## Overview
**Internal React repo tests only**
Depends on https://github.com/facebook/react/pull/28710
Adds three new assertions:
- `assertConsoleLogDev`
- `assertConsoleWarnDev`
- `assertConsoleErrorDev`
These will replace this pattern:
```js
await expect(async () => {
await expect(async () => {
await act(() => {
root.render(<Fail />)
});
}).toThrow();
}).toWarnDev('Warning');
```
With this:
```js
await expect(async () => {
await act(() => {
root.render(<Fail />)
});
}).toThrow();
assertConsoleWarnDev('Warning');
```
It works similar to our other `assertLog` matchers which clear the log
and assert on it, failing the tests if the log is not asserted before
the test ends.
## Diffs
There are a few improvements I also added including better log diffs and
more logging.
When there's a failure, the output will look something like:
<img width="655" alt="Screenshot 2024-04-03 at 11 50 08 AM"
src="https://github.com/facebook/react/assets/2440089/0c4bf1b2-5f63-4204-8af3-09e0c2d752ad">
Check out the test suite for snapshots of all the failures we may log.
In prod, the `_owner` field is only used for string refs so if we have
string refs disabled, we don't need this field. In fact, that's one of
the big benefits of deprecating them.
Depends on:
- #28317
- #28320
---
Changes the behavior of the JSX runtime to pass through `ref` as a
normal prop, rather than plucking it from the props object and storing
on the element.
This is a breaking change since it changes the type of the receiving
component. However, most code is unaffected since it's unlikely that a
component would have attempted to access a `ref` prop, since it was not
possible to get a reference to one.
`forwardRef` _will_ still pluck `ref` from the props object, though,
since it's extremely common for users to spread the props object onto
the inner component and pass `ref` as a differently named prop. This is
for maximum compatibility with existing code — the real impact of this
change is that `forwardRef` is no longer required.
Currently, refs are resolved during child reconciliation and stored on
the fiber. As a result of this change, we can move ref resolution to
happen only much later, and only for components that actually use them.
Then we can remove the `ref` field from the Fiber type. I have not yet
done that in this step, though.
This is not a public API. We only use it for our internal tests, the
ones in this repo. Let's move it to this private package. Practically
speaking this will also let us use async/await in the implementation.
**This commit only affects the internal version of `act` that we use in
this repo. The public `act` API is unaffected, for now.**
We should always await the result of an `act` call so that any work
queued in a microtask has a chance to flush. Neglecting to do this can
cause us to miss bugs when testing React behavior.
I codemodded all the existing `act` callers in previous PRs.
(This only affects our own internal repo; it's not a public API.)
I think most of us agree this is a less confusing name. It's possible
someone will confuse it with `console.log`. If that becomes a problem we
can warn in dev or something.
Over the years, we've gradually aligned on a set of best practices for
for testing concurrent React features in this repo. The default in most
cases is to use `act`, the same as you would do when testing a real
React app. However, because we're testing React itself, as opposed to an
app that uses React, our internal tests sometimes need to make
assertions on intermediate states that `act` intentionally disallows.
For those cases, we built a custom set of Jest assertion matchers that
provide greater control over the concurrent work queue. It works by
mocking the Scheduler package. (When we eventually migrate to using
native postTask, it would probably work by stubbing that instead.)
A problem with these helpers that we recently discovered is, because
they are synchronous function calls, they aren't sufficient if the work
you need to flush is scheduled in a microtask — we don't control the
microtask queue, and can't mock it.
`act` addresses this problem by encouraging you to await the result of
the `act` call. (It's not currently required to await, but in future
versions of React it likely will be.) It will then continue flushing
work until both the microtask queue and the Scheduler queue is
exhausted.
We can follow a similar strategy for our custom test helpers, by
replacing the current set of synchronous helpers with a corresponding
set of async ones:
- `expect(Scheduler).toFlushAndYield(log)` -> `await waitForAll(log)`
- `expect(Scheduler).toFlushAndYieldThrough(log)` -> `await
waitFor(log)`
- `expect(Scheduler).toFlushUntilNextPaint(log)` -> `await
waitForPaint(log)`
These APIs are inspired by the existing best practice for writing e2e
React tests. Rather than mock all task queues, in an e2e test you set up
a timer loop and wait for the UI to match an expecte condition. Although
we are mocking _some_ of the task queues in our tests, the general
principle still holds: it makes it less likely that our tests will
diverge from real world behavior in an actual browser.
