $file->getMimeType();
+    $mimetype = explode('/', $mimetype);
+
+    $icon_names = [
+      $mimetype[0] . '--' . $mimetype[1],
+      $mimetype[1],
+      $mimetype[0],
+    ];
+    foreach ($icon_names as $icon_name) {
+      $thumbnail = $icon_base . '/' . $icon_name . '.png';
+      if (is_file($thumbnail)) {
+        return $thumbnail;
+      }
+    }
+
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createSourceField(MediaTypeInterface $type) {
+    return parent::createSourceField($type)->set('settings', ['file_extensions' => 'txt doc docx pdf']);
+  }
+
+}
diff --git a/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php b/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
index 883f27e..e37b850 100644
--- a/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
+++ b/core/modules/media/tests/src/Functional/MediaUiFunctionalTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\media\Functional;
 
 use Drupal\media\Entity\Media;
+use Drupal\media\Entity\MediaType;
 
 /**
  * Ensures that media UI works correctly.
@@ -28,6 +29,10 @@ protected function setUp() {
     parent::setUp();
     $this->drupalPlaceBlock('local_actions_block');
     $this->drupalPlaceBlock('local_tasks_block');
+
+    // We need to test without any default configuration in place.
+    // @TODO: Remove this when https://www.drupal.org/node/2883813 lands.
+    MediaType::load('file')->delete();
   }
 
