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Module not found when requiring library submodule in Jest tests

I am currently trying to write some tests for a node-based GCP Cloud Functions application.
At this point I've stripped it down to the bare minimum:
// index.js
const functions = require("#google-cloud/functions-framework");
const testing = require('#google-cloud/functions-framework/testing');
functions.http("updateProvider",
(req, res) => { res.send("OK"); });
My test file follows the sample here:
// index.spec.js
const {getFunction} = require('#google-cloud/functions-framework/testing');
require('../../');
describe("HelloTests", () => {
test("is testable", () => {
});
});
When I run jest I get the following error:
Cannot find module '#google-cloud/functions-framework/testing' from 'spec/unit/index.spec.js'
Some additional observations:
If I put that import statement into index.js and run the application, it imports just fine.
If I comment out the import statement from index.spec.js but leave it in index.js and run jest, I get the same error for the import in index.js.
This leads me to assume that Jest is not properly handling submodules. I've never worked with submodules like this before (that I can remember), so I'm at a complete loss. I did some digging and this is from the functions-framework node module's package.js:
"exports": {
".": {
"types": "./build/src/index.d.ts",
"default": "./build/src/index.js"
},
"./testing": {
"types": "./build/src/testing.d.ts",
"default": "./build/src/testing.js"
}
},
No idea if this is relevant but wanted to include it in case it's useful.
Any idea why I'm getting this error and/or how to resolve it without switching to ESM?
Update: I switched to ESM and get the exact same error.

This apparently got fixed earlier this year:
Issue: https://github.com/facebook/jest/issues/9771
Initial Release: https://github.com/facebook/jest/releases/tag/v28.0.0-alpha.3
I had copied an older (but still fairly recent!) package.json that was stuck on v27 so it wasn't picking up the latest library. Did a clean install and confirmed no further issue with at least v29.3.1.
Rookie mistake.

Next.js (React) - Can't import local typescript file into config file

Situation
I would like to run some Database code (mongoDB(mongoose)) on server startup / during builds. Considering next js doesn't have any lifecycle hooks that you can hook into in an easy manner, I was trying to perform the database actions in my webpack (next.config.mjs) configuration. However I ran into some problems with importing local files.
Current setup
This is the code of my current next.config.mjs file. (PS. I have also tried the CommonJS way of requiring the needed files, but that also fails with error meessage "module not found".)
None of the lines that import a local typescript file appear to succeed and I have checked the paths multiple times. They always end up with the error message "ERR_MODULE_NOT_FOUND". Only if a node_module package is imported, it works as expected (the mongoose npm package).
Code
/** #type {import('next').NextConfig} */
const { EmployeesSchema } = await import("./mongodb_schemas/employee_schema");
import { EmployeesSchema } from "./mongodb_schemas/employee_schema";
import "./util/test"
import mongoose from "mongoose";
const nextConfig = {
experimental: {
externalDir: true,
},
reactStrictMode: true,
swcMinify: true,
images: {
domains: ["*", "**", "www.google.com"],
},
webpack: (
config,
{ buildId, dev, isServer, defaultLoaders, nextRuntime, webpack }
) => {
if (isServer) {
console.log(process.cwd());
}
return config;
},
};
export default nextConfig;
Anyone got a clue to why this might end up happening / have any possible solutions to the problem? I have also tried with a normal JavaScript file instead of a Typescript file, which also didn't work. I have found some similar asked questions on Stack Overflow but which were all left unanswered.
My guess for the reason why this occurs: during the build of the project, so when "npm run dev" is ran, the next.config.mjs is copied to a different location into the file structure, which means that the relative paths aren't correct anymore and thus the files can't be found.
PS. My apologize if the question is unclear / in an unusual format, it is my first post so not used to it.