In this commit, I've implemented the new testing helpers and converted
one of the Suspense tests to use them. In subsequent steps, I'll codemod
the rest of our test suite.
## Summary
Fixes "ReferenceError: You are trying to access a property or method of
the Jest environment after it has been torn down." in
`ReactIncrementalErrorHandling-test.internal.js`
Alternatives:
1. Additional `await act(cb)` call where `cb` makes sure we can flush
until next paint without throwing
```js
// Ensure test isn't exited with pending work
await act(async () => {
root.render(<App shouldThrow={false} />);
});
```
1. Use `toFlushAndThrow`
```diff
- let error;
- try {
- await act(async () => {
- root.render(<App shouldThrow={true} />);
- });
- } catch (e) {
- error = e;
- }
+ root.render(<App shouldThrow={true} />);
- expect(error.message).toBe('Oops!');
+ expect(Scheduler).toFlushAndThrow('Oops!');
expect(numberOfThrows < 100).toBe(true);
```
But then it still wouldn't make sense to pass `resolve` and `reject` to
the next `flushActWork`. Even if the next `flushActWork` would flush
until next paint without throwing, we couldn't resolve or reject because
we already did reject.
## How did you test this change?
- `yarn test --watch
packages/react-reconciler/src/__tests__/ReactIncrementalErrorHandling-test.internal.js`
produces no more errors after the test finishes.
## Summary
- yarn.lock diff +-6249, **small pr**
- use jest-environment-jsdom by default
- uncaught error from jsdom is an error object instead of strings
- abortSignal.reason is read-only in jsdom and node,
https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal/reason
## How did you test this change?
ci green
---------
Co-authored-by: Sebastian Silbermann <silbermann.sebastian@gmail.com>
This setting is an incremental path to the next Flow version enforcing
type annotations on most functions (except some inline callbacks).
Used
```
node_modules/.bin/flow codemod annotate-functions-and-classes --write .
```
to add a majority of the types with some hand cleanup when for large
inferred objects that should just be `Fiber` or weird constructs
including `any`.
Suppressed the remaining issues.
Builds on #25918
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
- method unbinding is no longer supported in Flow for soundness, this added a bunch of suppressions
- Flow now prevents objects to be supertypes of interfaces/classes
ghstack-source-id: d7749cbad8
Pull Request resolved: https://github.com/facebook/react/pull/25412
* Internal `act`: Unwrapping resolved promises
This update our internal implementation of `act` to support React's new
behavior for unwrapping promises. Like we did with Scheduler, when
something suspends, it will yield to the main thread so the microtasks
can run, then continue in a new task.
I need to implement the same behavior in the public version of `act`,
but there are some additional considerations so I'll do that in a
separate commit.
* Move throwException to after work loop resumes
throwException is the function that finds the nearest boundary and
schedules it for a second render pass. We should only call it right
before we unwind the stack — not if we receive an immediate ping and
render the fiber again.
This was an oversight in 8ef3a7c that I didn't notice because it happens
to mostly work, anyway. What made me notice the mistake is that
throwException also marks the entire render phase as suspended
(RootDidSuspend or RootDidSuspendWithDelay), which is only supposed to
be happen if we show a fallback. One consequence was that, in the
RootDidSuspendWithDelay case, the entire commit phase was blocked,
because that's the exit status we use to block a bad fallback
from appearing.
* Use expando to check whether promise has resolved
Add a `status` expando to a thrown thenable to track when its value has
resolved.
In a later step, we'll also use `value` and `reason` expandos to track
the resolved value.
This is not part of the official JavaScript spec — think of
it as an extension of the Promise API, or a custom interface that is a
superset of Thenable. However, it's inspired by the terminology used
by `Promise.allSettled`.
The intent is that this will be a public API — Suspense implementations
can set these expandos to allow React to unwrap the value synchronously
without waiting a microtask.
* Scaffolding for `experimental_use` hook
Sets up a new experimental hook behind a feature flag, but does not
implement it yet.
