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Undici mocking won't intercept my request in a jest test

I am trying to upgrade my node project to use version 18 and the built in fetch vs our old method of using node-fetch. We were writing tests using nock, which isn't an option with this version of fetch. I am not able to get undici to intercept the request. I am getting the response as if I went to the page (google.com/test)
I created a standalone test file and that didn't work either.
const { MockAgent, setGlobalDispatcher, } = require('undici');
test('should respond with body passed in', async () => {
const opts = { method: 'GET' };
const body = { statusInfo: { status: 'SUCCESS' }};
const agent = new MockAgent({ connections: 1 });
agent.get('http://www.google.com').intercept({
path: '/test'
}).reply(200, body);
agent.disableNetConnect();
agent.activate();
setGlobalDispatcher(agent);
const result = await fetch('http://www.google.com/test', opts);
console.log(JSON.stringify(result));
// console.log('%o', result);
console.log(await result.text());
// expect(result).toEqual(body);
});

Unit test a custom authorizer lambda

I have a customized authorizer lambda which takes an event from a API Gateway and calls another internal api which validates if a user has access to a particular resource.
This API takes in a jwttoken and a id and returns back response.
I have been trying to write unit test for this lambda. I am lost as to how can I mock data - specifically the token and id.
Here is what I wrote (Jest)
describe('lambdaService', () => {
beforeEach(() => {
jest.restoreAllMocks();
});
test('should return data', async () => {
const response = { statusCode: 200 };
const event = {
"headers" : {
'Authorization' : 'token'
},
"pathParameters": {
"proxy": "/my-path/{id}"
},
}
const retrieveData = jest.spyOn(authorizeResourceJWTUser, 'doGetRequest').mockResolvedValueOnce(response)
const actualValue = await handler(event);
expect(actualValue).toEqual(response);
});
const {validate} = require('./helper/validateResource')
exports.handler = async (event, context, callback) => {
try {
let id, token, HOST
id = extractId(path)//some function to return id from url
let response = await validate(id, token)
callback(null,generatePolicy(...)
} catch(error) {
callback("Unauthorized")
}
};
function generatePolicy {...};
But it fails giving 401 error since the token and the {id} is not valid.
There is no proper documentation on how can I mock this API call rather than calling the actual service

Remix: middleware pattern to run code before loader on every request?

Is there a recommended pattern in Remix for running common code on every request, and potentially adding context data to the request? Like a middleware? A usecase for this might be to do logging or auth, for example.
The one thing I've seen that seems similar to this is loader context via the getLoadContext API. This lets you populate a context object which is passed as an arg to all route loaders.
It does work, and initially seems like the way to do this, but the docs for it say...
It's a way to bridge the gap between the adapter's request/response API with your Remix app
This API is an escape hatch, it’s uncommon to need it
...which makes me think otherwise, because
This API is explicitly for custom integrations with the server runtime. But it doesn't seem like middlewares should be specific to the server runtime - they should just be part of the 'application' level as a Remix feature.
Running middlewares is a pretty common pattern in web frameworks!
So, does Remix have any better pattern for middleware that runs before every loader?

Instead of middleware, you can call a function directly inside the loader, this will also be more explicit. If you want to early return a response from those "middlewares" Remix let you throw the response object.
For example, if you wanted to check the user has a certain role you could create this function:
async function verifyUserRole(request: Request, expectedRole: string) {
let user = await getAuthenticatedUser(request); // somehow get the user
if (user.role === expectedRole) return user;
throw json({ message: "Forbidden" }, { status: 403 });
}
And in any loader call it this way:
let loader: LoaderFunction = async ({ request }) => {
let user = await verifyUserRole(request, "admin");
// code here will only run if user is an admin
// and you'll also get the user object at the same time
};
Another example could be to require HTTPS
function requireHTTPS(request: Request) {
let url = new URL(request.url);
if (url.protocol === "https:") return;
url.protocol = "https:";
throw redirect(url.toString());
}
let loader: LoaderFunction = async ({ request }) => {
await requireHTTPS(request);
// run your loader (or action) code here
};

There is no way inside Remix to run code before loaders.
As you found out, there is the loader context but it runs even before remix starts to do its job (so you won't know which route modules are matched for example).
You can also run arbitrary code before handing the request to remix in the JS file where you use the adapter for the platform you're deploying to (this depend on the starter you used. This file doesn't exist if you've chosen remix server as your server)
For now it should work for some use cases, but I agree this is a missing feature in remix for now.