Change .page URL based on environment I need to run the suite in

We have been building our automation suite using our staging environment, but are going live soon and want to be ready to tell the project where to run (staging, production).
The only difference between the sites in the environments is the URL. My question is, from start to finish, how can I set the .page URL via a CLI option?
Right now, I have created an environment config file that holds our staging and production URLS and then I call the data into my test files. This is fine for now, but I will need to create a script with an option to set the environment at runtime without having to do a manual find and replace before kicking it off.
I've looked around online and find, what I believe, to be code snippets and general instructions, but I'm not a dev at heart and go crossed eyed. If I could get an ELI5 for this, that would be awesome.
Example of what I'm doing now:
const env = require('../environment_variables.json')
fixture `blog`
.page `${env.production}`
And then I change production to staging or vice versa manually before kicking off the suite.
Since the project will run from CICD, I would like to be able to do something like this in my CLI and script:
testcafe env=production
The env value will then be set where the .page call is for every test file.
Thanks!

There are different ways of doing this. I've used environment variables successfully in this situation, so I'll share this solution since it will solve your problem.
I create config.json in the root of the project:
{
"baseUrl": {
"dev": "https://dev.com/",
"staging": "https://staging.com/",
"prod": "https://prod.com/"
}
}
Then I create two helper functions somewhere like Helpers/env.js:
import config from '../config';
function getEnv () {
return process.env.TESTCAFE_ENV;
}
function getBaseUrl () {
return config.baseUrl[getEnv()];
}
export { getEnv, getBaseUrl };
Then in my test files in Tests/:
import { getBaseUrl } from '../Helpers/env';
const baseUrl = getBaseUrl();
fixture `Test Suite`
.page(baseUrl);
And that's it. Then when I need to run tests on the dev, I execute:
$ TESTCAFE_ENV=dev testcafe
for staging:
$ TESTCAFE_ENV=staging testcafe
and for production:
$ TESTCAFE_ENV=prod testcafe

In v1.20.0 and later, TestCafe offers a way to specify the baseUrl in the test run configuration. You can use this approach along with environment variables, see the following example:
.testcaferc.js
const BASE_URL_MAP = {
dev: 'https://dev.com/',
staging: 'https://staging.com/',
prod: 'https://prod.com/'
};
module.exports = {
baseUrl: BASE_URL_MAP[process.env.TESTCAFE_ENV]
};
Alternatively, you can use different configuration files for each of the required setups using the --config-file option.

react-testing-library why is toBeInTheDocument() not a function

Here is my code for a tooltip that toggles the CSS property display: block on MouseOver and on Mouse Out display: none.
it('should show and hide the message using onMouseOver and onMouseOut events respectively', () => {
const { queryByTestId, queryByText } = render(
<Tooltip id="test" message="test" />,
)
fireEvent.mouseOver(queryByTestId('tooltip'))
expect(queryByText('test')).toBeInTheDocument()
fireEvent.mouseOut(queryByTestId('tooltip'))
expect(queryByText('test')).not.toBeInTheDocument()
cleanup()
})
I keep getting the error TypeError: expect(...).toBeInTheDocument is not a function
Has anyone got any ideas why this is happening? My other tests to render and snapshot the component all work as expected. As do the queryByText and queryByTestId.

toBeInTheDocument is not part of RTL. You need to install jest-dom to enable it.
And then import it in your test files by:
import '#testing-library/jest-dom'

As mentioned by Giorgio, you need to install jest-dom. Here is what worked for me:
(I was using typescript)
npm i --save-dev #testing-library/jest-dom
Then add an import to your setupTests.ts
import '#testing-library/jest-dom/extend-expect';
Then in your jest.config.js you can load it via:
"setupFilesAfterEnv": [
"<rootDir>/src/setupTests.ts"
]

When you do npm i #testing-library/react make sure there is a setupTests.js file with the following statement in it
import '#testing-library/jest-dom/extend-expect';