* use(promise)
Adds experimental support to Fiber for unwrapping the value of a promise
inside a component. It is not yet implemented for Server Components,
but that is planned.
If promise has already resolved, the value can be unwrapped
"immediately" without showing a fallback. The trick we use to implement
this is to yield to the main thread (literally suspending the work
loop), wait for the microtask queue to drain, then check if the promise
resolved in the meantime. If so, we can resume the last attempted fiber
without unwinding the stack. This functionality was implemented in
previous commits.
Another feature is that the promises do not need to be cached between
attempts. Because we assume idempotent execution of components, React
will track the promises that were used during the previous attempt and
reuse the result. You shouldn't rely on this property, but during
initial render it mostly just works. Updates are trickier, though,
because if you used an uncached promise, we have no way of knowing
whether the underlying data has changed, so we have to unwrap the
promise every time. It will still work, but it's inefficient and can
lead to unnecessary fallbacks if it happens during a discrete update.
When we implement this for Server Components, this will be less of an
issue because there are no updates in that environment. However, it's
still better for performance to cache data requests, so the same
principles largely apply.
The intention is that this will eventually be the only supported way to
suspend on arbitrary promises. Throwing a promise directly will
be deprecated.
If a hydration root receives an update before the outermost shell has
finished hydrating, we should give up hydrating and switch to
client rendering.
Since the shell is expected to commit quickly, this doesn't happen that
often. The most common sequence is something in the shell suspends, and
then the user quickly navigates to a different screen, triggering a
top-level update.
Instead of immediately switching to client rendering, we could first
attempt to hydration at higher priority, like we do for updates that
occur inside nested dehydrated trees.
But since this case is expected to be rare, and mainly only happens when
the shell is suspended, an attempt at higher priority would likely end
up suspending again anyway, so it would be wasted effort. Implementing
it this way would also require us to add a new lane especially for root
hydration. For simplicity's sake, we'll immediately switch to client
rendering. In the future, if we find another use case for a root
hydration lane, we'll reconsider.
* Extract `act` environment check into function
`act` checks the environment to determine whether to fire a warning.
We're changing how this check works in React 18. As a first step, this
refactors the logic into a single function. No behavior changes yet.
* Use IS_REACT_ACT_ENVIRONMENT to disable warnings
If `IS_REACT_ACT_ENVIRONMENT` is set to `false`, we will suppress
any `act` warnings. Otherwise, the behavior of `act` is the same as in
React 17: if `jest` is defined, it warns.
In concurrent mode, the plan is to remove the `jest` check and only warn
if `IS_REACT_ACT_ENVIRONMENT` is true. I have not implemented that
part yet.
* Hoist error codes import to module scope
When this code was written, the error codes map (`codes.json`) was
created on-the-fly, so we had to lazily require from inside the visitor.
Because `codes.json` is now checked into source, we can import it a
single time in module scope.
* Minify error constructors in production
We use a script to minify our error messages in production. Each message
is assigned an error code, defined in `scripts/error-codes/codes.json`.
Then our build script replaces the messages with a link to our
error decoder page, e.g. https://reactjs.org/docs/error-decoder.html/?invariant=92
This enables us to write helpful error messages without increasing the
bundle size.
Right now, the script only works for `invariant` calls. It does not work
if you throw an Error object. This is an old Facebookism that we don't
really need, other than the fact that our error minification script
relies on it.
So, I've updated the script to minify error constructors, too:
Input:
Error(`A ${adj} message that contains ${noun}`);
Output:
Error(formatProdErrorMessage(ERR_CODE, adj, noun));
It only works for constructors that are literally named Error, though we
could add support for other names, too.
As a next step, I will add a lint rule to enforce that errors written
this way must have a corresponding error code.
* Minify "no fallback UI specified" error in prod
This error message wasn't being minified because it doesn't use
invariant. The reason it didn't use invariant is because this particular
error is created without begin thrown — it doesn't need to be thrown
because it's located inside the error handling part of the runtime.
Now that the error minification script supports Error constructors, we
can minify it by assigning it a production error code in
`scripts/error-codes/codes.json`.
To support the use of Error constructors more generally, I will add a
lint rule that enforces each message has a corresponding error code.
