A couple of strategies can help with this - If you use fetch: this one's nice https://github.com/wheresrhys/fetch-mock https://github.com/wheresrhys/fetch-mock

A couple of strategies can help with this - If you use fetch: this one's nice https://github.com/wheresrhys/fetch-mock https://github.com/wheresrhys/fetch-mock - Define the API with https://swagger.io/ https://swagger.io/ - Contract testing (that's great if you have many consumers that rely on the API)