* Migrate conditional tests to gate pragma
I searched through the codebase for this pattern:
```js
describe('test suite', () => {
if (!__EXPERIMENTAL__) { // or some other condition
test("empty test so Jest doesn't complain", () => {});
return;
}
// Unless we're in experimental mode, none of the tests in this block
// will run.
})
```
and converted them to the `@gate` pragma instead.
The reason this pattern isn't preferred is because you end up disabling
more tests than you need to.
* Add flag for www release channels
Using a heuristic where I check a flag that is known to only be enabled
in www. I left a TODO to instead set the release channel explicitly in
each test config.
* Add pragma for feature testing: @gate
The `@gate` pragma declares under which conditions a test is expected to
pass.
If the gate condition passes, then the test runs normally (same as if
there were no pragma).
If the conditional fails, then the test runs and is *expected to fail*.
An alternative to `it.experimental` and similar proposals.
Examples
--------
Basic:
```js
// @gate enableBlocksAPI
test('passes only if Blocks API is available', () => {/*...*/})
```
Negation:
```js
// @gate !disableLegacyContext
test('depends on a deprecated feature', () => {/*...*/})
```
Multiple flags:
```js
// @gate enableNewReconciler
// @gate experimental
test('needs both useEvent and Blocks', () => {/*...*/})
```
Logical operators (yes, I'm sorry):
```js
// @gate experimental && (enableNewReconciler || disableSchedulerTimeoutBasedOnReactExpirationTime)
test('concurrent mode, doesn\'t work in old fork unless Scheduler timeout flag is disabled', () => {/*...*/})
```
Strings, and comparion operators
No use case yet but I figure eventually we'd use this to gate on
different release channels:
```js
// @gate channel === "experimental" || channel === "modern"
test('works in OSS experimental or www modern', () => {/*...*/})
```
How does it work?
I'm guessing those last two examples might be controversial. Supporting
those cases did require implementing a mini-parser.
The output of the transform is very straightforward, though.
Input:
```js
// @gate a && (b || c)
test('some test', () => {/*...*/})
```
Output:
```js
_test_gate(ctx => ctx.a && (ctx.b || ctx.c, 'some test'), () => {/*...*/});
```
It also works with `it`, `it.only`, and `fit`. It leaves `it.skip` and
`xit` alone because those tests are disabled anyway.
`_test_gate` is a global method that I set up in our Jest config. It
works about the same as the existing `it.experimental` helper.
The context (`ctx`) argument is whatever we want it to be. I set it up
so that it throws if you try to access a flag that doesn't exist. I also
added some shortcuts for common gating conditions, like `old`
and `new`:
```js
// @gate experimental
test('experimental feature', () => {/*...*/})
// @gate new
test('only passes in new reconciler', () => {/*...*/})
```
Why implement this as a pragma instead of a runtime API?
- Doesn't require monkey patching built-in Jest methods. Instead it
compiles to a runtime function that composes Jest's API.
- Will be easy to upgrade if Jest ever overhauls their API or we switch
to a different testing framework (unlikely but who knows).
- It feels lightweight so hopefully people won't feel gross using it.
For example, adding or removing a gate pragma will never affect the
indentation of the test, unlike if you wrapped the test in a
conditional block.
* Compatibility with console error/warning tracking
We patch console.error and console.warning to track unexpected calls
in our tests. If there's an unexpected call, we usually throw inside
an `afterEach` hook. However, that's too late for tests that we
expect to fail, because our `_test_gate` runtime can't capture the
error. So I also check for unexpected calls inside `_test_gate`.
* Move test flags to dedicated file
Added some instructions for how the flags are set up and how to
use them.
* Add dynamic version of gate API
Receives same flags as the pragma.
If we ever decide to revert the pragma, we can codemod them to use
this instead.
* Implement component stack extraction hack
* Normalize errors in tests
This drops the requirement to include owner to pass the test.
* Special case tests
* Add destructuring to force toObject which throws before the side-effects
This ensures that we don't double call yieldValue or advanceTime in tests.
Ideally we could use empty destructuring but ES lint doesn't like it.
