How can I specify multiple source folders in my tsconfig.json? - unit-testing

Question

I currently have the following project structure:
project/
tsconfig.json
webpack.config.js
package.json
node_modules/
...lots of dependencies
typings/
...lots of .d.ts files for the dependencies
src/
...folders for files for my projects
My tsonfig.json looks like:
{
"compilerOptions": {
"module": "commonjs",
"target": "es5",
"noImplicitAny": false,
"outDir": "./js",
"rootDir": "./src",
"sourceMap": true,
"jsx": "react"
},
"exclude": [
"typings/main.d.ts",
"typings/main",
"node_modules"
]
}
This all works very well and I can happily develop my application and run it in a browser.
I would now like to add some unit tests to my project and coming from a Java background my initial instinct is to place the tests in a separate folder:
project/
test/
...all of my test cases
Of course, the files in the test/ folder need to reference the code in my src/ folder. How do I set that up?
Or is it "better" to place the tests inline in the src/ folder and have a separate webpack.config.js file for them?
Really confused about how this works in practice in larger TypeScript projects.
Note: I have seen this but found the answer less than illuminating. It seems that the referenced feature discussion about filesGlob would help me, but I just wonder how people are doing this today?

Answer 1

Now other than rootDir, you can use rootDirs
"rootDirs": ["./scripts", "./src"],
for multiple folders.
Here is the API doc: https://www.typescriptlang.org/docs/handbook/module-resolution.html#virtual-directories-with-rootdirs

Answer 2

I think you are looking for path mapping. With the paths compiler option, you can specify not only a mapping to a single location but to several. This is the example from the documentation:
"compilerOptions": {
"baseUrl": ".",
"paths": {
"*": [
"*",
"generated/*"
]
}
}
If the compiler does not find a module in the expected location, it repeats module resolution in the "generated" subfolder. The baseUrl setting seems redundant but it is mandatory.

Answer 3

Or is it "better" to place the tests inline in the src/ folder and have a separate webpack.config.js file for them?
That is what I do. Do not use the TypeScript compiler as a module bundler (Especially if you are not using modules https://github.com/TypeStrong/atom-typescript/blob/master/docs/out.md). Just let it do the compile and bundle for browser using webpack and use as it is (if using module commonjs) for backend (nodejs).