A configuration for using vim-projectionist with jest. I was looking for this but couldn't find it anywhere.

.projections.json

{
	"**/__tests__/*.js": {
		"alternate": "{}.js",
		"type": "test"
	},
	"*.js": {
		"alternate": "{dirname}/__tests__/{basename}.js",
		"type": "source"
	}
}

File extension must be 'json'

For my React Typescript code, where the convention was that tests were in a __tests__ folder and named X.test.tsx, I used the following

{
	"**/__tests__/*.test.tsx": {
		"alternate": "{}.tsx",
		"type": "test"
	},
	"*.tsx": {
		"alternate": "{dirname}/__tests__/{basename}.test.tsx",
		"type": "source"
	}
}