Having tried all of the advice in this post and it still not working for me, I'd like to offer an alternative solution:
Install jest-dom:
npm i --save-dev #testing-library/jest-dom
Then create a setupTests.js file in the src directory (this bit is important! I had it in the root dir and this did not work...). In here, put:
import '#testing-library/jest-dom'
(or require(...) if that's your preference).
This worked for me :)

Some of the accepted answers were basically right but some may be slightly outdated:
Some references that are good for now:
https://github.com/testing-library/jest-dom
https://jestjs.io/docs/configuration
Here are the full things you need:
in the project's <rootDir> (aka where package.json and jest.config.js are), make sure you have a file called jest.config.js so that Jest can automatically pick it up for configuration. The file is in JS but is structured similarly to a package.json.
Make sure you input the following:
module.exports = {
testPathIgnorePatterns: ['<rootDir>/node_modules', '<rootDir>/dist'], // might want?
moduleNameMapper: {
'#components(.*)': '<rootDir>/src/components$1' // might want?
},
moduleDirectories: ['<rootDir>/node_modules', '<rootDir>/src'],
setupFilesAfterEnv: ['<rootDir>/src/jest-setup.ts'] // this is the KEY
// note it should be in the top level of the exported object.
};
Also, note that if you're using typescript you will need to make sure your jest-setup.ts file is compiled (so add it to src or to the list of items to compile in your tsconfig.json.
At the top of jest-setup.ts/js (or whatever you want to name this entrypoint) file: add import '#testing-library/jest-dom';.
You may also want to make sure it actually runs so put a console.log('hello, world!');. You also have the opportunity to add any global functions you'd like to have available in jest such as (global.fetch = jest.fn()).
Now you actually have to install #testing-library/jest-dom: npm i -D #testing-library/jest-dom in the console.
With those steps you should be ready to use jest-dom:
Without TS: you still need:
npm i -D #testing-library/jest-dom
Creating a jest.config.js and adding to it a minimum of: module.exports = { setupFilesAfterEnv: ['<rootDir>/[path-to-file]/jest-setup.js'] }.
Creating a [path-to-file]/jest-setup.js and adding to it: import '#testing-library/jest-dom';.
The jest-setup file is also a great place to configure tests like creating a special renderWithProvider( function or setting up global window functions.

None of the answers worked for me because I made the silly mistake of typing toBeInDocument() instead of toBeInTheDocument(). Maybe someone else did the same mistake :)

I had a hard time solving that problem so I believe it's important to note the followings if you're using CREATE REACT APP for your project:
You DO NOT need a jest.config.js file to solve this, so if you have that you can delete it.
You DO NOT need to change anything in package.json.
You HAVE TO name your jest setup file setupTests.js and have it under the src folder. It WILL NOT work if your setup file is called jest.setup.js or jest-setup.js.

install required packages
npm install --save-dev #testing-library/jest-dom eslint-plugin-jest-dom
create jest-setup.js in the root folder of your project and add
import '#testing-library/jest-dom'
in jest.config.js
setupFilesAfterEnv: ['<rootDir>/jest-setup.js']
TypeScript only, add the following to the tsconfig.json file. Also, change .js extension to .ts.
"include": ["./jest-setup.ts"]
toBeInTheDocument() and many similar functions are not part of the React-testing-library. It requires installing an additional package.

For anyone out there that like is trying to run tests in Typescript with jest and is still getting the same error even after installing #testing-library/jest-dom and following all the other answers: you probably need to install the type definitions for jest-dom (here) with:
npm i #types/testing-library__jest-dom
or
yarn add #types/testing-library__jest-dom
You need to install them as real dependencies and not as devDependency.

