backup globals whitelist for PHPUnit test case

testcase.php

	/**
	 * A list of global variables to back up.
	 *
	 * @since 2.0.0
	 *
	 * @var string|string[]
	 */
	protected $backup_globals;

	/**
	 * Backed-up globals.
	 *
	 * @since 2.0.0
	 *
	 * @var array
	 */
	protected $globals_backup = array();

	public function setUp() {

		parent::setUp();

	
		if ( ! empty( $this->backup_globals ) ) {
			foreach ( (array) $this->backup_globals as $global ) {
				if ( isset( $GLOBALS[ $global ] ) ) {
					$this->globals_backup[ $global ] = $GLOBALS[ $global ];
				}
			}
		}
	}

	public function tearDown() {

		if ( ! empty( $this->backup_globals ) ) {
			foreach ( (array) $this->backup_globals as $global ) {
				if ( isset( $this->globals_backup[ $global ] ) ) {
					$GLOBALS[ $global ] = $this->globals_backup[ $global ];
				} else {
					unset( $GLOBALS[ $global ] );
				}
			}
		}

		parent::tearDown();
	}