diff --git a/core/modules/update/src/Form/UpdateManagerInstall.php b/core/modules/update/src/Form/UpdateManagerInstall.php
index 5524f9e..fcd8de5 100644
--- a/core/modules/update/src/Form/UpdateManagerInstall.php
+++ b/core/modules/update/src/Form/UpdateManagerInstall.php
@@ -219,12 +219,17 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
       'local_url' => $project_real_location,
     );
 
+    // This process is inherently difficult to test therefore use a state flag.
+    $test_authorize = FALSE;
+    if (drupal_valid_test_ua()) {
+      $test_authorize = \Drupal::state()->get('test_uploaders_via_prompt', FALSE);
+    }
     // If the owner of the directory we extracted is the same as the owner of
     // our configuration directory (e.g. sites/default) where we're trying to
     // install the code, there's no need to prompt for FTP/SSH credentials.
     // Instead, we instantiate a Drupal\Core\FileTransfer\Local and invoke
     // update_authorize_run_install() directly.
-    if (fileowner($project_real_location) == fileowner($this->sitePath)) {
+    if (fileowner($project_real_location) == fileowner($this->sitePath) && !$test_authorize) {
       $this->moduleHandler->loadInclude('update', 'inc', 'update.authorize');
       $filetransfer = new Local($this->root);
       $response = call_user_func_array('update_authorize_run_install', array_merge(array($filetransfer), $arguments));
diff --git a/core/modules/update/src/Tests/UpdateViaAuthorizeTest.php b/core/modules/update/src/Tests/UpdateViaAuthorizeTest.php
new file mode 100644
index 0000000..7f7fe6e
--- /dev/null
+++ b/core/modules/update/src/Tests/UpdateViaAuthorizeTest.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Drupal\update\Tests;
+
+/**
+ * Tests the Update Manager module upload via authorize.php functionality.
+ *
+ * @group update
+ */
+class UpdateViaAuthorizeTest extends UpdateTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('update', 'update_test');
+
+  protected function setUp() {
+    parent::setUp();
+    $admin_user = $this->drupalCreateUser(array('administer modules', 'administer software updates', 'administer site configuration'));
+    $this->drupalLogin($admin_user);
+  }
+
+  /**
+   * Tests the Update Manager module upload via authorize.php functionality.
+   */
+  public function testViaAuthorize() {
+    // Ensure the that we can select which file transfer backend to use.
+    \Drupal::state()->set('test_uploaders_via_prompt', TRUE);
+
+    $edit = [
+      'project_url' => 'https://ftp.drupal.org/files/projects/config_inspector-8.x-1.0-beta1.tar.gz',
+    ];
+    $this->drupalPostForm('http://drupal8alt.dev/admin/modules/install', $edit, t('Install'));
+    $edit = [
+      'connection_settings[authorize_filetransfer_default]' => 'system_test',
+      'connection_settings[system_test][update_test_username]' => $this->randomMachineName(),
+    ];
+    $this->drupalPostForm(NULL, $edit, t('Continue'));
+    $this->assertText(t('Installation was completed successfully.'));
+  }
+
+}
diff --git a/core/modules/update/tests/modules/update_test/src/MockFileTransfer.php b/core/modules/update/tests/modules/update_test/src/MockFileTransfer.php
index 9e40b65..3873d6b 100644
--- a/core/modules/update/tests/modules/update_test/src/MockFileTransfer.php
+++ b/core/modules/update/tests/modules/update_test/src/MockFileTransfer.php
@@ -2,10 +2,17 @@
 
 namespace Drupal\update_test;
 
+use Drupal\Core\FileTransfer\Local;
+
 /**
  * Mocks a FileTransfer object to test the settings form functionality.
+ *
+ * This class extends \Drupal\Core\FileTransfer\Local to make module install
+ * testing via authorize.php possible.
+ *
+ * @see \Drupal\update\Tests\UpdateViaAuthorizeTest
  */
-class MockFileTransfer {
+class MockFileTransfer extends Local {
 
   /**
    * Returns a Drupal\update_test\MockFileTransfer object.
@@ -13,8 +20,8 @@ class MockFileTransfer {
    * @return \Drupal\update_test\MockFileTransfer
    *   A new Drupal\update_test\MockFileTransfer object.
    */
-  public static function factory() {
-    return new FileTransfer();
+  public static function factory($jail, $settings) {
+    return new static($jail);
   }
 
   /**