* Cache the result in DEV
In DEV it's somewhat likely that we'll see many logs that add component
stacks. This could be slow so we cache the results of previous components.
* Fixture
* Add Reflect to lint
* Log if out of range.
* Fix special case when the function call throws in V8
In V8 we need to ignore the first line. Normally we would never get there
because the stacks would differ before that, but the stacks are the same if
we end up throwing at the same place as the control.
This reverts commit cf0081263c.
The changes to the test code relate to changes in JSDOM that come with Jest 25:
* Several JSDOM workarounds are no longer needed.
* Several tests made assertions to match incorrect JSDOM behavior (e.g. setAttribute calls) that JSDOM has now patched to match browsers.
* https://codesandbox.io/s/resets-value-of-datetime-input-to-fix-bugs-in-ios-safari-1ppwh
* JSDOM no longer triggers default actions when dispatching click events.
* https://codesandbox.io/s/beautiful-cdn-ugn8f
* JSDOM fixed (jsdom/jsdom#2700) a bug so that calling focus() on an already focused element does not dispatch a FocusEvent.
* JSDOM now supports passive events.
* JSDOM has improved support for custom CSS properties.
* But requires jsdom/cssstyle#112 to land to support webkit prefixed properties.
* ReactFiberReconciler -> ReactFiberReconciler.old
* Set up infra for react-reconciler fork
We're planning to land some significant refactors of the reconciler.
We want to be able to gradually roll out the new implementation side-by-
side with the existing one. So we'll create a short lived fork of the
react-reconciler package. Once the new implementation has stabilized,
we'll delete the old implementation and promote the new one.
This means, for as long as the fork exists, we'll need to maintain two
separate implementations. This sounds painful, but since the forks will
still be largely the same, most changes will not require two separate
implementations. In practice, you'll implement the change in the old
fork and then copy paste it to the new one.
This commit only sets up the build and testing infrastructure. It does
not actually fork any modules. I'll do that in subsequent PRs.
The forked version of the reconciler will be used to build a special
version of React DOM. I've called this build ReactDOMForked. It's only
built for www; there's no open source version.
The new reconciler is disabled by default. It's enabled in the
`yarn test-www-variant` command. The reconciler fork isn't really
related to the "variant" feature of the www builds, but I'm piggy
backing on that concept to avoid having to add yet another
testing dimension.
* Add ReactFlightServerConfig intermediate
This just forwards to the stream version of Flight which is itself forked
between Node and W3C streams.
The dom-relay goes directly to the Relay config though which allows it to
avoid the stream part of Flight.
* Separate streaming protocol into the Stream config
* Split streaming parts into the ReactFlightServerConfigStream
This decouples it so that the Relay implementation doesn't have to encode
the JSON to strings. Instead it can be fed the values as JSON objects and
do its own encoding.
* Split FlightClient into a basic part and a stream part
Same split as the server.
* Expose lower level async hooks to Relay
This requires an external helper file that we'll wire up internally.
* Rename to clarify that it's client-only
* Rename FizzStreamer to FizzServer for consistency
* Rename react-flight to react-client/flight
For consistency with react-server. Currently this just includes flight
but it could be expanded to include the whole reconciler.
* Add Relay Flight Build
* Rename ReactServerHostConfig to ReactServerStreamConfig
This will be the config specifically for streaming purposes.
There will be other configs for other purposes.
* Require deep for reconcilers
* Delete inline* files
* Delete react-reconciler/persistent
This no longer makes any sense because it react-reconciler takes
supportsMutation or supportsPersistence as options. It's no longer based
on feature flags.
* Fix jest mocking
* Fix Flow strategy
We now explicitly list which paths we want to be checked by a renderer.
For every other renderer config we ignore those paths.
Nothing is "any" typed. So if some transitive dependency isn't reachable
it won't be accidentally "any" that leaks.
In CI, we run our test suite against multiple build configurations. For
example, we run our tests in both dev and prod, and in both the
experimental and stable release channels. This is to prevent accidental
deviations in behavior between the different builds. If there's an
intentional deviation in behavior, the test author must account
for them.
However, we currently don't run tests against the www builds. That's
a problem, because it's common for features to land in www before they
land anywhere else, including the experimental release channel.
