| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | * |
| 7 | * @emails react-core |
| 8 | */ |
| 9 | |
| 10 | 'use strict'; |
| 11 | |
| 12 | let useSyncExternalStore; |
| 13 | let React; |
| 14 | let ReactNoop; |
| 15 | let Scheduler; |
| 16 | let act; |
| 17 | let useLayoutEffect; |
| 18 | let forwardRef; |
| 19 | let useImperativeHandle; |
| 20 | let useRef; |
| 21 | let useState; |
| 22 | let use; |
| 23 | let startTransition; |
| 24 | let waitFor; |
| 25 | let waitForAll; |
| 26 | let assertLog; |
| 27 | let Suspense; |
| 28 | let useMemo; |
| 29 | let textCache; |
| 30 | |
| 31 | // This tests the native useSyncExternalStore implementation, not the shim. |
| 32 | // Tests that apply to both the native implementation and the shim should go |
| 33 | // into useSyncExternalStoreShared-test.js. The reason they are separate is |
| 34 | // because at some point we may start running the shared tests against vendored |
| 35 | // React DOM versions (16, 17, etc) instead of React Noop. |
| 36 | describe('useSyncExternalStore', () => { |
| 37 | beforeEach(() => { |
| 38 | jest.resetModules(); |
| 39 | |
| 40 | React = require('react'); |
| 41 | ReactNoop = require('react-noop-renderer'); |
| 42 | Scheduler = require('scheduler'); |
| 43 | useLayoutEffect = React.useLayoutEffect; |
| 44 | useImperativeHandle = React.useImperativeHandle; |
| 45 | forwardRef = React.forwardRef; |
| 46 | useRef = React.useRef; |
| 47 | useState = React.useState; |
| 48 | use = React.use; |
| 49 | useSyncExternalStore = React.useSyncExternalStore; |
| 50 | startTransition = React.startTransition; |
| 51 | Suspense = React.Suspense; |
| 52 | useMemo = React.useMemo; |
| 53 | textCache = new Map(); |
| 54 | const InternalTestUtils = require('internal-test-utils'); |
| 55 | waitFor = InternalTestUtils.waitFor; |
| 56 | waitForAll = InternalTestUtils.waitForAll; |
| 57 | assertLog = InternalTestUtils.assertLog; |
| 58 | |
| 59 | act = require('internal-test-utils').act; |
| 60 | }); |
| 61 | |
| 62 | function resolveText(text) { |
| 63 | const record = textCache.get(text); |
| 64 | if (record === undefined) { |
| 65 | const newRecord = { |
| 66 | status: 'resolved', |
| 67 | value: text, |
| 68 | }; |
| 69 | textCache.set(text, newRecord); |
| 70 | } else if (record.status === 'pending') { |
| 71 | const thenable = record.value; |
| 72 | record.status = 'resolved'; |
| 73 | record.value = text; |
| 74 | thenable.pings.forEach(t => t()); |
| 75 | } |
| 76 | } |
| 77 | function readText(text) { |
| 78 | const record = textCache.get(text); |
| 79 | if (record !== undefined) { |
| 80 | switch (record.status) { |
| 81 | case 'pending': |
| 82 | throw record.value; |
| 83 | case 'rejected': |
| 84 | throw record.value; |
| 85 | case 'resolved': |
| 86 | return record.value; |
| 87 | } |
| 88 | } else { |
| 89 | const thenable = { |
| 90 | pings: [], |
| 91 | then(resolve) { |
| 92 | if (newRecord.status === 'pending') { |
| 93 | thenable.pings.push(resolve); |
| 94 | } else { |
| 95 | Promise.resolve().then(() => resolve(newRecord.value)); |
| 96 | } |
| 97 | }, |
| 98 | }; |
| 99 | |
| 100 | const newRecord = { |
| 101 | status: 'pending', |
| 102 | value: thenable, |
| 103 | }; |
| 104 | textCache.set(text, newRecord); |
| 105 | |
| 106 | throw thenable; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | function AsyncText({text}) { |
| 111 | const result = readText(text); |
| 112 | Scheduler.log(text); |
| 113 | return result; |
| 114 | } |
| 115 | |
| 116 | function Text({text}) { |
| 117 | Scheduler.log(text); |
| 118 | return text; |
| 119 | } |
| 120 | |
| 121 | function createExternalStore(initialState) { |
| 122 | const listeners = new Set(); |
| 123 | let currentState = initialState; |
| 124 | return { |
