@material-ui/core/es/test-utils/createMount.js

import _extends from "@babel/runtime/helpers/esm/extends";
import _objectWithoutPropertiesLoose from "@babel/runtime/helpers/esm/objectWithoutPropertiesLoose";
import * as React from 'react';
import * as ReactDOM from 'react-dom';
import * as PropTypes from 'prop-types';
import { mount as enzymeMount } from 'enzyme';
/**
 * Can't just mount <React.Fragment>{node}</React.Fragment>
 * because that swallows wrapper.setProps
 *
 * why class component:
 * https://github.com/airbnb/enzyme/issues/2043
 */
// eslint-disable-next-line react/prefer-stateless-function

class Mode extends React.Component {
  render() {
    // Excess props will come from e.g. enzyme setProps
    const _this$props = this.props,
          {
      __element,
      __strict
    } = _this$props,
          other = _objectWithoutPropertiesLoose(_this$props, ["__element", "__strict"]);

    const Component = __strict ? React.StrictMode : React.Fragment;
    return /*#__PURE__*/React.createElement(Component, null, /*#__PURE__*/React.cloneElement(__element, other));
  }

}

process.env.NODE_ENV !== "production" ? Mode.propTypes = {
  /**
   * this is essentially children. However we can't use children because then
   * using `wrapper.setProps({ children })` would work differently if this component
   * would be the root.
   */
  __element: PropTypes.element.isRequired,
  __strict: PropTypes.bool.isRequired
} : void 0;
let warnedOnce = false; // Generate an enhanced mount function.

export default function createMount(options = {}) {
  if (!warnedOnce) {
    warnedOnce = true;
    console.warn(['Material-UI: the test utils are deprecated, they are no longer present in v5.', 'The helpers were designed to work with enzyme.', 'However, the tests of the core components were moved to react-testing-library.'].join('\n'));
  }

  const {
    mount = enzymeMount,
    strict: globalStrict
  } = options,
        globalEnzymeOptions = _objectWithoutPropertiesLoose(options, ["mount", "strict"]);

  const attachTo = document.createElement('div');
  attachTo.className = 'app';
  attachTo.setAttribute('id', 'app');
  document.body.insertBefore(attachTo, document.body.firstChild);

  const mountWithContext = function mountWithContext(node, localOptions = {}) {
    const {
      disableUnnmount = false,
      strict = globalStrict
    } = localOptions,
          localEnzymeOptions = _objectWithoutPropertiesLoose(localOptions, ["disableUnnmount", "strict"]);

    if (!disableUnnmount) {
      ReactDOM.unmountComponentAtNode(attachTo);
    } // some tests require that no other components are in the tree
    // e.g. when doing .instance(), .state() etc.


    return mount(strict == null ? node : /*#__PURE__*/React.createElement(Mode, {
      __element: node,
      __strict: Boolean(strict)
    }), _extends({
      attachTo
    }, globalEnzymeOptions, localEnzymeOptions));
  };

  mountWithContext.attachTo = attachTo;

  mountWithContext.cleanUp = () => {
    ReactDOM.unmountComponentAtNode(attachTo);
    attachTo.parentElement.removeChild(attachTo);
  };

  return mountWithContext;
}