Dealing with the configuration file tsconfig.json can be a bit tricky when both your IDE (like Visual Studio Code) and TypeScript use it for their own purposes.

Solution checklist to address the initial issue:

(applicable for TypeScript and Jest)

1. Ensure that you have @types/jest and @types/node installed.
2. Make sure to include these types in your tsconfig.json under

   "types": ["jest", "node"]

3. Avoid excluding your tests or test directory from your tsconfig.json configuration using the excluded property.

Impact on transpilation process

If you are transpiling from TypeScript to JavaScript using tools like tsc which rely on tsconfig.json, your tests may also get transpiled alongside your code (resulting in .js files in your build directory).

Alternatively, you can:

1. Use a separate tsconfig.prod.json file with customized settings such as inlineSource, sourceMaps, and

   inlineSourceMaps</code. To compile using this config, run <code>tsc --project tsconfig.prod.json

   .
2. Employ terminal commands with specific flags to override default configurations. For instance, using

   npx tsc --inlineSourceMap false --declarationMap false --inlineSources false --sourceMap false

   . Utilize --excludeFiles or --excludeDirectories to exclude tests from compilation based on documentation.

You can also opt to use a tool like rimraf to remove unnecessary files during the build process. This approach might be simpler than modifying configurations and easier to maintain. Use a command like yarn rimraf build/**/*.test.js for this purpose.

Restarting IDE or TypeScript service

Remember, sometimes your IDE (or TypeScript service) needs a moment to recognize changes. Look for an annotation at the bottom of your IDE window (e.g., "TypeScript 4.2.1"). Click on it and select "Restart service" to ensure that the solution is effective before proceeding.

When working on my Angular project in Visual Studio Code, I made some changes to the tsconfig.json file by commenting out or removing certain types. Additionally, I added "jest" to the types section of the tsconfig.spec.json file.

Edit in File tsconfig.json

{
  "compilerOptions": {
    // "types": []
  }
}

Edit in File tsconfig.spec.json

{
  "compilerOptions": {
    "types": ["jest", "node"]
  }
}

Here is the solution that did the trick for me:

import '@types/jest';

After trying various solutions, none of them addressed the problem I was facing.

To resolve it, I found that including "@types/jest" in the types array within the tsconfig.json file did the trick.

To resolve this issue, I found a solution by including the tests/ folder in the "include" section of the tsconfig.json file:

"include": [
  "src/**/*.ts",
  "tests/*.ts"
] 

If you are also facing complaints from ESLint, make sure to add Jest to your .eslintrc.json file:

"env": {
  "es2020": true,
  "node": true,
  "jest": true
}

To fix this issue, you need to include Jest in your testing file:

import 'jest';

Another approach is to update your tsconfig.json file by adding the necessary configurations:

   "compilerOptions": {
     "types": [ "node", "jest" ],
     "moduleResolution": "node"
   }

If you are utilizing TSLint, check for unnecessary commas in your tsconfig.json file like this:

{
  "compileOnSave": true,
  "include": [
    "src"
  ],  // Remove any extraneous commas
}

In my specific situation (using Visual Studio Code, implementing Create React App, utilizing Yarn workspaces, working with Jest version 26, incorporating @types/jest, defining types as ["node", "jest"] in tsconfig.json) my tests were running smoothly, however, the IDE was consistently highlighting all instances of describe and it with red marks.

After numerous attempts, I finally managed to resolve this issue by reloading the Visual Studio Code window.

This specific setup has been effective for me. I made sure to include node_modules/@types in the typeRoots section.

{
  "compilerOptions": {
    // ...the rest of my configurations
    "typeRoots": ["node_modules/@types"],
    "types": ["jest", "node"]
  }
}

To make sure your tests are included in your project, you must specify the test path in the tsconfig.json file.

For example, if you have named your test path as tests/ and placed it in the root directory of your project, you need to add the following to the "include" parameter in the tsconfig file to ensure that test files are recognized:

1. Navigate to: tsconfig.json

2. Insert:

   "include": [
       "tests/*.<file_test_extension>",
   ],
   

   <file_test_extension>: ts | js | etc.

To resolve the issue, make sure to add your test path in tsconfig.json.

I managed to fix this problem by setting up both a tsconfig.json and a tsconfig.build.json at the root of my project. The tsconfig.json file includes all necessary options, such as:

"include": ["src/**/*", "test/**/*"],

For the tsconfig.build.json:

{
  "extends": "./tsconfig.json",
  "include": [ "src/**/*" ]
}

Additionally, update the package.json file (you may add a clean script if needed):

"scripts": {
  "clean": "rm -rf dist",
  "build": "npm run clean && tsc --build tsconfig.build.json,
  ...
}

Make sure to create a separate tsconfig.json specifically for the test folder __tests__:

{
    "extends": "../tsconfig.json",
    "compilerOptions": {
        "baseUrl": "./",
        "outDir": "../build",
        "noEmit": true,
        "rootDir": "../",
    },
   "exclude": ["node_modules"],
}

This configuration will inherit from the main tsconfig.json located in the root directory:

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "moduleResolution": "node",
    "outDir": "./lib",
    "rootDir": "./src",
    "strict": true,
    "noImplicitAny": true,
    "esModuleInterop": true,
  },
  "exclude":: ["node_modules", "**/*.test.ts", "__tests__"]
}

By doing this, your test files will be excluded from the public build while still sharing common compiler options.

