fix: do not require ts-jest and typescript

[lmiller1990]

We can use the tsconfig module to see if a tsconfig.json exists. If it doesn't, we can assume they are not using TypeScript. This removes the need to install TS for non TS projects.

[boboldehampsink]

@lmiller1990 Time for a release? ;-)

[lmiller1990]

I can do one, was hoping to look at #309 first, since we currently assume tsconfig.json is at the root dir, which is not always the case.

At the moment you just need to install ts-jest to work-around, is this blocking you?

Either way we can probably do a release in the next day or two.

[williamweckl]

@lmiller1990 I see that the other issue you pointed to is already solved. Could you release a new version with the both fixes?

Thank you! :)

[lmiller1990]

Ok I will do it this week

[lmiller1990]

It's out https://github.com/vuejs/vue-jest/releases/tag/v5.0.0-alpha.8

Very tiny release. I hope I can dedicate some time soon to fixing the many TS problems we have. I think it should not be too difficult.

[xiaohulu]

Should support tsconfig not place at root dir.
If run npm run jest, process.cwd() always be root dir. I put tsconfig file at <rootDir>/sub.

[lmiller1990]

Yes, this is a problem. We should support something like

// jest.config.js
module.exports = {  
  globals: {
    'vue-jest': {
      tsconfig: './some/path/tsconfig.json'
    }
  }
}

Would you like to make a PR? I can review + release when it's done. If I need to do it, it might take a while, I have a few other projects I need to work on like Test Utils 2.0.0 release etc. I'd really appreciate the help!