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How to provide test ESModule implementation in mocha test?

I have a mocha test which tests my code. My code uses another "core" npm package (which uses CommonJS modules). One of "core" the files ("synchronizer.js" file) requires "prefs" modules which is assumed to be provided at some point:
const {Prefs} = require("prefs");
In the mocha test i'd like to implement this "prefs" module, so i've created "prefs.mjs" file (with exports that "synchronizer.js" expects). However during the test i have the following error:
Error: Cannot find module 'prefs'
Require stack:
- /Users/developer/Documents/dev/src/project/node_modules/core/lib/synchronizer.js
- /Users/developer/Documents/dev/src/project/node_modules/core/lib/index.js
at Module._resolveFilename (node:internal/modules/cjs/loader:1026:15)
at Module._load (node:internal/modules/cjs/loader:872:27)
at Module.require (node:internal/modules/cjs/loader:1092:19)
at require (node:internal/modules/cjs/helpers:103:18)
at Object.<anonymous> (/Users/developer/Documents/dev/src/project/node_modules/core/lib/synchronizer.js:26:17)
at Module._compile (node:internal/modules/cjs/loader:1205:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1259:10)
at Module.load (node:internal/modules/cjs/loader:1068:32)
at Module._load (node:internal/modules/cjs/loader:909:12)
at Module.require (node:internal/modules/cjs/loader:1092:19)
at require (node:internal/modules/cjs/helpers:103:18)
at Object.<anonymous> (/Users/developer/Documents/dev/src/project/node_modules/core/lib/index.js:33:24)
at Module._compile (node:internal/modules/cjs/loader:1205:14)
at Module._extensions..js (node:internal/modules/cjs/loader:1259:10)
at Module.load (node:internal/modules/cjs/loader:1068:32)
at Module._load (node:internal/modules/cjs/loader:909:12)
at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:169:29)
at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
My project structure:
\sdk
\test
\unit
\ prefs
\prefs.mjs
\test.js
I run the tests (package.json):
"dependencies": {
...
"core": "^0.10.1",
...
},
"scripts": {
...
"unittest": "mocha --recursive ./test/unit/*.js",
...
}
}
test.js looks as follows:
describe("Section1", function() {
beforeEach(async function() {
await configureTestEnv();
// TODO: set "prefs" module
// TODO: set "io" module
// TODO: set "info" module
});
describe("subscriptions", function() {
it("throws if no condition is achieved", async function() {
...
I can run the tests (which does not include "core") successfully, so the testing works in general.
I suspect i have to use smth like webpack or babel, but i'd like to keep it clean and not using any deps or intermediate build steps if possible.
Should i pass modules directories paths to mocha to let node.js somehow find it?

Ended up using webpack and generating a module with aliased modules including prefs.

anchor test command error - Error: Cannot find module '[#project-serum/anchor] ' Please verify that the package.json has a valid "main" entry

I was following an introduction tutorial using anchor (solana framework), it is based in the official github.
In the testing part, I used anchor test command and I got this error:
BPF SDK: /home/sebastian/.local/share/solana/install/releases/1.9.12/solana-release/bin/sdk/bpf
cargo-build-bpf child: rustup toolchain list -v
cargo-build-bpf child: cargo +bpf build --target bpfel-unknown-unknown --release
Finished release [optimized] target(s) in 3.86s
cargo-build-bpf child: /home/sebastian/.local/share/solana/install/releases/1.9.12/solana-release/bin/sdk/bpf/dependencies/bpf-tools/llvm/bin/llvm-readelf --dyn-symbols /home/sebastian/Documentos/solana-project/anchor/examples/tutorial/basic-1/target/deploy/basic_1.so
To deploy this program:
$ solana program deploy /home/sebastian/Documentos/solana-project/anchor/examples/tutorial/basic-1/target/deploy/basic_1.so
The program address will default to this keypair (override with --program-id):
/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/basic-1/target/deploy/basic_1-keypair.json
yarn run v1.22.17
$ /home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/.bin/mocha -t 1000000 tests/
Error: Cannot find module '/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/#project-serum/anchor/dist/cjs/index.js'. Please verify that the package.json has a valid "main" entry
at tryPackage (node:internal/modules/cjs/loader:353:19)
at Function.Module._findPath (node:internal/modules/cjs/loader:566:18)
at Function.Module._resolveFilename (node:internal/modules/cjs/loader:919:27)
at Function.Module._load (node:internal/modules/cjs/loader:778:27)
at Module.require (node:internal/modules/cjs/loader:999:19)
at require (node:internal/modules/cjs/helpers:102:18)
at Object.<anonymous> (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/basic-1/tests/basic-1.js:2:16)
at Module._compile (node:internal/modules/cjs/loader:1099:14)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
at Module.load (node:internal/modules/cjs/loader:975:32)
at Function.Module._load (node:internal/modules/cjs/loader:822:12)
at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:170:29)
at ModuleJob.run (node:internal/modules/esm/module_job:198:25)
at async Promise.all (index 0)
at async ESMLoader.import (node:internal/modules/esm/loader:385:24)
at async importModuleDynamicallyWrapper (node:internal/vm/module:437:15)
at async formattedImport (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/mocha/lib/nodejs/esm-utils.js:7:14)
at async Object.exports.requireOrImport (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/mocha/lib/nodejs/esm-utils.js:48:32)
at async Object.exports.loadFilesAsync (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/mocha/lib/nodejs/esm-utils.js:88:20)
at async singleRun (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/mocha/lib/cli/run-helpers.js:125:3)
at async Object.exports.handler (/home/sebastian/Documentos/solana-project/anchor/examples/tutorial/node_modules/mocha/lib/cli/run.js:374:5)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
This is my package.json:
{
"name": "basic-1",
"version": "0.24.2",
"license": "(MIT OR Apache-2.0)",
"homepage": "https://github.com/project-serum/anchor#readme",
"bugs": {
"url": "https://github.com/project-serum/anchor/issues"
},
"repository": {
"type": "git",
"url": "https://github.com/project-serum/anchor.git"
},
"engines": {
"node": ">=11"
},
"scripts": {
"test": "anchor test --skip-lint"
},
"dependencies": {
"#project-serum/anchor": "^0.24.2"
}
}
I really appreciate any information about it. I also attach the tutorial and anchor's github link.
https://github.com/project-serum/anchor
https://youtu.be/CmG5_sIas1Q

