Issue #3092658 by gilesmc, longwave: Remove all @deprecated code in the Basic Auth module

core/modules/basic_auth/src/Tests/BasicAuthTestTrait.php

-<?php
-
-namespace Drupal\basic_auth\Tests;
-
-@trigger_error(__NAMESPACE__ . '\BasicAuthTestTrait is deprecated in Drupal 8.3.0 and will be removed before Drupal 9.0.0. Use \Drupal\Tests\basic_auth\Traits\BasicAuthTestTrait instead. See https://www.drupal.org/node/2862800.', E_USER_DEPRECATED);
-
-/**
- * Provides common functionality for Basic Authentication test classes.
- *
- * @deprecated in drupal:8.3.0 and is removed from drupal:9.0.0.
- *   Use \Drupal\Tests\basic_auth\Traits\BasicAuthTestTrait instead.
- *
- * @see https://www.drupal.org/node/2862800
- */
-trait BasicAuthTestTrait {
-
-  /**
-   * Retrieves a Drupal path or an absolute path using basic authentication.
-   *
-   * @param \Drupal\Core\Url|string $path
-   *   Drupal path or URL to load into the internal browser.
-   * @param string $username
-   *   The username to use for basic authentication.
-   * @param string $password
-   *   The password to use for basic authentication.
-   * @param array $options
-   *   (optional) Options to be forwarded to the url generator.
-   *
-   * @return string
-   *   The retrieved HTML string, also available as $this->getRawContent().
-   */
-  protected function basicAuthGet($path, $username, $password, array $options = []) {
-    return $this->drupalGet($path, $options, $this->getBasicAuthHeaders($username, $password));
-  }
-
-  /**
-   * Executes a form submission using basic authentication.
-   *
-   * @param string $path
-   *   Location of the post form.
-   * @param array $edit
-   *   Field data in an associative array.
-   * @param string $submit
-   *   Value of the submit button whose click is to be emulated.
-   * @param string $username
-   *   The username to use for basic authentication.
-   * @param string $password
-   *   The password to use for basic authentication.
-   * @param array $options
-   *   Options to be forwarded to the url generator.
-   * @param string $form_html_id
-   *   (optional) HTML ID of the form to be submitted.
-   * @param string $extra_post
-   *   (optional) A string of additional data to append to the POST submission.
-   *
-   * @return string
-   *   The retrieved HTML string.
-   *
-   * @see \Drupal\simpletest\WebTestBase::drupalPostForm()
-   */
-  protected function basicAuthPostForm($path, $edit, $submit, $username, $password, array $options = [], $form_html_id = NULL, $extra_post = NULL) {
-    return $this->drupalPostForm($path, $edit, $submit, $options, $this->getBasicAuthHeaders($username, $password), $form_html_id, $extra_post);
-  }
-
-  /**
-   * Returns HTTP headers that can be used for basic authentication in Curl.
-   *
-   * @param string $username
-   *   The username to use for basic authentication.
-   * @param string $password
-   *   The password to use for basic authentication.
-   *
-   * @return array
-   *   An array of raw request headers as used by curl_setopt().
-   */
-  protected function getBasicAuthHeaders($username, $password) {
-    // Set up Curl to use basic authentication with the test user's credentials.
-    return ['Authorization: Basic ' . base64_encode("$username:$password")];
-  }
-
-}