| 125 | set(text) { |
| 126 | currentState = text; |
| 127 | ReactNoop.batchedUpdates(() => { |
| 128 | listeners.forEach(listener => listener()); |
| 129 | }); |
| 130 | }, |
| 131 | subscribe(listener) { |
| 132 | listeners.add(listener); |
| 133 | return () => listeners.delete(listener); |
| 134 | }, |
| 135 | getState() { |
| 136 | return currentState; |
| 137 | }, |
| 138 | getSubscriberCount() { |
| 139 | return listeners.size; |
| 140 | }, |
| 141 | }; |
| 142 | } |
| 143 | |
| 144 | it( |
| 145 | 'detects interleaved mutations during a concurrent read before ' + |
| 146 | 'layout effects fire', |
| 147 | async () => { |
| 148 | const store1 = createExternalStore(0); |
| 149 | const store2 = createExternalStore(0); |
| 150 | |
| 151 | const Child = forwardRef(({store, label}, ref) => { |
| 152 | const value = useSyncExternalStore(store.subscribe, store.getState); |
| 153 | useImperativeHandle(ref, () => { |
| 154 | return value; |
| 155 | }, []); |
| 156 | return <Text text={label + value} />; |
| 157 | }); |
| 158 | |
| 159 | function App({store}) { |
| 160 | const refA = useRef(null); |
| 161 | const refB = useRef(null); |
| 162 | const refC = useRef(null); |
| 163 | useLayoutEffect(() => { |
| 164 | // This layout effect reads children that depend on an external store. |
| 165 | // This demostrates whether the children are consistent when the |
| 166 | // layout phase runs. |
| 167 | const aText = refA.current; |
| 168 | const bText = refB.current; |
| 169 | const cText = refC.current; |
| 170 | Scheduler.log( |
| 171 | `Children observed during layout: A${aText}B${bText}C${cText}`, |
| 172 | ); |
| 173 | }); |
| 174 | return ( |
| 175 | <> |
| 176 | <Child store={store} ref={refA} label="A" /> |
| 177 | <Child store={store} ref={refB} label="B" /> |
| 178 | <Child store={store} ref={refC} label="C" /> |
| 179 | </> |
| 180 | ); |
| 181 | } |
| 182 | |
| 183 | const root = ReactNoop.createRoot(); |
| 184 | await act(async () => { |
| 185 | // Start a concurrent render that reads from the store, then yield. |
| 186 | startTransition(() => { |
| 187 | root.render(<App store={store1} />); |
| 188 | }); |
| 189 | |
| 190 | await waitFor(['A0', 'B0']); |
| 191 | |
| 192 | // During an interleaved event, the store is mutated. |
| 193 | store1.set(1); |
| 194 | |
| 195 | // Then we continue rendering. |
| 196 | await waitForAll([ |
| 197 | // C reads a newer value from the store than A or B, which means they |
| 198 | // are inconsistent. |
| 199 | 'C1', |
| 200 | |
| 201 | // Before committing the layout effects, React detects that the store |
| 202 | // has been mutated. So it throws out the entire completed tree and |
| 203 | // re-renders the new values. |
| 204 | 'A1', |
| 205 | 'B1', |
| 206 | 'C1', |
| 207 | // The layout effects reads consistent children. |
| 208 | 'Children observed during layout: A1B1C1', |
| 209 | ]); |
| 210 | }); |
| 211 | |
| 212 | // Now we're going test the same thing during an update that |
| 213 | // switches stores. |
| 214 | await act(async () => { |
| 215 | startTransition(() => { |
| 216 | root.render(<App store={store2} />); |
| 217 | }); |
| 218 | |
| 219 | // Start a concurrent render that reads from the store, then yield. |
| 220 | await waitFor(['A0', 'B0']); |
| 221 | |
| 222 | // During an interleaved event, the store is mutated. |
| 223 | store2.set(1); |
| 224 | |
| 225 | // Then we continue rendering. |
| 226 | await waitForAll([ |
| 227 | // C reads a newer value from the store than A or B, which means they |
| 228 | // are inconsistent. |
| 229 | 'C1', |
| 230 | |
| 231 | // Before committing the layout effects, React detects that the store |
| 232 | // has been mutated. So it throws out the entire completed tree and |
