"Protocol "http:" not supported. Expected "https:"" when using superagent

Describe the bug

When I try to use msw alongside superagent in Node, it throws an error:

UnhandledPromiseRejectionWarning: TypeError [ERR_INVALID_PROTOCOL]: Protocol "http:" not supported. Expected "https:"

(I’m aware of issues such as https://github.com/mswjs/msw/issues/209 but this one seems to be different)

Environment

• msw: 0.27.0
• nodejs: 12.14.0
• npm: 0.0.0

Please also provide your browser version. n/a

To Reproduce

Clone the repository on https://github.com/tomdohnal/msw-superagent-repro or run this piece of code using node

const { rest } = require("msw");
const { setupServer } = require("msw/node");
const request = require("superagent");
const fetch = require("node-fetch");

setupServer(
  rest.get("https://google.com", (req, res, ctx) => {
    return res(ctx.status(200), ctx.text("Hi from google"));
  })
).listen();

request.get("https://google.com").end(); // -> throws an error

// fetch("https://google.com")
//   .then((res) => res.text())
//   .then(console.log); -> works just fine

Expected behavior

No error should be thrown and the call should be mocked

Screenshots

n/a

[kettanaito]

This should get published in the next version (#660).

[tomdohnal]

OK so I did some debugging and found out that the problem is caused by the fact that when superagent (the HTTP(S) client) makes an HTTPS request, it doesn’t pass a protocol property to the request options.

As per https://nodejs.org/api/https.html#https_https_request_options_callback the default value of the protocol option passed to the https.request call is (not surprisingly 😄) https so there is no need to be explicit about it.

However, as the normalizeHttpRequestParams only accept the request options object as an argument (and doesn’t accept the info about if the request is being made using the http or https module), it falls back to creating a URL beginning with http which then causes an error to be thrown in the msw library.

One possible solution that comes to my mind would be to propagate the protocol variable all the way from the handleRequestFunction (in src/interceptors/ClientRequest/index.ts) to the normalizeHttpRequestParams function and use the protocol variable to put together the correct URL (if there is no protocol variable on the request options object).

I’m happy to send a PR with the fix but first I wanted to discuss how to approach this 🙂