title: ReferenceError: describe is not defined in Jest + Typescript
body: <p>Simple configuration of Jest with ts-jest produces error "ReferenceError: describe is not defined" in runtime. Here minimal example: <a href="https://github.com/PFight/jest-ts-describe-not-defined-problem" rel="noreferrer">https://github.com/PFight/jest-ts-describe-not-defined-problem</a></p>
  
  <p>What I configured wrong?</p>