[test runner] Restore TEST_GREP support (jest's -t parameter)

[nicolo-ribaudo]

Q	A
License	MIT

Tested manually running yarn jest babel-parser/test/index -t placeholders and TEST_GREP=placeholders TEST_ONLY=babel-parser make test-only.

The logic is copied from https://github.com/facebook/jest/blob/3a85065fe5604655e1337ffc1631f9999722c821/packages/jest-circus/src/run.ts#L105 and https://github.com/facebook/jest/blob/e0b33b74b5afd738edc183858b5c34053cfc26dd/packages/jest-circus/src/eventHandler.ts#L237.

Thanks @pzuraq and @tolmasky for noticing that this stopped working! 😅

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/50787/

[tolmasky]

Nice! Thanks @nicolo-ribaudo

[JLHwung]

Another feature request for jest-light-runner: run in main thread when --runInBand is provided, mostly used for debugging.

[nicolo-ribaudo]

Do you still wish you had --runInBand? With the lighter wrappers that we use know, I have never felt the need for it.

[JLHwung]

Do you still wish you had --runInBand? With the lighter wrappers that we use know, I have never felt the need for it.

--runInBand is used for hooking debugger. Otherwise we have to pass --inspect-brk to each worker and figure out which worker is running the interested test. Currently I manually revise jest.config.js when I want to open a debugger.

[nicolo-ribaudo]

Oh ok, right. I didn't think about it because I take a different approach: using vscode (I don't remember which editor you use), I put a breakpoint in the test file (it works well because they are not compiled, but they are executed natively), and then I run that file with this .vscode/launch.json:

{
	"version": "0.2.0",
	"configurations": [
		{
			"type": "pwa-node",
			"request": "launch",
			"name": "Test current file",
			"program": "${workspaceFolder}/node_modules/.bin/jest",
			"args": ["${relativeFile}"]
		},
		{
			"type": "pwa-node",
			"request": "launch",
			"name": "Test current file (Babel 8)",
			"program": "${workspaceFolder}/node_modules/.bin/jest",
			"args": ["${relativeFile}"],
			"env": { "BABEL_8_BREAKING": "true" }
		}
	]
}