hardhat-starter-kit | boilerplate code for testing , deploying , and shipping | Blockchain library

to test locally you need to make use of mocks which can simulate having an oracle network. Because you're working locally, a Chainlink node doesn't know about your local blockchain, so you can't actually do proper VRF requests. Note you can try deploy a local Chainlink node and a local blockchain and have them talk, but it isn't fully supported yet so you may get mixed results. Anyway, as per the hardhat starter kit that you linked, you can set the defaultNetwork to be 'hardhat' in the hardhat.config.js file, then when you deploy and run the integration tests (yarn test-integration), it will use mocks to mock up the VRF node, and to test the requesting of a random number. See the test here, and the mock contracts and linktoken get deployed here