Drop support for React < 18.0.0-rc.1

Author: eps1lon

.github/workflows/validate.yml

@@ -12,15 +12,15 @@ on:
   pull_request: {}
 jobs:
   main:
-    continue-on-error: ${{ matrix.react != 'latest' }}
+    continue-on-error: ${{ matrix.react != 'current' }}
     # ignore all-contributors PRs
     if: ${{ !contains(github.head_ref, 'all-contributors') }}
     strategy:
       fail-fast: false
       matrix:
         # TODO: relax `'16.9.1'` to `16` once GitHub has 16.9.1 cached. 16.9.0 is broken due to https://github.com/nodejs/node/issues/40030
         node: [12, 14, '16.9.1']
-        react: [latest, next, experimental]
+        react: [current, next, experimental]
     runs-on: ubuntu-latest
     steps:
       - name: 🛑 Cancel Previous Runs
@@ -47,6 +47,7 @@ jobs:
       # https://reactjs.org/blog/2019/10/22/react-release-channels.html#using-the-next-channel-for-integration-testing
       - name: ⚛️ Setup react
         run: npm install react@${{ matrix.react }} react-dom@${{ matrix.react }}
+        if: ${{ matrix.react != 'current' }}
 
       - name: ▶️ Run validate script
         run: npm run validate

jest.config.js

@@ -53,14 +53,14 @@
     "dotenv-cli": "^4.0.0",
     "kcd-scripts": "^11.1.0",
     "npm-run-all": "^4.1.5",
-    "react": "^17.0.1",
-    "react-dom": "^17.0.1",
+    "react": "18.0.0-rc.1",
+    "react-dom": "18.0.0-rc.1",
     "rimraf": "^3.0.2",
     "typescript": "^4.1.2"
   },
   "peerDependencies": {
-    "react": "*",
-    "react-dom": "*"
+    "react": "18.0.0-rc.1",
+    "react-dom": "18.0.0-rc.1"
   },
   "eslintConfig": {
     "extends": "./node_modules/kcd-scripts/eslint.js",
@@ -69,14 +69,6 @@
       "react/no-adjacent-inline-elements": "off",
       "import/no-unassigned-import": "off",
       "import/named": "off",
-      "import/no-unresolved": [
-        "error",
-        {
-          "ignore": [
-            "react-dom/client"
-          ]
-        }
-      ],
       "testing-library/no-container": "off",
       "testing-library/no-dom-import": "off",
       "testing-library/no-unnecessary-act": "off",

package.json

@@ -8,7 +8,7 @@ jest.mock('react-dom/test-utils', () => ({
 
 beforeEach(() => {
   jest.resetModules()
-  asyncAct = require('../act-compat').asyncAct
+  asyncAct = require('../act-compat').default
   jest.spyOn(console, 'error').mockImplementation(() => {})
 })
 

src/__tests__/new-act.js

@@ -1,6 +1,5 @@
 import * as React from 'react'
 import ReactDOM from 'react-dom'
-import ReactDOMClient from 'react-dom/client'
 import ReactDOMServer from 'react-dom/server'
 import {fireEvent, render, screen} from '../'
 
@@ -110,23 +109,6 @@ test('flushes useEffect cleanup functions sync on unmount()', () => {
   expect(spy).toHaveBeenCalledTimes(1)
 })
 
-test('throws if `legacyRoot: false` is used with an incomaptible version', () => {
-  const isConcurrentReact = typeof ReactDOMClient.createRoot === 'function'
-
-  const performConcurrentRender = () => render(<div />, {legacyRoot: false})
-
-  // eslint-disable-next-line jest/no-if -- jest doesn't support conditional tests
-  if (isConcurrentReact) {
-    // eslint-disable-next-line jest/no-conditional-expect -- yes, jest still doesn't support conditional tests
-    expect(performConcurrentRender).not.toThrow()
-  } else {
-    // eslint-disable-next-line jest/no-conditional-expect -- yes, jest still doesn't support conditional tests
-    expect(performConcurrentRender).toThrowError(
-      `Attempted to use concurrent React with \`react-dom@${ReactDOM.version}\`. Be sure to use the \`next\` or \`experimental\` release channel (https://reactjs.org/docs/release-channels.html).`,
-    )
-  }
-})
-
 test('can be called multiple times on the same container', () => {
   const container = document.createElement('div')
 
@@ -169,3 +151,28 @@ test('hydrate will make the UI interactive', () => {
 
   expect(container).toHaveTextContent('clicked:1')
 })
+
+test('legacyRoot uses legacy ReactDOM.render', () => {
+  jest.spyOn(console, 'error').mockImplementation(() => {})
+  render(<div />, {legacyRoot: true})
+
+  expect(console.error).toHaveBeenCalledTimes(1)
+  expect(console.error).toHaveBeenNthCalledWith(
+    1,
+    "Warning: ReactDOM.render is no longer supported in React 18. Use createRoot instead. Until you switch to the new API, your app will behave as if it's running React 17. Learn more: https://reactjs.org/link/switch-to-createroot",
+  )
+})
+
+test('legacyRoot uses legacy ReactDOM.hydrate', () => {
+  jest.spyOn(console, 'error').mockImplementation(() => {})
+  const ui = <div />
+  const container = document.createElement('div')
+  container.innerHTML = ReactDOMServer.renderToString(ui)
+  render(ui, {container, hydrate: true, legacyRoot: true})
+
+  expect(console.error).toHaveBeenCalledTimes(1)
+  expect(console.error).toHaveBeenNthCalledWith(
+    1,
+    "Warning: ReactDOM.hydrate is no longer supported in React 18. Use hydrateRoot instead. Until you switch to the new API, your app will behave as if it's running React 17. Learn more: https://reactjs.org/link/switch-to-createroot",
+  )
+})