Try re-installing #project-serum/anchor
yarn add #project-serum/anchor

In your anchor.toml file, try changing the value of 'test' to mocha tests/test.js , replace test.js with whatever the name of your file in tests.

Go check node_modules/#project-serum/anchor if you don't have a "dist" folder there you will have to run yarn add#project-serum/anchor again. When you can see that the "dist" folder was properly installed you'll be able to run your tests again.

TypeError: Cannot read property 'compile' of undefined

I'm currently trying to follow this tutorial for Ethereum Solidity coding, and for the following code:
const path = require('path');
const fs = require('fs'); // File system module
const solc = require('solc').default; // Solidity Compiler module
// Note that phrase resolving a link means to substitute the actual location in the file system for the symbolic link
// If we assume that logFile is a symbolic link to dir/logs/HomeLogFile, then resolving it yields dir/logs/HomeLogFile
// Generates a path that points directly to the inbox file. __dirname will be the root direction
// inboxPath = desktop/inbox/contracts/inbox.sol
const inboxPath = path.resolve(__dirname, 'contracts', 'inbox.sol');
// The next step is to actually read the contents of the source file now
// utf8 is the encoding to read the file's content
const source = fs.readFileSync(inboxPath, 'utf8');
// Call solc.compile and pass in our source code, with only 1 contract
// console.log() means put the output in the console
console.log(solc.compile(source, 1));
I get the following error when I hover over const solc = require('solc').default:
Could not find a declaration file for module 'solc'. 'c:/Users/Hana PC/Desktop/inbox/node_modules/solc/index.js' implicitly has an 'any' type.
Try `npm i --save-dev #types/solc` if it exists or add a new declaration (.d.ts) file containing `declare module 'solc';`ts(7016)
When I try node compile.js, I get:
C:\Users\Hana PC\Desktop\inbox\compile.js:18
console.log(solc.compile(source, 1));
^
TypeError: Cannot read property 'compile' of undefined
at Object.<anonymous> (C:\Users\Hana PC\Desktop\inbox\compile.js:18:18)
[90m at Module._compile (internal/modules/cjs/loader.js:1063:30)[39m
[90m at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)[39m
[90m at Module.load (internal/modules/cjs/loader.js:928:32)[39m
[90m at Function.Module._load (internal/modules/cjs/loader.js:769:14)[39m
[90m at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12)[39m
[90m at internal/main/run_main_module.js:17:47[39m
I've never used/interacted with TypeScript or JavaScript or anything of the sorts, so I honestly don't even know what this error means. I've already tried uninstalling and reinstalling solc multiple times, all to no avail.
My node.js version is:
6.14.8
I tried doing some searching online for what the implicitly has an 'any' type. means or how it could be fixed, but I honestly didn't get any of it. If it helps, my package.json looks like this:
{
"name": "inbox",
"version": "1.0.0",
"description": "",
"main": "compile.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "ISC",
"dependencies": {
"solc": "^0.8.0"
}
}
Any help is appreciated!
**** Update:**
Tried it with uninstall solc and a fresh install (without using version 0.4.17), and got an Assertion Error:
assert.js:383
throw err;
^
AssertionError [ERR_ASSERTION]: Invalid callback object specified.
at runWithCallbacks (C:\Users\Hana PC\Desktop\inbox\node_modules\[4msolc[24m\wrapper.js:97:7)
at compileStandard (C:\Users\Hana PC\Desktop\inbox\node_modules\[4msolc[24m\wrapper.js:207:14)
at Object.compileStandardWrapper [as compile] (C:\Users\Hana PC\Desktop\inbox\node_modules\[4msolc[24m\wrapper.js:214:14)
Wish I knew what was goin on