Inside app/root.tsx
export let loader: LoaderFunction = ({ request }) => {
const url = new URL(request.url);
const hostname = url.hostname;
const proto = request.headers.get("X-Forwarded-Proto") ?? url.protocol;
url.host =
request.headers.get("X-Forwarded-Host") ??
request.headers.get("host") ??
url.host;
url.protocol = "https:";
if (proto === "http" && hostname !== "localhost") {
return redirect(url.toString(), {
headers: {
"X-Forwarded-Proto": "https",
},
});
}
return {};
};
Source: https://github.com/remix-run/remix-jokes/blob/8f786d9d7fa7ea62203e87c1e0bdaa9bda3b28af/app/root.tsx#L25-L46

here is my middlewares implementation for remix with typescript,it's works well
ctx.return(something)=== useLoaderData()
import compose from '#utils/compose';
export default function Index() {
const ctx = useLoaderData();
return <div>{ctx.name}</div>;
}
type DefaultCtx = {
name: string;
} & Request;
export const loader =(...args)=>compose<DefaultCtx>(
async (ctx, next) => {
ctx.name = 'first';
await next();
},
async (ctx, next) => {
ctx.name = 'secnod';
await next();
},
async (ctx, next) => {
ctx.name = 'third';
ctx.return(ctx);
await next();
}
)(args);
compose is same as koa;
here is the compose's implementation
type Next = () => Promise<void>;
type Context = {};
type Middle<T = {}> = (ctx: Context & T, next: Next) => void;
const compose = <T>(...middlewares: Middle<T>[]) => {
return middlewares.reverse().reduce(
(dispatch, middleware) => {
return async ctx =>
middleware(ctx, async () => dispatch(ctx, async () => {}));
},
async () => {}
);
};
export type Middleware<T = {}, P = unknown> = (
ctx: Context & T & { return: (param: P) => void },
next: Next
) => void;
const returnEarly: Middleware = async (ctx, next) => {
return new Promise<any>(async resolve => {
ctx.return = resolve;
await next();
});
};
const componseWithReturn = <T>(...middlewares: Middleware<T>[]) =>
compose(returnEarly, ...middlewares) as (ctx: T) => void;
export default componseWithReturn;

Stubbing request across entire project

I'm writing tests for a small REST library that implements OAuth's refresh grant on top of the request library. As part of it's functionality, it's providing a retry function that has something like this in rest.js:
const auth = require('./auth');
const request = require('request');
function retry(headers, responseHandler) {
headers.auth.bearer = auth.getToken();
request(headers, function(err, resp) {
if (resp.error && resp.error == 'invalid_token') {
return auth.renew(function(e, r) { retry(headers, responseHandler); });
}
// handle happy case
});
});
What auth.renew does is posting to the token provider with the information in headers and internally known refresh token. The important bit is that it does this by using request.post, passing the recursive event handler down to the request library.
Naturally, when I test this, I don't want outgoing HTTP calls. So I use sinon to stub them out:
const requestStub = sinon.stub(),
rest = proxyquire('./rest', { 'request': requestStub }),
authFail = { error: 'invalid_token' },
authSuccess = { token: '123' };
describe('#retry', () => {
it('calls retry twice on failed auth', () => {
requestStub.yields(null, authFail);
requestStub.post = sinon.stub().yields(null, authSuccess);
retry({}, () => {});
sinon.assert.calledTwice(requestStub);
});
});
The problem is that auth.renew happily goes on to require('request') on it's own and thus never seeing my stub. So I guess my question is:
How do I make auth use my stubbed request instead of its own?
I know sinon can stub XHR, but that seems like a lot of low-level effort for what I want.

