Issue #3154909 by jungle, adityasingh, nitesh624, mohrerao, rajandro, sanjayk,...

        }

      }

      else {

        // Database connection failed for some other reason than the database

        // not existing.

        // Database connection failed for some other reason than a non-existent

        // database.

        $this->fail(t('Failed to connect to your database server. The server reports the following message: %error.<ul><li>Is the database server running?</li><li>Does the database exist or does the database user have sufficient privileges to create the database?</li><li>Have you entered the correct database name?</li><li>Have you entered the correct username and password?</li><li>Have you entered the correct database hostname and port number?</li></ul>', ['%error' => $e->getMessage()]));

        return FALSE;

      }

        }

      }

      else {

        // Database connection failed for some other reason than the database

        // not existing.

        // Database connection failed for some other reason than a non-existent

        // database.

        $this->fail(t('Failed to connect to your database server. The server reports the following message: %error.<ul><li>Is the database server running?</li><li>Does the database exist, and have you entered the correct database name?</li><li>Have you entered the correct username and password?</li><li>Have you entered the correct database hostname and port number?</li></ul>', ['%error' => $e->getMessage()]));

        return FALSE;

      }

        }

      }

      else {

        // Database connection failed for some other reason than the database

        // not existing.

        // Database connection failed for some other reason than a non-existent

        // database.

        $this->fail(t('Failed to connect to database. The database engine reports the following message: %error.<ul><li>Does the database file exist?</li><li>Does web server have permission to write to the database file?</li>Does the web server have permission to write to the directory the database file should be created in?</li></ul>', ['%error' => $e->getMessage()]));

        return FALSE;

      }

   *   The property value.

   *

   * @throws \InvalidArgumentException

   *   If a not existing property is accessed.

   *   If a non-existent property is accessed.

   */

  public function __get($property_name);

   *   passed instead of a plain value.

   *

   * @throws \InvalidArgumentException

   *   If a not existing property is set.

   *   If a non-existent property is set.

   */

  public function __set($property_name, $value);

    $this->drupalGet('book/export/foobar/' . $this->book->id());

    $this->assertSession()->statusCodeEquals(404);

    // Make sure we get a 404 on a not existing book node.

    // Make sure we get a 404 on a non-existent book node.

    $this->drupalGet('book/export/html/123');

    $this->assertSession()->statusCodeEquals(404);