I was having this issue but for #testing-library/jasmine-dom rather than #testing-library/jest-dom.
The process of setup is just a tiny bit different with jasmine. You need to set up the environment in a before function in order for the matchers to be added. I think jest-dom will go ahead and add the matchers when you first import but Jasmine does not.
import { render, screen } from '#testing-library/react';
import MyComponent from './myComponent';
import JasmineDOM from '#testing-library/jasmine-dom';
describe("My Suite", function () {
beforeAll(() => {
jasmine.getEnv().addMatchers(JasmineDOM);
})
it('render my stuff', () => {
const { getByText } = render(<MyComponent />);
const ele = screen.getByText(/something/i);
expect(ele).toBeInTheDocument();
});
});

If you are using react-script then follow the below steps
Install #testing-library/jest-dom library if not done already using
npm i #testing-library/jest-dom.
Put import "#testing-library/jest-dom/extend-expect" in setUpTest.js
If you are using jest then import the library in jest.setup.js file.

the problem already was solved, but i will comment a little tip here, you don't need to create a single file called setup just for this, you just need to specify the module of the jest-dom on the setupFilesAfterEnv option in your jest configuration file.
Like this:
setupFilesAfterEnv: ['#testing-library/jest-dom/extend-expect'],

If you're using TS
You could also add a test.d.ts file to your test directory and use a triple slash directive:
///<reference types='#testing-library/jest-dom'>

Instead of doing:
expect(queryByText('test')).toBeInTheDocument()
you can find and test that it is in the document with just one line by using
let element = getByText('test');
The test will fail if the element isn't found with the getBy call.

How to properly require modules from mocha.opts file

I'm using the expect.js library with my mocha unit tests. Currently, I'm requiring the library on the first line of each file, like this:
var expect = require('expect.js');
describe('something', function () {
it('should pass', function () {
expect(true).to.be(true); // works
});
});
If possible, I'd like to remove the boilerplate require code from the first line of each file, and have my unit tests magically know about expect. I thought I might be able to do this using the mocha.opts file:
--require ./node_modules/expect.js/index.js
But now I get the following error when running my test:
ReferenceError: expect is not defined
This seems to make sense - how can it know that the reference to expect in my tests refers to what is exported by the expect.js library?
The expect library is definitely getting loaded, as if I change the path to something non-existent then mocha says:
"Error: Cannot find module './does-not-exist.js'"
Is there any way to accomplish what I want? I'm running my tests from a gulp task if perhaps that could help.

You are requiring the module properly but as you figured out, the symbols that the module export won't automatically find themselves into the global space. You can remedy this with your own helper module.
Create test/helper.js:
var expect = require("expect.js")
global.expect = expect;
and set your test/mocha.opts to:
--require test/helper

While Louis's answer is spot on, in the end I solved this with a different approach by using karma and the karma-chai plugin:
Install:
npm install karma-chai --save-dev
Configure:
karma.set({
frameworks: ['mocha', 'chai']
// ...
});
Use:
describe('something', function () {
it('should pass', function () {
expect(true).to.be(true); // works
});
});

Thanks to Louis answer and a bit of fiddling around I sorted out my test environment references using mocha.opts. Here is the complete setup.
My project is a legacy JavaScript application with a lot of "plain" js files which I wish to reference both in an html file using script tags and using require for unit testing with mocha.
I am not certain that this is good practice but I am used to Mocha for unit testing in node project and was eager to use the same tool with minimal adaptation.
I found that exporting is easy:
class Foo{...}
class Bar{...}
if (typeof module !== 'undefined') module.exports = { Foo, Bar };
or
class Buzz{...}
if (typeof module !== 'undefined') module.exports = Buzz;
However, trying to use require in all the files was an issue as the browser would complain about variables being already declared even when enclosed in an if block such as:
if (typeof require !== 'undefined') {
var {Foo,Bar} = require('./foobar.js');
}
So I got rid of the require part in the files and set up a mocha.opts file in my test folder with this content. The paths are relative to the root folder:
--require test/mocha.opts.js
mocha.opts.js content. The paths are relative to the location of the file:
global.assert = require('assert');
global.Foo = require("../foobar.js").Foo;
global.Bar = require("../foobar.js").Bar;
global.Buzz = require("../buzz.js");