Typically we do this so we can gradually roll out the feature behind
a flag before deciding to enable it.
The way we test those features today is by mutating the
`shared/ReactFeatureFlags` module. There are a few downsides to this
approach, though. The flag is only overridden for the specific tests or
test suites where you apply the override. But usually what you want is
to run *all* tests with the flag enabled, to protect against unexpected
regressions.
Also, mutating the feature flags module only works when running the
tests against source, not against the final build artifacts, because the
ReactFeatureFlags module is inlined by the build script.
Instead, we should run the test suite against the www configuration,
just like we do for prod, experimental, and so on. I've added a new
command, `yarn test-www`. It automatically runs in CI.
Some of the www feature flags are dynamic; that is, they depend on
a runtime condition (i.e. a GK). These flags are imported from an
external module that lives in www. Those flags will be enabled for some
clients and disabled for others, so we should run the tests against
*both* modes.
So I've added a new global `__VARIANT__`, and a new test command `yarn
test-www-variant`. `__VARIANT__` is set to false by default; when
running `test-www-variant`, it's set to true.
If we were going for *really* comprehensive coverage, we would run the
tests against every possible configuration of feature flags: 2 ^
numberOfFlags total combinations. That's not practical, though, so
instead we only run against two combinations: once with `__VARIANT__`
set to `true`, and once with it set to `false`. We generally assume that
flags can be toggled independently, so in practice this should
be enough.
You can also refer to `__VARIANT__` in tests to detect which mode you're
running in. Or, you can import `shared/ReactFeatureFlags` and read the
specific flag you can about. However, we should stop mutating that
module going forward. Treat it as read-only.
In this commit, I have only setup the www tests to run against source.
I'll leave running against build for a follow up.
Many of our tests currently assume they run only in the default
configuration, and break when certain flags are toggled. Rather than fix
these all up front, I've hard-coded the relevant flags to the default
values. We can incrementally migrate those tests later.
* Add options for forked entry points
We currently fork .fb.js entry points. This adds a few more options.
.modern.fb.js - experimental FB builds
.classic.fb.js - stable FB builds
.fb.js - if no other FB build, use this for FB builds
.experimental.js - experimental builds
.stable.js - stable builds
.js - used if no other override exists
This will be used to have different ES exports for different builds.
* Switch React to named exports
* Export named exports from the export point itself
We need to re-export the Flow exported types so we can use them in our code.
We don't want to use the Flow types from upstream since it doesn't have the non-public APIs that we have.
This should be able to use export * but I don't know why it doesn't work.
This actually enables Flow typing of React which was just "any" before.
This exposed some Flow errors that needs fixing.
* Create forks for the react entrypoint
None of our builds expose all exports and they all differ in at least one
way, so we need four forks.
* Set esModule flag to false
We don't want to emit the esModule compatibility flag on our CommonJS
output. For now we treat our named exports as if they're CommonJS.
This is a potentially breaking change for scheduler (but all those apis
are unstable), react-is and use-subscription. However, it seems unlikely
that anyone would rely on this since these only have named exports.
* Remove unused Feature Flags
* Let jest observe the stable fork for stable tests
This lets it do the negative test by ensuring that the right tests fail.
However, this in turn will make other tests that are not behind
__EXPERIMENTAL__ fail. So I need to do that next.
* Put all tests that depend on exports behind __EXPERIMENTAL__
Since there's no way to override the exports using feature flags
in .intern.js anymore we can't use these APIs in stable.
The tradeoff here is that we can either enable the negative tests on
"stable" that means experimental are expected to fail, or we can disable
tests on stable. This is unfortunate since some of these APIs now run on
a "stable" config at FB instead of the experimental.
* Switch ReactDOM to named exports
Same strategy as React.
I moved the ReactDOMFB runtime injection to classic.fb.js
Since we only fork the entrypoint, the `/testing` entrypoint needs to
be forked too to re-export the same things plus `act`. This is a bit
unfortunate. If it becomes a pattern we can consider forking in the
module resolution deeply.
fix flow
* Fix ReactDOM Flow Types
Now that ReactDOM is Flow type checked we need to fix up its types.
