[devtools][tests] add support for @gate pragma

[gnoff]

Adds support for // @gate pragma in devtools tests
Adds a couple gate test assertions to ensure they continue to work

[react-sizebot]

Comparing: 01ab35a...c610e01

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	176.89 kB	176.89 kB	=	55.14 kB	55.14 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	179.00 kB	179.00 kB	=	55.80 kB	55.80 kB
facebook-www/ReactDOM-prod.classic.js	=	594.04 kB	594.04 kB	=	104.94 kB	104.94 kB
facebook-www/ReactDOM-prod.modern.js	=	577.33 kB	577.33 kB	=	101.96 kB	101.96 kB
test_utils/ReactAllWarnings.js	Deleted	66.40 kB	0.00 kB	Deleted	16.26 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
test_utils/ReactAllWarnings.js	Deleted	66.40 kB	0.00 kB	Deleted	16.26 kB	0.00 kB

Generated by 🚫 dangerJS against c610e01

[hoxyq]

Can you please check that this also works with @reactVersion annotation?

I am assuming that @gate annotation should be used only for DevTools tests against React from source, we could throw some error in other case

[gnoff]

@hoxyq would be happy too except I don't actually know how the devtools tests are set up to run against multiple versions. The gate pragma would ideally be used only from source (though my understanding is these tests still only run with the --build flag so it's from the current commit but built into real packages not loaded directly via require)

Is there some place we run devtools tests with older versions that is not part of the CI job that runs with each commit?

[hoxyq]

Is there some place we run devtools tests with older versions that is not part of the CI job that runs with each commit?

Yes, in

react/.circleci/config.yml

Lines 296 to 309 in 2f8f776

	run_devtools_tests_for_versions:
	docker: *docker
	environment: *environment
	parallelism: *TEST_PARALLELISM
	parameters:
	version:
	type: string
	steps:
	- checkout
	- attach_workspace:
	at: .
	- setup_node_modules
	- run: ./scripts/circleci/download_devtools_regression_build.js << parameters.version >> --replaceBuild
	- run: node ./scripts/jest/jest-cli.js --build --project devtools --release-channel=experimental --reactVersion << parameters.version >> --ci

This is ran daily.

This is where reactVersion pragma is evaluated for DevTools tests - https://github.com/facebook/react/blob/main/scripts/babel/transform-react-version-pragma.js

[gnoff]

merged and will run the pipeline manually. If it fails I'll revert