Include node_module of containing folders in the automatic @types discovery

[mhegazy]

c:\test>tree /f
│   package.json
│
├───node_modules
│   └───@types
│       └───node
│
└───src
        index.ts
        tsconfig.json

c:\test>cd src

c:\test\src>type index.ts
import * as fs from "fs";

c:\test\src>npm install @types/node
test@1.0.0 c:\test
`-- @types/node@6.0.38

c:\test\src>tsc
index.ts(1,21): error TS2307: Cannot find module 'fs'.

The issue here is that we only including node_modules in the current folder for automatic type discovery. this causes a lot of confusion for users trying to use the new @types package, specially if they are global. ppl do not usually associate the location of their tsconfig.json with it not working, all they see is that sometimes it does and sometimes it does not.

[yortus]

Worth noting that TypeScript already searches up through containing folders for typings that are bundled into their modules, i.e. modules whose package.json uses the "typings" field.

And of course the runtime behaviour with node_modules is to search up through containing folders too.

For example the following very similar example works. The difference is that the @cycle/dom module bundles its own typings. In this case TypeScript does search containing directories.

c:\test>tree /f
│   package.json
│
├───node_modules
│   └───@cycle
│       └───dom
│
└───src
        index.ts
        tsconfig.json

c:\test>cd src

c:\test\src>type index.ts
import * as dom from "@cycle/dom";

c:\test\src>npm install @cycle/dom xstream
test@1.0.0 c:\test
+-- @cycle/dom@12.2.2
`-- xstream@6.2.0

c:\test\src>tsc