* Lint rule to detect unminified errors
Adds a lint rule that detects when an Error constructor is used without
a corresponding production error code.
We already have this for `invariant`, but not for regular errors, i.e.
`throw new Error(msg)`. There's also nothing that enforces the use of
`invariant` besides convention.
There are some packages where we don't care to minify errors. These are
packages that run in environments where bundle size is not a concern,
like react-pg. I added an override in the ESLint config to ignore these.
* Temporarily add invariant codemod script
I'm adding this codemod to the repo temporarily, but I'll revert it
in the same PR. That way we don't have to check it in but it's still
accessible (via the PR) if we need it later.
* [Automated] Codemod invariant -> Error
This commit contains only automated changes:
npx jscodeshift -t scripts/codemod-invariant.js packages --ignore-pattern="node_modules/**/*"
yarn linc --fix
yarn prettier
I will do any manual touch ups in separate commits so they're easier
to review.
* Remove temporary codemod script
This reverts the codemod script and ESLint config I added temporarily
in order to perform the invariant codemod.
* Manual touch ups
A few manual changes I made after the codemod ran.
* Enable error code transform per package
Currently we're not consistent about which packages should have their
errors minified in production and which ones should.
This adds a field to the bundle configuration to control whether to
apply the transform. We should decide what the criteria is going
forward. I think it's probably a good idea to minify any package that
gets sent over the network. So yes to modules that run in the browser,
and no to modules that run on the server and during development only.
* Move internal version of act to shared module
No reason to have three different copies of this anymore.
I've left the the renderer-specific `act` entry points because legacy
mode tests need to also be wrapped in `batchedUpdates`. Next, I'll update
the tests to use `batchedUpdates` manually when needed.
* Migrates tests to use internal module directly
Instead of the `unstable_concurrentAct` exports. Now we can drop those
from the public builds.
I put it in the jest-react package since that's where we put our other
testing utilities (like `toFlushAndYield`). Not so much so it can be
consumed publicly (nobody uses that package except us), but so it works
with our build tests.
* Remove unused internal fields
These were used by the old act implementation. No longer needed.
* Remove redundant initial of isArray (#21163)
* Reapply prettier
* Type the isArray function with refinement support
This ensures that an argument gets refined just like it does if isArray is
used directly.
I'm not sure how to express with just a direct reference so I added a
function wrapper and confirmed that this does get inlined properly by
closure compiler.
* A few more
* Rename unit test to internal
This is not testing a bundle.
Co-authored-by: Behnam Mohammadi <itten@live.com>
* Enable prefer-const rule
Stylistically I don't like this but Closure Compiler takes advantage of
this information.
* Auto-fix lints
* Manually fix the remaining callsites
* Swap expect(ReactNoop) for expect(Scheduler)
In the previous commits, I upgraded our custom Jest matchers for the
noop and test renderers to use Scheduler under the hood.
Now that all these matchers are using Scheduler, we can drop
support for passing ReactNoop and test roots and always pass
Scheduler directly.
* Externalize Scheduler in noop and test bundles
I also noticed we don't need to regenerator runtime in noop anymore.
* Replace test renderer's fake Scheduler implementation with mock build
The test renderer has its own mock implementation of the Scheduler
interface, with the ability to partially render work in tests. Now that
this functionality has been lifted into a proper mock Scheduler build,
we can use that instead.
* Fix Profiler tests in prod
Found a bug related to suspending inside an already mounted tree. While
investigating this I noticed we really don't have much coverage of
suspended updates. I think this would greatly benefit from some fuzz
testing; still haven't thought of a good test case, though.
* Store the start time on `updateQueue` instead of `stateNode`
Originally I did this to free the `stateNode` field to store a second
set of children. I don't we'll need this anymore, since we use fragment
fibers instead. But I still think using `updateQueue` makes more sense
so I'll leave this in.
* Use fragment fibers to keep the primary and fallback children separate
If the children timeout, we switch to showing the fallback children in
place of the "primary" children. However, we don't want to delete the
primary children because then their state will be lost (both the React
state and the host state, e.g. uncontrolled form inputs). Instead we
keep them mounted and hide them. Both the fallback children AND the
primary children are rendered at the same time. Once the primary
children are un-suspended, we can delete the fallback children — don't
need to preserve their state.