As per the discussion we had above, since the solidity file is using v0.4.17, you should use the same version of solc library in your code.
I have created a working example of your code here and the only two changes required were:
Making sure I use v0.4.17 of solc.
Import const solc = require("solc"); and not const solc = require("solc").default;
If you are having trouble downgrading the solc package, then
Delete package-lock.json file and node_modules/ folder.
Update the package.json files dependency to "solc": "0.4.17" and not to "^0.4.17"
Simply run npm install one last time.
This should be enough to get you up and running.

Node.js "Error: Can not find module"

I am doing the node.js lesson from lynda.com and am unable to find what is causing the "Error: Can not find module". From everything I can tell the package.json has the flight module in it.
Everything has been working so far so I know node.js is installed and running correctly. The way I am running this file is by typing "node app.js" at the command line. Also all of the files are in the same folder.
Here is the console log:
C:\Users\Jonathan\Desktop\flight>node app.js
module.js:340
throw err;
^
Error: Cannot find module './flight'
at Function.Module._resolveFilename (module.js:338:15)
at Function.Module._load (module.js:280:25)
at Module.require (module.js:364:17)
at require (module.js:380:17)
at Object.<anonymous> (C:\Users\Jonathan\Desktop\flight\app.js:1:76)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)
C:\Users\Jonathan\Desktop\flight>
Here is the code.
Package.json file
{
"name": "flight",
"version": "1.0.0",
"description": "a module for keeping track of a flight",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "JBaxter",
"license": "ISC"
}
index.js file
var number, origin, destination;
exports.setNumber = function (num){
number = num;
};
exports.setOrigin = function (o){
origin = o;
};
exports.setDestination = function (d){
destination = d;
};
exports.getInfo = function() {
return {
number: number,
origin: origin,
destination: destination
};
};
app.js file
var flight = require('./flight');
flight.setOrgin('LAX');
flight.setDestination('DCA');
flight.setNumber(462);
console.log(flight.getInfo());
Any help with be great. I thought the name within the package.json file was your module but maybe I am incorrect. Thanks in advance.

"./flight" does not evaluate to index.js in your case.
If you create a subdir :
flight
- index.js
then you can require("./flight") and have it evaluated to "./flight/index.js".
In your case, simplest thing you could to do :
require("./index.js");

you can do it in the following way:
var flight = require('./index.js');
OR
var flight = require('./index');
Following code will not work because the node will look for module named 'flight' in node_modules folder
var flight = require('flight');

Binary file in npm package

I try to create an npm package, which can be started as a command from shell. I have package.json
{
"name": "myapp",
"version": "0.0.6",
"dependencies": {
"async": "",
"watch": "",
"node-promise": "",
"rmdir": "",
"should": "",
"websocket": ""
},
"bin": "myapp"
}
and myapp
#!/bin/bash
path=`dirname "$0"`
file="/myapp.js"
node $path$file $1 &
But I get an error:
module.js:340
throw err;
^
Error: Cannot find module '/usr/local/bin/myapp.js'
at Function.Module._resolveFilename (module.js:338:15)
at Function.Module._load (module.js:280:25)
at Function.Module.runMain (module.js:497:10)
at startup (node.js:119:16)
at node.js:902:3
The problem is that myapp.js is in another directory. How can I get this directory name from my script? Or maybe there is better way to do this?

Actually, you can put your myapp.js file into bin.
So, the bin key in package.json file should be like this :
"bin": { "myapp" : "<relative_path_to_myapp.js>/lib/myapp.js" }
At the first line in myapp.js, you must add this shebang line :
#!/usr/bin/env node
It tells the system to use node to run myapp.js.
... Or if you don't want to call myapp.js directly, you can create a script like this to be your executable file :
#!/usr/bin/env node
var myapp = require('<relative_path_to_myapp.js>/myapp.js');
myapp.doSth();
and in package.json :
"bin" : { "myapp" : "<relative_path_to_the_script>/script.js" }
By doing this either way, you can avoid finding the path to your nodemodule.
But... if you insist to use your old myapp bash script, then you can find the path to the module with this :
myapp_path=$( npm explore -g myapp -- "pwd" )
Hope these help :D

https://docs.npmjs.com/files/package.json#bin
From the above link:
...
To use this, supply a bin field in your package.json which is a map of command name to local file name. On install, npm will symlink that file into prefix/bin for global installs, or ./node_modules/.bin/ for local installs.
For example, myapp could have this:
{ "bin" : { "myapp" : "./cli.js" } }
So, when you install myapp, it’ll create a symlink from the cli.js script to /usr/local/bin/myapp.
...