* 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.
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.
* Add new mock build of Scheduler with flush, yield API
Test environments need a way to take control of the Scheduler queue and
incrementally flush work. Our current tests accomplish this either using
dynamic injection, or by using Jest's fake timers feature. Both of these
options are fragile and rely too much on implementation details.
In this new approach, we have a separate build of Scheduler that is
specifically designed for test environments. We mock the default
implementation like we would any other module; in our case, via Jest.
This special build has methods like `flushAll` and `yieldValue` that
control when work is flushed. These methods are based on equivalent
methods we've been using to write incremental React tests. Eventually
we may want to migrate the React tests to interact with the mock
Scheduler directly, instead of going through the host config like we
currently do.
For now, I'm using our custom static injection infrastructure to create
the two builds of Scheduler — a default build for DOM (which falls back
to a naive timer based implementation), and the new mock build. I did it
this way because it allows me to share most of the implementation, which
isn't specific to a host environment — e.g. everything related to the
priority queue. It may be better to duplicate the shared code instead,
especially considering that future environments (like React Native) may
have entirely forked implementations. I'd prefer to wait until the
implementation stabilizes before worrying about that, but I'm open to
changing this now if we decide it's important enough.
* Mock Scheduler in bundle tests, too
* Remove special case by making regex more restrictive
* Throw in tests if work is done before emptying log
Test renderer already does this. Makes it harder to miss unexpected
behavior by forcing you to assert on every logged value.
* Convert ReactNoop tests to use jest matchers
The matchers warn if work is flushed while the log is empty. This is
the pattern we already follow for test renderer. I've used the same APIs
as test renderer, so it should be easy to switch between the two.
* 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
Adds custom Jest matchers that help with writing async tests:
- `toFlushThrough`
- `toFlushAll`
- `toFlushAndThrow`
- `toClearYields`
Each one accepts an array of expected yielded values, to prevent
false negatives.
Eventually I imagine we'll want to publish this on npm.
* Added toWarnInDev matcher and connected to 1 test
* Added .toLowPriorityWarnDev() matcher
* Reply Jest spy with custom spy. Unregister spy after toWarnDev() so unexpected console.error/warn calls will fail tests.
* console warn/error throws immediately in tests by default (if not spied on)
* Pass-thru console message before erroring to make it easier to identify
* More robustly handle unexpected warnings within try/catch
* Error message includes remaining expected warnings in addition to unexpected warning
* use different eslint config for es6 and es5
* remove confusing eslint/baseConfig.js & add more eslint setting for es5, es6
* more clear way to run eslint on es5 & es6 file
* seperate ESNext, ES6, ES6 path, and use different lint config
* rename eslint config file & update eslint rules
* Undo yarn.lock changes
* Rename a file
* Remove unnecessary exceptions
* Refactor a little bit
* Refactor and tweak the logic
* Minor issues
* Add a test-only transform to catch infinite loops
* Only track iteration count, not time
This makes the detection dramatically faster, and is okay in our case because we don't have tests that iterate so much.
* Use clearer naming
* Set different limits for tests
* Fail tests with infinite loops even if the error was caught
* Add a test
* Extract Jest config into a separate file
* Refactor Jest scripts directory structure
Introduces a more consistent naming scheme.
* Add yarn test-bundles and yarn test-prod-bundles
Only files ending with -test.public.js are opted in (so far we don't have any).
* Fix error decoding for production bundles
GCC seems to remove `new` from `new Error()` which broke our proxy.
* Build production version of react-noop-renderer
This lets us test more bundles.
* Switch to blacklist (exclude .private.js tests)
* Rename tests that are currently broken against bundles to *-test.internal.js
Some of these are using private APIs. Some have other issues.
* Add bundle tests to CI
* Split private and public ReactJSXElementValidator tests
* Remove internal deps from ReactServerRendering-test and make it public
* Only run tests directly in __tests__
This lets us share code between test files by placing them in __tests__/utils.
* Remove ExecutionEnvironment dependency from DOMServerIntegrationTest
It's not necessary since Stack.
* Split up ReactDOMServerIntegration into test suite and utilities
This enables us to further split it down. Good both for parallelization and extracting public parts.
* Split Fragment tests from other DOMServerIntegration tests
This enables them to opt other DOMServerIntegration tests into bundle testing.
* Split ReactDOMServerIntegration into different test files
It was way too slow to run all these in sequence.
* Don't reset the cache twice in DOMServerIntegration tests
We used to do this to simulate testing separate bundles.
But now we actually *do* test bundles. So there is no need for this, as it makes tests slower.
* Rename test-bundles* commands to test-build*
Also add test-prod-build as alias for test-build-prod because I keep messing them up.
* Use regenerator polyfill for react-noop
This fixes other issues and finally lets us run ReactNoop tests against a prod bundle.
* Run most Incremental tests against bundles
Now that GCC generator issue is fixed, we can do this.
I split ErrorLogging test separately because it does mocking. Other error handling tests don't need it.
* Update sizes
* Fix ReactMount test
* Enable ReactDOMComponent test
* Fix a warning issue uncovered by flat bundle testing
With flat bundles, we couldn't produce a good warning for <div onclick={}> on SSR
because it doesn't use the event system. However the issue was not visible in normal
Jest runs because the event plugins have been injected by the time the test ran.
To solve this, I am explicitly passing whether event system is available as an argument
to the hook. This makes the behavior consistent between source and bundle tests. Then
I change the tests to document the actual logic and _attempt_ to show a nice message
(e.g. we know for sure `onclick` is a bad event but we don't know the right name for it
on the server so we just say a generic message about camelCase naming convention).
