Not processing correctly when using es2015 modules

Relates to #99

When using es2015 modules (necessary for example for tree-shaking), ts-jest throws an error not recognizing import statement. Such configuration can be:

{
    "compilerOptions": {
        "moduleResolution": "node",
        "target": "es6",
...

But when you use commonjs modules, it works

{
    "compilerOptions": {
        "module": "commonjs"
        "moduleResolution": "node",
        "target": "es6",
...

How to reproduce

git clone -b ts-jest-issue https://github.com/alexjoverm/typescript-library-starter.git
cd typescript-library-starter

npm install # give it the name "library" when asked
npm t

It will throw a SyntaxError: Unexpected token import

Now go to tsconfig.json and add "module": "commonjs" to the compilerOptions property. Execute npm t -- --no-cache

Then it works

[alexjoverm]

Ok, understood. I think I’ve done it in jest but you need babel-jest and all that stuff if I remember correctly.

If that’s the case, probably is better to add it to https://github.com/kulshekhar/ts-jest#known-limitations-for-ts-compiler-options?? Then other people don’t stumble into the same issue

[piotrwitek]

@kulshekhar @alexjoverm isn’t this commit introduced a regression to related PR #123? https://github.com/kulshekhar/ts-jest/commit/d26dbf6ff0b10a1a30f74274caef67e55d43bc29#diff-e1495d267619047a7cca5cfe8f692729L85

I have the same issue as OP, from what I understood the change was suppose to always override module entry, no matter if tsconfig is loaded from root folder or other folder like src/ in my case. I think the change from the commit changed to work only for tsconfig loaded from root folder. This change has broken my test config after the update.

My config:

// jest
{
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js"
  ],
  "transform": {
    ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
  },
  "globals": {
    "__TS_CONFIG__": "<rootDir>/src/tsconfig.json"
  }
}

//tsconfig
{
  "compilerOptions": {
    "target": "es5",
    "module": "es2015",
    "moduleResolution": "node",
    ...
  }
}

I have created a new issue to track this: https://github.com/kulshekhar/ts-jest/issues/161