| 233 | // re-renders the new values. |
| 234 | 'A1', |
| 235 | 'B1', |
| 236 | 'C1', |
| 237 | // The layout effects reads consistent children. |
| 238 | 'Children observed during layout: A1B1C1', |
| 239 | ]); |
| 240 | }); |
| 241 | }, |
| 242 | ); |
| 243 | |
| 244 | it('next value is correctly cached when state is dispatched in render phase', async () => { |
| 245 | const store = createExternalStore('value:initial'); |
| 246 | |
| 247 | function App() { |
| 248 | const value = useSyncExternalStore(store.subscribe, store.getState); |
| 249 | const [sameValue, setSameValue] = useState(value); |
| 250 | if (value !== sameValue) setSameValue(value); |
| 251 | return <Text text={value} />; |
| 252 | } |
| 253 | |
| 254 | const root = ReactNoop.createRoot(); |
| 255 | await act(() => { |
| 256 | // Start a render that reads from the store and yields value |
| 257 | root.render(<App />); |
| 258 | }); |
| 259 | assertLog(['value:initial']); |
| 260 | |
| 261 | await act(() => { |
| 262 | store.set('value:changed'); |
| 263 | }); |
| 264 | assertLog(['value:changed']); |
| 265 | |
| 266 | // If cached value was updated, we expect a re-render |
| 267 | await act(() => { |
| 268 | store.set('value:initial'); |
| 269 | }); |
| 270 | assertLog(['value:initial']); |
| 271 | }); |
| 272 | |
| 273 | it( |
| 274 | 'regression: suspending in shell after synchronously patching ' + |
| 275 | 'up store mutation', |
| 276 | async () => { |
| 277 | // Tests a case where a store is mutated during a concurrent event, then |
| 278 | // during the sync re-render, a synchronous render is triggered. |
| 279 | |
| 280 | const store = createExternalStore('Initial'); |
| 281 | |
| 282 | let resolve; |
| 283 | const promise = new Promise(r => { |
| 284 | resolve = r; |
| 285 | }); |
| 286 | |
| 287 | function A() { |
| 288 | const value = useSyncExternalStore(store.subscribe, store.getState); |
| 289 | |
| 290 | if (value === 'Updated') { |
| 291 | try { |
| 292 | use(promise); |
| 293 | } catch (x) { |
| 294 | Scheduler.log('Suspend A'); |
| 295 | throw x; |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | return <Text text={'A: ' + value} />; |
| 300 | } |
| 301 | |
| 302 | function B() { |
| 303 | const value = useSyncExternalStore(store.subscribe, store.getState); |
| 304 | return <Text text={'B: ' + value} />; |
| 305 | } |
| 306 | |
| 307 | function App() { |
| 308 | return ( |
| 309 | <> |
| 310 | <span> |
| 311 | <A /> |
| 312 | </span> |
| 313 | <span> |
| 314 | <B /> |
| 315 | </span> |
| 316 | </> |
| 317 | ); |
| 318 | } |
| 319 | |
| 320 | const root = ReactNoop.createRoot(); |
| 321 | await act(async () => { |
| 322 | // A and B both read from the same store. Partially render A. |
| 323 | startTransition(() => root.render(<App />)); |
| 324 | // A reads the initial value of the store. |
| 325 | await waitFor(['A: Initial']); |
| 326 | |
| 327 | // Before B renders, mutate the store. |
| 328 | store.set('Updated'); |
| 329 | }); |
| 330 | assertLog([ |
| 331 | // B reads the updated value of the store. |
| 332 | 'B: Updated', |
| 333 | // This should a synchronous re-render of A using the updated value. In |
| 334 | // this test, this causes A to suspend. |
| 335 | 'Suspend A', |
| 336 | // pre-warming |
| 337 | 'B: Updated', |
| 338 | ]); |
| 339 | // Nothing has committed, because A suspended and no fallback |
| 340 | // was provided. |
| 341 | expect(root).toMatchRenderedOutput(null); |
| 342 | |
| 343 | // Resolve the data and finish rendering. |
| 344 | await act(() => resolve()); |
| 345 | assertLog(['A: Updated', 'B: Updated']); |
| 346 | expect(root).toMatchRenderedOutput( |
| 347 | <> |
| 348 | <span>A: Updated</span> |
| 349 | <span>B: Updated</span> |
| 350 | </>, |
| 351 | ); |