The two sets of children are siblings in the host environment, but
semantically, for purposes of reconciliation, they are two separate
sets. So we store them using two fragment fibers.
However, we want to avoid allocating extra fibers for every placeholder.
They're only necessary when the children time out, because that's the
only time when both sets are mounted.
So, the extra fragment fibers are only used if the children time out.
Otherwise, we render the primary children directly. This requires some
custom reconciliation logic to preserve the state of the primary
children. It's essentially a very basic form of re-parenting.
* Use `memoizedState` to store various pieces of SuspenseComponent's state
SuspenseComponent has three pieces of state:
- alreadyCaptured: Whether a component in the child subtree already
suspended. If true, subsequent suspends should bubble up to the
next boundary.
- didTimeout: Whether the boundary renders the primary or fallback
children. This is separate from `alreadyCaptured` because outside of
strict mode, when a boundary times out, the first commit renders the
primary children in an incomplete state, then performs a second commit
to switch the fallback. In that first commit, `alreadyCaptured` is
false and `didTimeout` is true.
- timedOutAt: The time at which the boundary timed out. This is separate
from `didTimeout` because it's not set unless the boundary
actually commits.
These were previously spread across several fields.
This happens to make the non-strict case a bit less hacky; the logic for
that special case is now mostly localized to the UnwindWork module.
* Hide timed-out Suspense children
When a subtree takes too long to load, we swap its contents out for
a fallback to unblock the rest of the tree. Because we don't want
to lose the state of the timed out view, we shouldn't actually delete
the nodes from the tree. Instead, we'll keep them mounted and hide
them visually. When the subtree is unblocked, we un-hide it, having
preserved the existing state.
Adds additional host config methods. For mutation mode:
- hideInstance
- hideTextInstance
- unhideInstance
- unhideTextInstance
For persistent mode:
- cloneHiddenInstance
- cloneUnhiddenInstance
- createHiddenTextInstance
I've only implemented the new methods in the noop and test renderers.
I'll implement them in the other renderers in subsequent commits.
* Include `hidden` prop in noop renderer's output
This will be used in subsequent commits to test that timed-out children
are properly hidden.
Also adds getChildrenAsJSX() method as an alternative to using
getChildren(). (Ideally all our tests would use test renderer #oneday.)
* Implement hide/unhide host config methods for DOM renderer
For DOM nodes, we hide using `el.style.display = 'none'`.
Text nodes don't have style, so we hide using `text.textContent = ''`.
* Implement hide/unhide host config methods for Art renderer
* Create DOM fixture that tests state preservation of timed out content
* Account for class components that suspend outside concurrent mode
Need to distinguish mount from update. An unfortunate edge case :(
* Fork appendAllChildren between persistent and mutation mode
* Remove redundant check for existence of el.style
* Schedule placement effect on indeterminate components
In non-concurrent mode, indeterminate fibers may commit in an
inconsistent state. But when they update, we should throw out the
old fiber and start fresh. Which means the new fiber needs a
placement effect.
* Pass null instead of current everywhere in mountIndeterminateComponent
* Jest + test renderer helpers for concurrent mode
Most of our concurrent React tests use the noop renderer. But most
of those tests don't test the renderer API, and could instead be
written with the test renderer. We should switch to using the test
renderer whenever possible, because that's what we expect product devs
and library authors to do. If test renderer is sufficient for writing
most React core tests, it should be sufficient for others, too. (The
converse isn't true but we should aim to dogfood test renderer as much
as possible.)
This PR adds a new package, jest-react (thanks @cpojer). I've moved
our existing Jest matchers into that package and added some new ones.
I'm not expecting to figure out the final API in this PR. My goal is
to land something good enough that we can start dogfooding in www.
TODO: Continue migrating Suspense tests, decide on better API names
* Add additional invariants to prevent common errors
- Errors if user attempts to flush when log of yields is not empty
- Throws if argument passed to toClearYields is not ReactTestRenderer
* Better method names
- toFlushAll -> toFlushAndYield
- toFlushAndYieldThrough ->
- toClearYields -> toHaveYielded
Also added toFlushWithoutYielding
* Fix jest-react exports
* Tweak README
