There are a lot of tools out there that do the full-fledged mock (for testing, but I still decide to provide an alternative because

  1. Instead of mocking slack client, I mock HTTP
  2. I only need a (very) few test cases, and I want something very lightweight.
  1. mock the server
  2. create a service that will consume the api-client ( slack-go )
  3. write test

1. Mock The Server