   /**
diff --git a/core/modules/media/tests/src/FunctionalJavascript/MediaSourceFileTest.php b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceFileTest.php
new file mode 100644
index 0000000..8c80b83
--- /dev/null
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceFileTest.php
@@ -0,0 +1,71 @@
+<?php
+
+namespace Drupal\Tests\media\FunctionalJavascript;
+
+use Drupal\media\Entity\Media;
+use Drupal\media\Entity\MediaType;
+
+/**
+ * Tests the file media source.
+ *
+ * @group media
+ */
+class MediaSourceFileTest extends MediaSourceTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // We need to test without any default configuration in place.
+    // @TODO: Remove this as part of https://www.drupal.org/node/2883813.
+    MediaType::load('file')->delete();
+  }
+
+  /**
+   * Tests the file media source.
+   */
+  public function testMediaFileSource() {
+    $media_type_id = 'test_media_file_type';
+    $source_field_id = 'field_media_file';
+
+    $session = $this->getSession();
+    $page = $session->getPage();
+    $assert_session = $this->assertSession();
+
+    $this->doTestCreateMediaType($media_type_id, 'file');
+
+    // Hide the name field widget to test default name generation.
+    $this->hideMediaTypeFieldWidget('name', $media_type_id);
+
+    $test_filename = $this->randomMachineName() . '.txt';
+    $test_filepath = 'public://' . $test_filename;
+    file_put_contents($test_filepath, $this->randomMachineName());
+
+    // Create a media item.
+    $this->drupalGet("media/add/{$media_type_id}");
+    $page->attachFileToField("files[{$source_field_id}_0]", \Drupal::service('file_system')->realpath($test_filepath));
+    $assert_session->assertWaitOnAjaxRequest();
+    $page->pressButton('Save and publish');
+
+    $assert_session->addressEquals('media/1');
+
+    // Make sure the thumbnail is displayed.
+    $assert_session->elementAttributeContains('css', '.image-style-thumbnail', 'src', 'generic.png');
+
+    // Load the media and check if the label was properly populated.
+    $media = Media::load(1);
+    $this->assertEquals($test_filename, $media->label());
+
+    // Test the MIME type icon.
+    $icon_base = \Drupal::config('media.settings')->get('icon_base_uri');
+    file_unmanaged_copy($icon_base . '/generic.png', $icon_base . '/text--plain.png');
+    $this->drupalGet("media/add/{$media_type_id}");
+    $page->attachFileToField("files[{$source_field_id}_0]", \Drupal::service('file_system')->realpath($test_filepath));
+    $assert_session->assertWaitOnAjaxRequest();
+    $page->pressButton('Save and publish');
+    $assert_session->elementAttributeContains('css', '.image-style-thumbnail', 'src', 'text--plain.png');
+  }
+
+}
diff --git a/core/modules/media/tests/src/FunctionalJavascript/MediaSourceTestBase.php b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceTestBase.php
new file mode 100644
index 0000000..5af6d5c
--- /dev/null
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaSourceTestBase.php
@@ -0,0 +1,125 @@
+<?php
+
+namespace Drupal\Tests\media\FunctionalJavascript;
+
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\media\Entity\MediaType;
+
+/**
+ * Base class for media source tests.
+ */
+abstract class MediaSourceTestBase extends MediaJavascriptTestBase {
+
+  /**
+   * Creates storage and field instance, attached to a given media type.
+   *
+   * @param string $field_name
+   *   The field name.
+   * @param string $field_type
+   *   The field type.
+   * @param string $media_type_id
+   *   The media type config entity ID.
+   */
+  protected function createMediaTypeField($field_name, $field_type, $media_type_id) {
+    $storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'media',
+      'type' => $field_type,
+    ]);
+    $storage->save();
+
+    FieldConfig::create([
+      'field_storage' => $storage,
+      'bundle' => $media_type_id,
+    ])->save();
+
+    // Make the field widget visible in the form display.
+    $component = \Drupal::service('plugin.manager.field.widget')
+      ->prepareConfiguration($field_type, []);
+    /** @var \Drupal\Core\Entity\Display\EntityFormDisplayInterface $entity_form_display */
+    $entity_form_display = entity_get_form_display('media', $media_type_id, 'default');
+    $entity_form_display->setComponent($field_name, $component)
+      ->save();
+  }
+
+  /**
+   * Create a set of fields in a media type.
+   *
+   * @param array $fields
+   *   An associative array where keys are field names and values field types.
+   * @param string $media_type_id
+   *   The media type config entity ID.
+   */
+  protected function createMediaTypeFields(array $fields, $media_type_id) {
+    foreach ($fields as $field_name => $field_type) {
+      $this->createMediaTypeField($field_name, $field_type, $media_type_id);
+    }
+  }
+
+  /**
+   * Hides a widget in the default form display config.
+   *
+   * @param string $field_name
+   *   The field name.
+   * @param string $media_type_id
+   *   The media type config entity ID.
+   */
+  protected function hideMediaTypeFieldWidget($field_name, $media_type_id) {
+    /** @var \Drupal\Core\Entity\Display\EntityFormDisplayInterface $entity_form_display */
+    $entity_form_display = entity_get_form_display('media', $media_type_id, 'default');
+    if ($entity_form_display->getComponent($field_name)) {
+      $entity_form_display->removeComponent($field_name)->save();
+    }
+  }
+
+  /**
+   * Test generic media type creation.
+   *
+   * @param string $media_type_id
+   *   The media type config entity ID.
+   * @param string $source_id
+   *   The media source ID.
+   * @param array $provided_fields
+   *   (optional) An array of field machine names this type provides.
+   *
+   * @return \Drupal\media\MediaTypeInterface
+   *   The created media type.
+   */
+  public function doTestCreateMediaType($media_type_id, $source_id, array $provided_fields = []) {
+    $session = $this->getSession();
+    $page = $session->getPage();
+    $assert_session = $this->assertSession();
+
+    $this->drupalGet('admin/structure/media/add');
+    $page->fillField('label', $media_type_id);
+    $this->getSession()
+      ->wait(5000, "jQuery('.machine-name-value').text() === '{$media_type_id}'");
+
+    // Make sure the source is available.
+    $assert_session->fieldExists('Media source');
+    $assert_session->optionExists('Media source', $source_id);
+    $page->selectFieldOption('Media source', $source_id);
+    $assert_session->assertWaitOnAjaxRequest();
+
+    // Make sure the provided fields are visible on the form.
+    foreach ($provided_fields as $provided_field) {
+      $assert_session->selectExists("field_map[{$provided_field}]");
+    }
+
+    // Save the form to create the type.
+    $page->pressButton('Save');
+    $assert_session->statusCodeEquals(200);
+    $assert_session->pageTextContains('The media type ' . $media_type_id . ' has been added.');
+    $this->drupalGet('admin/structure/media');
+    $assert_session->pageTextContains($media_type_id);
+
+    // Bundle definitions are statically cached in the context of the test, we
+    // need to make sure we have updated information before proceeding with the
+    // actions on the UI.
+    \Drupal::service('entity_type.bundle.info')->clearCachedBundles();
+
+    return MediaType::load($media_type_id);
+  }
+
+}
diff --git a/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
index fb98d90..bb49fef 100644
--- a/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
+++ b/core/modules/media/tests/src/FunctionalJavascript/MediaUiJavascriptTest.php
@@ -38,6 +38,10 @@ protected function setUp() {
     parent::setUp();
     $this->drupalPlaceBlock('local_actions_block');
     $this->drupalPlaceBlock('local_tasks_block');
+
+    // We need to test without any default configuration in place.
+    // @TODO: Remove this as part of https://www.drupal.org/node/2883813.
+    MediaType::load('file')->delete();
   }
 
