render.tsx

import TestRenderer from 'react-test-renderer';
import type { ReactTestInstance, ReactTestRenderer } from 'react-test-renderer';
import * as React from 'react';
import act from './act';
import { addToCleanupQueue } from './cleanup';
import debugShallow from './helpers/debugShallow';
import debugDeep from './helpers/debugDeep';
import { getQueriesForElement } from './within';

type Options = {
  wrapper?: React.ComponentType<any>;
  createNodeMock?: (element: React.ReactElement) => any;
};
type TestRendererOptions = {
  createNodeMock: (element: React.ReactElement) => any;
};

/**
 * Renders test component deeply using react-test-renderer and exposes helpers
 * to assert on the output.
 */
export default function render<T>(
  component: React.ReactElement<T>,
  { wrapper: Wrapper, createNodeMock }: Options = {}
) {
  const wrap = (innerElement: React.ReactElement) =>
    Wrapper ? <Wrapper>{innerElement}</Wrapper> : innerElement;

  const renderer = renderWithAct(
    wrap(component),
    createNodeMock ? { createNodeMock } : undefined
  );
  const update = updateWithAct(renderer, wrap);
  const instance = renderer.root;
  const unmount = () => {
    act(() => {
      renderer.unmount();
    });
  };

  addToCleanupQueue(unmount);

  return {
    ...getQueriesForElement(instance),
    update,
    unmount,
    container: instance,
    rerender: update, // alias for `update`
    toJSON: renderer.toJSON,
    debug: debug(instance, renderer),
  };
}

function renderWithAct(
  component: React.ReactElement,
  options?: TestRendererOptions
): ReactTestRenderer {
  let renderer: ReactTestRenderer;

  act(() => {
    renderer = TestRenderer.create(component, options);
  });

  // @ts-ignore act is sync, so renderer is always initialised here
  return renderer;
}

function updateWithAct(
  renderer: ReactTestRenderer,
  wrap: (innerElement: React.ReactElement) => React.ReactElement
) {
  return function (component: React.ReactElement) {
    act(() => {
      renderer.update(wrap(component));
    });
  };
}

interface DebugFunction {
  (message?: string): void;
  shallow: (message?: string) => void;
}

function debug(
  instance: ReactTestInstance,
  renderer: ReactTestRenderer
): DebugFunction {
  function debugImpl(message?: string) {
    const json = renderer.toJSON();
    if (json) {
      return debugDeep(json, message);
    }
  }
  debugImpl.shallow = (message?: string) => debugShallow(instance, message);
  return debugImpl;
}