🏁 Journey of Unit testing

[ahmedsakr]

This issue will track wstrade-api's journey to becoming fully unit-tested with jest:

FIle	Status
src/accounts.js
src/auth.js
src/config.js	✔️
src/data.js
src/headers.js	✔️
src/core/cache.js	✔️
src/core/ticker.js	✔️
src/core/tokens.js	✔️
src/helpers/time.js	✔️
src/network/https.js
src/optional/securities-cache.js
src/orders.js
src/quotes/index.js