Add Create React App Section, clarify tradeoffs

[justgage]

Here's my second pass at the documentation for Create React App. A better version of #49 hopefully 😅

[coveralls]

Coverage remained the same at 97.978% when pulling fabecadf8dfeeb947188ae6ebb3bb3c3a39b6b3d on justgage:patch-2 into ad64578e005358382e4aa7957f0679e3293b2850 on glennsl:master.

[peterpme]

:wave: hey, I'm in the process of using create-react-app with bs-jest and i'd like to revisit/hash out issues i've personally faced.

i do agree with @glennsl's feedback - we include just the bare minimum required to get create-react-app working in this scenario.

Here are some of my high level questions:

Top level tests vs. src//tests**

To make sure we're on the same page, I have this in my bsconfig.json

{
  "dir": "__tests__",
  "type": "dev",
  "subdris": true
}

• If I don't include a top level __tests__ folder, bs yells at me
• If I don't put my tests in the top level __tests__ folder, open Jest can't be found.

Opinions aside, is this supposed to be the case? Do all my tests need to be in a top level test folder?

[glennsl]

Hi @peterpme :)

If I don't include a top level tests folder, bs yells at me

This seems like reasonable behaviour from bsb. It indicates there is a problem with your setup.

If I don't put my tests in the top level tests folder, open Jest can't be found.

I assume that's because you have bs-jest as a bs-dev-dependency, as you should, and the places you put your tests aren't in a source directory that has "type": "dev".

Do all my tests need to be in a top level test folder?

No, but they need to be in a folder marked as "type": "dev" in bsconfig.json. But from what I understand of CRA, they can't be in a top level folder because CRA runs jest in the src folder, not in the root folder. So I think you need something like this:

"sources": [{
  "dir": "src/app",
  "subdirs": true
}, {
  "dir": "src/__tests__",
  "type": "dev",
  "subdirs": true
}]

And then you have to put all the tests in src/__tests__.

It's also possible to have separate __tests__ folders alongside your app code, but then you ahve to turn off subdirs and list every folder explicitly in bsconfig.json, which is most likely not what you want.