Read tsconfig content for jest ts-transform correctly

[andischerer]

Hi William,

thanks for your work on create-react-app on getting ts in there 👍.

I've ran into a bug in by using experimentaldecorators in tsconfig by running test and coverage scripts. Build and start tasks run fine while test runs fail with an ts-error related to decorators.
The jest ts-transform does not respect the tsconfig in my project root.

Looks like the method signature of readConfigFile had changed. Now there are 2 parameters required. I've added the missing fs-read parameter. Without this parameter, the tsconfig const is always empty and the default compilerOptions are used.
The content of the tsconfig file is now correctly read and the compilerOptions are getting respected in the ts-transform task.

[andischerer]

see definition: https://github.com/Microsoft/TypeScript/blob/v2.3.4/src/compiler/commandLineParser.ts#L869

[DorianGrey]

Oh, yeah, that's a result of an earlier PR of mine. Did not take the recent versions into consideration.

However, I'm afraid it takes a little more effort to get this working properly considering all potential circumstances.
A PR with the correct way to read the tsconfig.json already landed in ts-jest.
The relevant block starts here: https://github.com/kulshekhar/ts-jest/blob/master/src/utils.ts#L73

Just forgot to add a proper PR here as well - sorry for this inconvenience.

I'm wondering ... would there be any problem in using ts-jest instead of a custom transform solution (which aims at doing exactly the same)?

[wmonk]

I'm happy to move to ts-jest. Will it fix the issues found before? When I started this project i'm not sure ts-jest was working the way I wanted. But happy to move now!

[DorianGrey]

I've added a PR for further discussing the ts-jest topic (#100).

[wmonk]

Thanks for your work on this @andischerer, I believe using ts-jest is the way to go, so closing in favour of #100.