So the solution I came up with was to replace the entire auth.renew method, so the thing looks like this:
const requestStub = sinon.stub(),
rest = proxyquire('./rest', { 'request': requestStub,
'./auth': {
renew: function(callback) {
requestStub.yields(null, authSuccess);
callback();
}
}),
authFail = { error: 'invalid_token' },
authSuccess = { token: '123' };
describe('#retry', () => {
it('calls retry twice on failed auth', () => {
requestStub.yields(null, authFail);
retry({}, () => {});
sinon.assert.calledTwice(requestStub);
});
});

How to mock es6 class using Jest

I am attempting to mock a class Mailer using jest and I can't figure out how to do it. The docs don't give many examples of how this works. The process is the I will have a node event password-reset that is fired and when that event is fired, I want to send an email using Mailer.send(to, subject, body). Here is my directory structure:
project_root
-- __test__
---- server
------ services
-------- emails
---------- mailer.test.js
-- server
---- services
------ emails
-------- mailer.js
-------- __mocks__
---------- mailer.js
Here is my mock file __mocks__/mailer.js:
const Mailer = jest.genMockFromModule('Mailer');
function send(to, subject, body) {
return { to, subject, body };
}
module.exports = Mailer;
and my mailer.test.js
const EventEmitter = require('events');
const Mailer = jest.mock('../../../../server/services/emails/mailer');
test('sends an email when the password-reset event is fired', () => {
const send = Mailer.send();
const event = new EventEmitter();
event.emit('password-reset');
expect(send).toHaveBeenCalled();
});
and finally my mailer.js class:
class Mailer {
constructor() {
this.mailgun = require('mailgun-js')({
apiKey: process.env.MAILGUN_API_KEY,
domain: process.env.MAILGUN_DOMAIN,
});
}
send(to, subject, body) {
return new Promise((reject, resolve) => {
this.mailgun.messages().send({
from: 'Securely App <friendly-robot#securelyapp.com>',
to,
subject: subject,
html: body,
}, (error, body) => {
if (error) {
return reject(error);
}
return resolve('The email was sent successfully!');
});
});
}
}
module.exports = new Mailer();
So, how do I successfully mock and test this class, using Jest? Many thanks for helping!

You don't have to mock your mailer class but the mailgun-js module. So mailgun is a function that returns the function messages that return the function send. So the mock will look like this.
for the happy path
const happyPath = () => ({
messages: () => ({
send: (args, callback) => callback()
})
})
for the error case
const errorCase = () => ({
messages: () => ({
send: (args, callback) => callback('someError')
})
})
as you have this 2 cases it make sense to mock the module inside your test. First you have to mock it with a simple spy where we later can set the implementation for our cases and then we have to import the module.
jest.mock('mailgun-js', jest.fn())
import mailgun from 'mailgun-js'
import Mailer from '../../../../server/services/emails/mailer'
As your module uses promises we have 2 options either return the promise from the test or use async/await. I use the later one for more info have a look here.
test('test the happy path', async() => {
//mock the mailgun so it returns our happy path mock
mailgun.mockImplementation(() => happyPath)
//we need to use async/awit here to let jest recognize the promise
const send = await Mailer.send();
expect(send).toBe('The email was sent successfully!')
});
If you would like to test that the mailgun send method was called with the correct parameter you need to adapt the mock like this:
const send = jest.fn((args, callback) => callback())
const happyPath = () => ({
messages: () => ({
send: send
})
})
Now you could check that the first parameter for send was correct:
expect(send.mock.calls[0][0]).toMatchSnapshot()

Just for Googlers and future visitors, here's how I've setup jest mocking for ES6 classes.
I also have a working example at github, with babel-jest for transpiling the ES module syntax so that jest can mock them properly.
__mocks__/MockedClass.js
const stub = {
someMethod: jest.fn(),
someAttribute: true
}
module.exports = () => stub;
Your code can call this with new, and in your tests you can call the function and overwrite any default implementation.
example.spec.js
const mockedClass = require("path/to/MockedClass")();
const AnotherClass = require("path/to/AnotherClass");
let anotherClass;
jest.mock("path/to/MockedClass");
describe("AnotherClass", () => {
beforeEach(() => {
mockedClass.someMethod.mockImplementation(() => {
return { "foo": "bar" };
});
anotherClass = new AnotherClass();
});
describe("on init", () => {
beforeEach(() => {
anotherClass.init();
});
it("uses a mock", () => {
expect(mockedClass.someMethod.toHaveBeenCalled();
expect(anotherClass.settings)
.toEqual(expect.objectContaining({ "foo": "bar" }));
});
});
});