* Configure jest to use stable entry for ReactDOM in non-experimental
* Remove additional FeatureFlags that are no longer needed
These are only flagging the exports and no implementation details so we
can control them fully through the export overrides.
The changes to the test code relate to changes in JSDOM that come with Jest 25:
* Several JSDOM workarounds are no longer needed.
* Several tests made assertions to match incorrect JSDOM behavior (e.g. setAttribute calls) that JSDOM has now patched to match browsers.
* https://codesandbox.io/s/resets-value-of-datetime-input-to-fix-bugs-in-ios-safari-1ppwh
* JSDOM no longer triggers default actions when dispatching click events.
* https://codesandbox.io/s/beautiful-cdn-ugn8f
* JSDOM fixed (jsdom/jsdom#2700) a bug so that calling focus() on an already focused element does not dispatch a FocusEvent.
* JSDOM now supports passive events.
* JSDOM has improved support for custom CSS properties.
* But requires jsdom/cssstyle#112 to land to support webkit prefixed properties.
* Skip abandoned project folders in Jest config
This fixes a problem that occurs after renaming a package.
* Fix test_build_devtools to run test-build-devtools
* Exclude console.error plugin for DevTools packages
* Use correct release channel for DevTools tests
This should fix the createRoot error.
* Fix TZ dependent test
* Change DT job dependencies
* Replace all warning/lowPriWarning with console calls
* Replace console.warn/error with a custom wrapper at build time
* Fail the build for console.error/warn() where we can't read the stack
* prep for codemod
* prep warnings
* rename lint rules
* codemod for ifs
* shim www functions
* Handle more cases in the transform
* Thanks De Morgan
* Run the codemod
* Delete the transform
* Fix up confusing conditions manually
* Fix up www shims to match expected API
* Also check for low-pri warning in the lint rule
* Replace Babel plugin with an ESLint plugin
* Fix ESLint rule violations
* Move shared conditions higher
* Test formatting nits
* Tweak ESLint rule
* Bugfix: inside else branch, 'if' tests are not satisfactory
* Use a stricter check for exactly if (__DEV__)
This makes it easier to see what's going on and matches dominant style in the codebase.
* Fix remaining files after stricter check
* Add Flight Build and Unify HostFormat Config between Flight and Fizz
* Add basic resolution of models
* Add basic Flight fixture
Demonstrates the streaming protocol.
* Rename to flight-server to distinguish from the client parts
* Add Flight Client package and entry point
* Fix fixture
Special version of Jest's `it` for experimental tests. Tests marked as
experimental will run **both** stable and experimental modes. In
experimental mode, they work the same as the normal Jest methods. In
stable mode, they are **expected to fail**. This means we can detect
when a test previously marked as experimental can be un-marked when the
feature becomes stable. It also reduces the chances that we accidentally
add experimental APIs to the stable builds before we intend.
I added corresponding methods for the focus and skip APIs:
- `fit` -> `fit.experimental`
- `it.only` -> `it.only.experimental` or `it.experimental.only`
- `xit` -> `xit.experimental`
- `it.skip` -> `it.skip.experimental` or `it.experimental.skip`
Since `it` is an alias of `test`, `test.experimental` works, too.
* Tests run in experimental mode by default
For local development, you usually want experiments enabled. Unless
the release channel is set with an environment variable, tests will
run with __EXPERIMENTAL__ set to `true`.
* Remove concurrent APIs from stable builds
Those who want to try concurrent mode should use the experimental
builds instead.
I've left the `unstable_` prefixed APIs in the Facebook build so we
can continue experimenting with them internally without blessing them
for widespread use.
* Turn on SSR flags in experimental build
* Remove prefixed concurrent APIs from www build
Instead we'll use the experimental builds when syncing to www.
* Remove "canary" from internal React version string
* Don't bother including `unstable_` in error
The method names don't get stripped out of the production bundles
because they are passed as arguments to the error decoder.
Let's just always use the unprefixed APIs in the messages.
* Set up experimental builds
The experimental builds are packaged exactly like builds in the stable
release channel: same file structure, entry points, and npm package
names. The goal is to match what will eventually be released in stable
as closely as possible, but with additional features turned on.
