I've investegated a way to mock HTTP request and response when writing a code to access to a HTTP API with http.Client. Finally, I found that I can do it by just implementing RoundTrip method of http.RoundTripper. Here is an example of mocking and proxying HTTP request and response. Running with go run main.go -mock mock, you can get mocked result and with go run main.go -mock proxy, you can get p