Cannot find name 'describe'. Do you need to install type definitions for a test runner?

ERROR in src/myApp/e2e/src/app.e2e-spec.ts(3,1): error TS2582: Cannot find name 'describe'. Do you need to install type definitions for a test runner? Try `npm i @types/jest` or `npm i @types/mocha`.

>>阅读原文<<