In test.ts of John Papa's Angular Tour of Heroes demo project, there are the following imports:
import 'zone.js/dist/long-stack-trace-zone';
import 'zone.js/dist/proxy.js';
import 'zone.js/dist/sync-test';
import 'zone.js/dist/jasmine-patch';
import 'zone.js/dist/async-test';
import 'zone.js/dist/fake-async-test';
These files aren't in the src directory of the app, though. They become available in node_modules when you npm install the packages defined in package.json. My question is: How does Typescript/Angular know how to interpret these imports? I mean importing modules in general, not specific to only this packge. The question merely came up as I'm setting up a testing suite.