Versioning and Releasing
------------------------
The experimental builds will be published to the same registry and
package names as the stable ones. However, they will be versioned using
a separate scheme. Instead of semver versions, experimental releases
will receive arbitrary version strings based on their content hashes.
The motivation is to thwart attempts to use a version range to match
against future experimental releases. The only way to install or depend
on an experimental release is to refer to the specific version number.
Building
--------
I did not use the existing feature flag infra to configure the
experimental builds. The reason is because feature flags are designed
to configure a single package. They're not designed to generate multiple
forks of the same package; for each set of feature flags, you must
create a separate package configuration.
Instead, I've added a new build dimension called the **release
channel**. By default, builds use the **stable** channel. There's
also an **experimental** release channel. We have the option to add more
in the future.
There are now two dimensions per artifact: build type (production,
development, or profiling), and release channel (stable or
experimental). These are separate dimensions because they are
combinatorial: there are stable and experimental production builds,
stable and experimental developmenet builds, and so on.
You can add something to an experimental build by gating on
`__EXPERIMENTAL__`, similar to how we use `__DEV__`. Anything inside
these branches will be excluded from the stable builds.
This gives us a low effort way to add experimental behavior in any
package without setting up feature flags or configuring a new package.
* Rename lowPriorityWarning to lowPriorityWarningWithoutStack
This maintains parity with the other warning-like functions.
* Duplicate the toWarnDev tests to test toLowPriorityWarnDev
* Make a lowPriorityWarning version of warning.js
* Extract both variants in print-warning
Avoids parsing lowPriorityWarning.js itself as the way it forwards the
call to lowPriorityWarningWithoutStack is not analyzable.
* Idle updates should not be blocked by hidden work
Use the special `Idle` expiration time for updates that are triggered at
Scheduler's `IdlePriority`, instead of `Never`.
The key difference between Idle and Never¹ is that Never work can be
committed in an inconsistent state without tearing the UI. The main
example is offscreen content, like a hidden subtree.
¹ "Never" isn't the best name. I originally called it that because it
"never" expires, but neither does Idle. Since it's mostly used for
offscreen subtrees, we could call it "Offscreen." However, it's also
used for dehydrated Suspense boundaries, which are inconsistent in the
sense that they haven't finished yet, but aren't visibly inconsistent
because the server rendered HTML matches what the hydrated tree would
look like.
* Reset as early as possible using local variable
* Updates in a hidden effect should be Idle
I had made them Never to avoid an extra render when a hidden effect
updates the hidden component -- if they are Idle, we have to render once
at Idle, which bails out on the hidden subtree, then again at Never to
actually process the update -- but the problem of needing an extra
render pass to bail out hidden updates already exists and we should fix
that properly instead of adding yet another special case.
If a Scheduler profile runs without stopping, the event log will grow
unbounded. Eventually it will run out of memory and the VM will throw
an error.
To prevent this from happening, let's automatically stop the profiler
once the log exceeds a certain limit. We'll also print a warning with
advice to call `stopLoggingProfilingEvents` explicitly.
Upgraded from Babel 6 to Babel 7.
The only significant change seems to be the way `@babel/plugin-transform-classes` handles classes differently from `babel-plugin-transform-es2015-classes`. In regular mode, the former injects a `_createClass` function that increases the bundle size, and in the latter it removes the safeguard checks. However, this is okay because we don't all classes in new features, and we want to deprecate class usage in the future in the react repo.
Co-authored-by: Luna Ruan <luna@fb.com>
Co-authored-by: Abdul Rauf <abdulraufmujahid@gmail.com>
Co-authored-by: Maksim Markelov <maks-markel@mail.ru>
We have behaviour divergence for act() between prod and dev (specifically, act() + concurrent mode does not flush fallbacks in prod. This doesn't affect anyone in OSS yet)
We also don't have a good story for writing tests in prod (and what from what I gather, nobody really writes tests in prod mode).
We could have wiped out act() in prod builds, except that _we_ ourselves use act() for our tests when we run them in prod mode.
This PR is a compromise to all of this. We will log a warning if you try to use act() in prod mode, and we silence it in our test suites.