| 352 | }, |
| 353 | ); |
| 354 | |
| 355 | // Regression test for https://github.com/facebook/react/issues/27670 |
| 356 | it('detects store mutations from a layout effect while an Activity subtree is being revealed', async () => { |
| 357 | const store = createExternalStore('revision:1'); |
| 358 | |
| 359 | function App({mode, revision}) { |
| 360 | return ( |
| 361 | <React.Activity mode={mode}> |
| 362 | <Wrapper revision={revision}> |
| 363 | <Subscriber /> |
| 364 | </Wrapper> |
| 365 | </React.Activity> |
| 366 | ); |
| 367 | } |
| 368 | |
| 369 | function Wrapper({children, revision}) { |
| 370 | useLayoutEffect(() => { |
| 371 | store.set('revision:' + revision); |
| 372 | }, [revision]); |
| 373 | |
| 374 | return ( |
| 375 | <> |
| 376 | wrapper:{revision} |
| 377 | {', '} |
| 378 | {children} |
| 379 | </> |
| 380 | ); |
| 381 | } |
| 382 | |
| 383 | function Subscriber() { |
| 384 | const revision = useSyncExternalStore(store.subscribe, store.getState); |
| 385 | return <Text text={revision} />; |
| 386 | } |
| 387 | |
| 388 | const root = ReactNoop.createRoot(); |
| 389 | |
| 390 | // Mount the app |
| 391 | await act(() => { |
| 392 | root.render(<App mode="visible" revision="1" />); |
| 393 | }); |
| 394 | assertLog(['revision:1']); |
| 395 | expect(root).toMatchRenderedOutput('wrapper:1, revision:1'); |
| 396 | expect(store.getSubscriberCount()).toBe(1); |
| 397 | |
| 398 | // Hide the subtree. React unsubscribes from the store. |
| 399 | await act(() => { |
| 400 | root.render(<App mode="hidden" revision="1" />); |
| 401 | }); |
| 402 | assertLog(['revision:1']); |
| 403 | expect(store.getSubscriberCount()).toBe(0); |
| 404 | |
| 405 | // Show the subtree again. A layout effect mutates the store during the |
| 406 | // reveal, after the Subscriber rendered but before it resubscribed. When |
| 407 | // it resubscribes, it must detect the mutation it missed. |
| 408 | await act(() => { |
| 409 | root.render(<App mode="visible" revision="2" />); |
| 410 | }); |
| 411 | assertLog(['revision:1', 'revision:2']); |
| 412 | expect(store.getSubscriberCount()).toBe(1); |
| 413 | expect(root).toMatchRenderedOutput('wrapper:2, revision:2'); |
| 414 | }); |
| 415 | |
| 416 | // Regression test for https://github.com/facebook/react/issues/27670 |
| 417 | it( |
| 418 | 'detects store mutations that happened while an Activity subtree was ' + |
| 419 | 'hidden, even if the subtree bails out of rendering when revealed', |
| 420 | async () => { |
| 421 | const store = createExternalStore('initial'); |
| 422 | |
| 423 | // Memoized so that revealing the Activity boundary doesn't re-render |
| 424 | // the subscriber. This matches components memoized by React.memo or |
| 425 | // React Compiler. |
| 426 | const Subscriber = React.memo(({label}) => { |
| 427 | const value = useSyncExternalStore(store.subscribe, store.getState); |
| 428 | return <Text text={label + ':' + value} />; |
| 429 | }); |
| 430 | |
| 431 | function App({mode, label}) { |
| 432 | return ( |
| 433 | <React.Activity mode={mode}> |
| 434 | <Subscriber label={label} /> |
| 435 | </React.Activity> |
| 436 | ); |
| 437 | } |
| 438 | |
| 439 | const root = ReactNoop.createRoot(); |
| 440 | await act(() => { |
| 441 | root.render(<App mode="visible" label="a" />); |
| 442 | }); |
| 443 | assertLog(['a:initial']); |
| 444 | expect(root).toMatchRenderedOutput('a:initial'); |
| 445 | expect(store.getSubscriberCount()).toBe(1); |
| 446 | |
| 447 | // Re-render the subscriber once with different props, with no store |
| 448 | // change. This replaces its effect list with one that contains only |
| 449 | // the subscription effect, no interleaved mutation check. |
| 450 | await act(() => { |
| 451 | root.render(<App mode="visible" label="b" />); |