If you utilize includes alongside excludes, remember to reflect that in the extension file as well. Here's an example:

tsconfig.json

{
  "includes": ["src"],
  ...
}

tests/tsconfig.json

{
  "extends": "../tsconfig.json"
  "includes": ["../"]
}

This setup doesn't affect the contents of the build folder but helps Visual Studio Code recognize Jest types effectively.

If Visual Studio Code is opened in a parent directory above your project, it could cause issues. This occurred to me when working with Visual Studio solutions and having the entire solution open instead of just the project.

Ensure that Visual Studio Code is open at the root level of your project for optimal functionality.

Ever since the release of Jest version 25, users have had the ability to directly utilize the Jest global variables. Many find this feature particularly advantageous when paired with either setting the injectGlobals: false configuration option or using --injectGlobals=false from the command line interface.

As an illustration:

import { describe, expect, it, test } from '@jest/globals';

Alice Smith's provides a comprehensive solution. In my scenario, I found that the initial tsconfig.json file had the line

"exclude": ["node_modules", "**/__tests__/*"]

, which was causing the issue. Removing the line "**/__tests__/*" resolved the problem. Additionally, ensuring that the configuration includes

"types": ["jest"]

is crucial for success.

Furthermore, remember to close and reopen Visual Studio Code after making configuration adjustments. Neglecting this step led me to spend countless hours attempting various methods without success.

The solution recommended by Freewalker in the comments might easily go unnoticed. By removing "typeRoots" from the tsconfig file, which seemed to be conflicting with "types," the issue was successfully resolved.

Tips for Lerna monorepo users managing a monolithic repository

If you're working with a Lerna monorepo and facing issues, here are some steps that could help address them:

1. Make sure that the package "@types/jest" is included in the devDependencies of both the root package's package.json file and each individual package within the packages/ directory. Also, run lerna bootstrap to ensure these packages are installed or linked in the node_modules directories.

2. Verify that the configuration

   "types": ["node", "jest"]

   is present in your main tsconfig.json file.

3. To resolve any issues, consider adding import 'jest'; at the beginning of your individual *.test.ts files.

Here is the required step:

import {} from 'jasmine';

Please make sure to incorporate this line into your code.

In my situation, I came across a specific issue within one file. Although I couldn't pinpoint the exact problem, I managed to resolve it by including import {} from 'jest' in the file's imports.

Despite searching through the Jest issue tracker, Stack Overflow, and other resources, nothing seemed to address the issue at hand. It took a unique workaround to tackle this peculiar bug.

I also made sure to update the latest versions of jest, ts-jest, and @types/jest in the package.json file.

None of the solutions I found previously were able to help me with my issue.

The tools and frameworks I was using included:

• Angular 11
• Jest
• I removed anything related to Jasmine-Karma
• .spec files were located in the same folder as components (auto-generated by ng g)

To solve my problem, I added exclude to tsconfig.app.json (not tsconfig.json) to ignore all specification files when serving the app.

tsconfig.app.json

"exclude": [
    "**/*.spec.ts"
]

After making this change, both ng s and npm test now work correctly for me.

In my case, using explicit imports made a significant difference. Although other suggestions that included types were available, they didn't provide any further assistance as they had already been integrated

import { expect, describe, it, test } from '@jest/globals';

There are a few potential causes:

1. If you're encountering errors, check if the @types/jest package is installed. If not, try installing it. You can also specify the types in the tsconfig.json file by adding something like

   "typeRoots": ["node_modules/@types/", "./src/@types/", ".src/**/@types/"]

2. You might be facing a problem related to Visual Studio Code. One workaround could be to launch Visual Studio Code from within the project directory instead of its parent directory.

If you're dealing with persistent red squiggly lines in the VS Code IDE even after installing all necessary dev dependencies, try executing the Developer Reload Window command.

To do this quickly, follow these steps:

• Ctrl + Shift + P OR F1
• Next, type Reload and then choose the Developer: Reload Window option.

The problem I encountered appeared to be due to a discrepancy in version numbers between @types/jest and jest

My Solution:

I encountered this issue while working in Visual Studio Code. The fix was to execute the command npm i --save-dev @types/jest, and then make a modification in your

tsconfig.json

by adding

"jest" to the types section under "compilerOptions"

as shown below

"types": ["gapi", "gapi.auth2", "jest"],

After making these changes, the problem should be resolved.

Even after I had installed the type definition files for mocha from @types/mocha, the issue persisted.

If you are facing a similar problem, make sure to include node_modules/@types in your typeRoots configuration within the tsconfig.json file.

// tsconfig.json
{
  "compilerOptions": {
    "typeRoots": [
       ...
       "node_modules/@types/"
    ]
  }
}

For my Node.js Express.js project, I rely on Mocha, Chai, and chai-http for testing. Initially, I did not include types in compilerOptions in tsconfig.json, but adding the following settings made everything work smoothly:

{
  "compilerOptions": {
    // ...other configurations
    "types": ["mocha", "chai", "chai-http"]
  }
}

If you ever find yourself in need of adding the ts-jest dependency to your project, here's what you should do:

yarn add ts-jest -D

To configure this in your jest.config.ts file, make sure to change the line with preset: undefined to preset: 'ts-jest'

// Setting a preset for Jest's configuration
preset: 'ts-jest',

It is possible that the packages did not install correctly. Please verify if the package actually exists in the node_modules folder. Similar to a situation described in this Stack Overflow question, an error was encountered due to an empty node_modules directory for TypeScript.

After running npm i -D ts-jest, I successfully resolved the issue by installing the necessary module.