Error - Can't find Jest - Describe , It ect - node.js

Question

I had this problem going on for weeks and today I decided to investigate this matter. What I have noticed is that if I create a brand new project and install #types/jest, jest, supertest and just make a test folder with a dummy test file like dummy.test.js, I'm able to get describe, it ect ect.
when I compare this package.json file with my microservices package.json file, the only difference is that I have few dependencies in my microservices package.json.
here you can see the difference:
new node project
{
"name": "jest",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "NODE_ENV=test jest --watchAll --verbose --coverage"
},
"author": "",
"license": "ISC",
"devDependencies": {
"#types/jest": "^27.4.1",
"jest": "^27.5.1",
"supertest": "^6.2.2"
}
}
and this is my microservices package.json file:
{
"name": "auth",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"start": "NODE_ENV=development nodemon src/index.js -watch",
"test": "NODE_ENV=test jest --watchAll --verbose --coverage"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"bcrypt": "^5.0.1",
"config": "^3.3.6",
"cookie-parser": "^1.4.6",
"cors": "^2.8.5",
"dotenv": "^16.0.0",
"express": "^4.17.3",
"express-async-errors": "^3.1.1",
"helmet": "^3.21.1",
"http-status-codes": "^2.2.0",
"joi": "^17.6.0",
"jsonwebtoken": "^8.5.1",
"lodash": "^4.17.21",
"moment": "^2.29.2",
"mongoose": "^6.2.10"
},
"devDependencies": {
"#types/jest": "^27.4.1",
"jest": "^27.5.1",
"supertest": "^6.2.2"
}
}
Honestly I'm not understanding what is going on here!
In my new project, I don't need to configure a tsconfig.json for this matter, so I don't see the logic with this problem.
I would appreciate any explanation and maybe with an example to this matter so I can understand why can't see jest properties in my microservices project and in my new project the properties appears without any problems.

Answer 1

After searching what is tsconfig.json and what it does, I finally understood that I had to include it in my microservices project so I can tell the typescript compiler of what file it should be aware of.
Because I have structure all my files in a src folder in the root, I had to tell the compiler to include ["./src/**/*] and exclude["./node_modules"] because if I don't exclude it, we will issue a compiling performance and finally had to make sure to inform the compiler to include #types/jest without being referenced in a source file, in my case: "types": ["jest"] and allowJs to true so my javascript files can be part of my program. This had done the trick.
Now I must figure out why when building a new project, I don't receive these errors without tsconfig.json file. If some knows the answer, I would appreciate it!!