| 452 | }); |
| 453 | assertLog(['b:initial']); |
| 454 | expect(root).toMatchRenderedOutput('b:initial'); |
| 455 | |
| 456 | // Hide the subtree. React unsubscribes from the store. |
| 457 | await act(() => { |
| 458 | root.render(<App mode="hidden" label="b" />); |
| 459 | }); |
| 460 | expect(store.getSubscriberCount()).toBe(0); |
| 461 | |
| 462 | // Mutate the store while the subtree is hidden. Nothing is subscribed, |
| 463 | // so no update is scheduled. |
| 464 | await act(() => { |
| 465 | store.set('updated'); |
| 466 | }); |
| 467 | assertLog([]); |
| 468 | |
| 469 | // Show the subtree again. The memoized component bails out of |
| 470 | // rendering, so resubscribing to the store is the only chance to |
| 471 | // detect the mutation that happened while it was hidden. |
| 472 | await act(() => { |
| 473 | root.render(<App mode="visible" label="b" />); |
| 474 | }); |
| 475 | assertLog(['b:updated']); |
| 476 | expect(store.getSubscriberCount()).toBe(1); |
| 477 | expect(root).toMatchRenderedOutput('b:updated'); |
| 478 | }, |
| 479 | ); |
| 480 | |
| 481 | it('regression: does not infinite loop for only changing store reference in render', async () => { |
| 482 | let store = {value: {}}; |
| 483 | let listeners = []; |
| 484 | |
| 485 | const ExternalStore = { |
| 486 | set(value) { |
| 487 | // Change the store ref, but not the value. |
| 488 | // This will cause a new snapshot to be returned if set is called in render, |
| 489 | // but the value is the same. Stores should not do this, but if they do |
| 490 | // we shouldn't infinitely render. |
| 491 | store = {...store}; |
| 492 | setTimeout(() => { |
| 493 | store = {value}; |
| 494 | emitChange(); |
| 495 | }, 100); |
| 496 | emitChange(); |
| 497 | }, |
| 498 | subscribe(listener) { |
| 499 | listeners = [...listeners, listener]; |
| 500 | return () => { |
| 501 | listeners = listeners.filter(l => l !== listener); |
| 502 | }; |
| 503 | }, |
| 504 | getSnapshot() { |
| 505 | return store; |
| 506 | }, |
| 507 | }; |
| 508 | |
| 509 | function emitChange() { |
| 510 | listeners.forEach(l => l()); |
| 511 | } |
| 512 | |
| 513 | function StoreText() { |
| 514 | const {value} = useSyncExternalStore( |
| 515 | ExternalStore.subscribe, |
| 516 | ExternalStore.getSnapshot, |
| 517 | ); |
| 518 | |
| 519 | useMemo(() => { |
| 520 | // Set the store value on mount. |
| 521 | // This breaks the rules of React, but should be handled gracefully. |
| 522 | const newValue = {text: 'B'}; |
| 523 | if (value == null || newValue !== value) { |
| 524 | ExternalStore.set(newValue); |
| 525 | } |
| 526 | }, []); |
| 527 | |
| 528 | return <Text text={value.text || '(not set)'} />; |
| 529 | } |
| 530 | |
| 531 | function App() { |
| 532 | return ( |
| 533 | <> |
| 534 | <Suspense fallback={'Loading...'}> |
| 535 | <AsyncText text={'A'} /> |
| 536 | <StoreText /> |
| 537 | </Suspense> |
| 538 | </> |
| 539 | ); |
| 540 | } |
| 541 | |
| 542 | const root = ReactNoop.createRoot(); |
| 543 | |
| 544 | // The initial render suspends. |
| 545 | await act(async () => { |
| 546 | root.render(<App />); |
| 547 | }); |
| 548 | |
| 549 | // pre-warming |
| 550 | assertLog(['(not set)']); |
| 551 | |
| 552 | expect(root).toMatchRenderedOutput('Loading...'); |
| 553 | |
| 554 | // Resolve the data and finish rendering. |
| 555 | // When resolving, the store should not get stuck in an infinite loop. |
| 556 | await act(() => { |
| 557 | resolveText('A'); |
| 558 | }); |
| 559 | assertLog([ |
| 560 | 'A', |
| 561 | 'B', |
| 562 | 'A', |
| 563 | 'B', |
| 564 | 'B', |
| 565 | ...(gate('alwaysThrottleRetries') ? [] : ['B']), |
| 566 | ]); |
| 567 | |
| 568 | expect(root).toMatchRenderedOutput('AB'); |
| 569 | }); |
| 570 | }); |