   /**
diff --git a/core/modules/media/tests/src/Kernel/MediaKernelTestBase.php b/core/modules/media/tests/src/Kernel/MediaKernelTestBase.php
index 0daec87..5d75bed 100644
--- a/core/modules/media/tests/src/Kernel/MediaKernelTestBase.php
+++ b/core/modules/media/tests/src/Kernel/MediaKernelTestBase.php
@@ -2,8 +2,12 @@
 
 namespace Drupal\Tests\media\Kernel;
 
+use Drupal\file\Entity\File;
 use Drupal\KernelTests\KernelTestBase;
+use Drupal\media\Entity\Media;
 use Drupal\media\Entity\MediaType;
+use Drupal\media\MediaTypeInterface;
+use org\bovigo\vfs\vfsStream;
 
 /**
  * Base class for Media kernel tests.
@@ -88,4 +92,42 @@ protected function createMediaType($media_source_name) {
     return $media_type;
   }
 
+  /**
+   * Helper to generate media entity.
+   *
+   * @param string $filename
+   *   String filename with extension.
+   * @param \Drupal\media\MediaTypeInterface $media_type
+   *   The the media type.
+   *
+   * @return \Drupal\media\Entity\Media
+   *   A media entity.
+   */
+  protected function generateMedia($filename, MediaTypeInterface $media_type) {
+    vfsStream::setup('drupal_root');
+    vfsStream::create([
+      'sites' => [
+        'default' => [
+          'files' => [
+            $filename => str_repeat('a', 3000),
+          ],
+        ],
+      ],
+    ]);
+
+    $file = File::create([
+      'uri' => 'vfs://drupal_root/sites/default/files/' . $filename,
+    ]);
+    $file->setPermanent();
+    $file->save();
+
+    return Media::create([
+      'bundle' => $media_type->id(),
+      'name' => 'Mr. Jones',
+      'field_media_file' => [
+        'target_id' => $file->id(),
+      ],
+    ]);
+  }
+
 }
diff --git a/core/modules/media/tests/src/Kernel/MediaSourceFileTest.php b/core/modules/media/tests/src/Kernel/MediaSourceFileTest.php
new file mode 100644
index 0000000..9ad6916
--- /dev/null
+++ b/core/modules/media/tests/src/Kernel/MediaSourceFileTest.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Drupal\Tests\media\Kernel;
+
+use Drupal\media\Entity\MediaType;
+
+/**
+ * Tests the file media source.
+ *
+ * @group media
+ */
+class MediaSourceFileTest extends MediaKernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // We need to test without any default configuration in place.
+    // @TODO: Remove this as part of https://www.drupal.org/node/2883813.
+    MediaType::load('file')->delete();
+  }
+
+  /**
+   * Tests the file extension constraint.
+   */
+  public function testFileExtensionConstraint() {
+    $mediaType = $this->createMediaType('file');
+    // Create a random file that should fail.
+    $media = $this->generateMedia('test.patch', $mediaType);
+    $result = $media->validate();
+    $this->assertCount(1, $result);
+    $this->assertEquals('field_media_file.0', $result->get(0)->getPropertyPath());
+    $this->assertContains('Only files with the following extensions are allowed:', (string) $result->get(0)->getMessage());
+
+    // Create a random file that should pass.
+    $media = $this->generateMedia('test.txt', $mediaType);
+    $result = $media->validate();
+    $this->assertCount(0, $result);
+  }
+
+}