tsconfig.spec.ts fails in MacOS, because /var is actually located in /private/var

I think having something like `fs.realpathSync` will solve the issue. I will test this and create a pull request later today.

```
  expect(received).toBe(expected) // Object.is equality

    Expected: "/var/folders/l1/q852l81d1lv95zhblgdvf0gr0000gn/T/tstl-test-FXslwE/tsconfig.json"
    Received: "/private/var/folders/l1/q852l81d1lv95zhblgdvf0gr0000gn/T/tstl-test-FXslwE/tsconfig.js
```