Issue #2413695 by joelpittet: Modules getting installed in the theme directory if they don't have a *.module file

core/lib/Drupal/Core/Updater/Module.php

@@ -51,10 +51,9 @@ class Module extends Updater implements UpdaterInterface {
    * Implements Drupal\Core\Updater\UpdaterInterface::canUpdateDirectory().
    */
   public static function canUpdateDirectory($directory) {
-    if (file_scan_directory($directory, '/.*\.module$/')) {
-      return TRUE;
-    }
-    return FALSE;
+    $info = static::getExtensionInfo($directory);
+
+    return (isset($info['type']) && $info['type'] == 'module');
   }
 
   /**

core/lib/Drupal/Core/Updater/Theme.php

@@ -51,11 +51,9 @@ class Theme extends Updater implements UpdaterInterface {
    * Implements Drupal\Core\Updater\UpdaterInterface::canUpdateDirectory().
    */
   static function canUpdateDirectory($directory) {
-    // This is a lousy test, but don't know how else to confirm it is a theme.
-    if (file_scan_directory($directory, '/.*\.module$/')) {
-      return FALSE;
-    }
-    return TRUE;
+    $info = static::getExtensionInfo($directory);
+
+    return (isset($info['type']) && $info['type'] == 'theme');
   }
 
   /**

core/lib/Drupal/Core/Updater/Updater.php

@@ -111,6 +111,28 @@ class Updater {
     return $info_file->uri;
   }
 
+  /**
+   * Get Extension information from directory.
+   *
+   * @param string $directory
+   *   Directory to search in.
+   *
+   * @return array
+   *   Extension info.
+   *
+   * @throws \Drupal\Core\Updater\UpdaterException
+   *   If the info parser does not provide any info.
+   */
+  protected static function getExtensionInfo($directory) {
+    $info_file = static::findInfoFile($directory);
+    $info = \Drupal::service('info_parser')->parse($info_file);
+    if (empty($info)) {
+      throw new UpdaterException(t('Unable to parse info file: %info_file.', ['%info_file' => $info_file]));
+    }
+
+    return $info;
+  }
+
   /**
    * Gets the name of the project directory (basename).
    *

core/lib/Drupal/Core/Updater/UpdaterInterface.php

@@ -45,8 +45,6 @@ interface UpdaterInterface {
   /**
    * Determines if the Updater can handle the project provided in $directory.
    *
-   * @todo Provide something more rational here, like a project spec file.
-   *
    * @param string $directory
    *
    * @return bool

core/modules/update/src/Tests/UpdateUploadTest.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\update\Tests;
 
+use Drupal\Core\Updater\Updater;
 use Drupal\Core\Url;
 
 /**
@@ -111,4 +112,16 @@ class UpdateUploadTest extends UpdateTestBase {
     $this->drupalGet('admin/update/ready');
     $this->assertNoText(t('There is a security update available for your version of Drupal.'));
   }
+
+  /**
+   * Tests only an *.info.yml file are detected without supporting files.
+   */
+  public function testUpdateDirectory() {
+    $type = Updater::getUpdaterFromDirectory(\Drupal::root() . '/core/modules/update/tests/modules/aaa_update_test');
+    $this->assertEqual($type, 'Drupal\\Core\\Updater\\Module', 'Detected a Module');
+
+    $type = Updater::getUpdaterFromDirectory(\Drupal::root() . '/core/modules/update/tests/themes/update_test_basetheme');
+    $this->assertEqual($type, 'Drupal\\Core\\Updater\\Theme', 'Detected a Theme.');
+  }
+
 }