Function check

specs/Modal.spec.js:677–677

(tobe)

      Modal.setAppElement(appElement);

      const check = (tobe) => appElement.getAttribute("aria-hidden").should.be.eql(tobe);

      const props = { isOpen: true, ariaHideApp: true, id: "test-3-modal-1" };
      withModal(props, null, () => {