public function test_with_invalid_nonce() {

    wp_set_current_user( self::$admin_id );

    // Set up the $_POST request.
    $_POST = array(
      'action' => 'heartbeat',
      '_nonce' => wp_create_nonce( 'heartbeat-nonce' ),
      'data'   => array(
        'wp_autosave' => array(
          'post_id'  => self::$post_id,
          '_wpnonce' => substr( md5( uniqid() ), 0, 10 ),
        ),
      ),
    );

    // Make the request.
    try {
      $this->_handleAjax( 'heartbeat' );
    } catch ( WPAjaxDieContinueException $e ) {
      unset( $e );
    }

    $response = json_decode( $this->_last_response, true );

    $this->assertNotEmpty( $response['wp_autosave'] );
    $this->assertFalse( $response['wp_autosave']['success'] );
  }