Update Composer, update everything

web/core/tests/Drupal/TestSite/TestSetupInterface.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Drupal\TestSite;
+
+/**
+ * Allows setting up an environment as part of a test site install.
+ *
+ * @see \Drupal\TestSite\Commands\TestSiteInstallCommand
+ */
+interface TestSetupInterface {
+
+  /**
+   * Run the code to setup the test environment.
+   *
+   * You have access to any API provided by any installed module. For example,
+   * to install modules use:
+   * @code
+   * \Drupal::service('module_installer')->install(['my_module'])
+   * @endcode
+   *
+   * Check out TestSiteInstallTestScript for an example.
+   *
+   * @see \Drupal\TestSite\TestSiteInstallTestScript
+   */
+  public function setup();
+
+}