Having trouble locating the name 'it' in Jest TypeScript

Question

Having trouble locating the name 'it' in Jest TypeScript

After setting up Jest in React + TypeScript, I encountered an error when trying to run a test using the command npm test. The error message displayed was:

Cannot find name 'it'. Do you need to install type definitions for a test runner? Try `npm i @types/jest` or `npm i @types/mocha`.

I have already installed Jest types and removed types from tsconfig.json, but the error persists.

{
      "compilerOptions": {
        "target": "es6",
        "lib": ["dom", "dom.iterable", "esnext"],
        "allowJs": true,
        "skipLibCheck": true,
        "esModuleInterop": true,
        "allowSyntheticDefaultImports": true,
        "strict": true,
        "forceConsistentCasingInFileNames": true,
        "module": "esnext",
        "moduleResolution": "node",
        "plugins": [{ "name": "typescript-tslint-plugin" }],
        "resolveJsonModule": true,
        "isolatedModules": true,
        "noEmit": true,
        "jsx": "preserve",
        "pretty": true,
        "baseUrl": "src",
        "types": ["jest"],
        "typeRoots": ["./src/types"],
        "suppressImplicitAnyIndexErrors": true
      },
      "include": ["src", "node_modules/@types/jest"],
      "exclude": ["node_modules"]
    }

Package.json


        "jest": {
            "transform": {
              ".(ts|tsx)": "ts-jest"
            },
            "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
            "moduleFileExtensions": [
              "ts",
              "tsx",
              "js"
            ]
          },
          "devDependencies": {
            "@babel/plugin-proposal-export-default-from": "^7.2.0",
            "@types/enzyme": "^3.9.3",
            "@types/jest": "^24.0.14",
            ...
            "tslint-react-hooks": "^2.1.0"
          }

typescript npm jestjs ts-jest

Answer 1

Answer №1

Setting up Jest for TypeScript

npm install -D jest @types/jest ts-jest

Configure jest.config.js in root directory

module.exports = {
  roots: ['<rootDir>/src'],
  transform: {
    '^.+\\.tsx?$': 'ts-jest',
  },
  testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
}

Create a tsconfig.json file

{
    "compilerOptions": {
     ...

      "types": ["reflect-metadata", "jest"],
      "typeRoots": ["./types", "./node_modules/@types"]
     
     ...
    },
    "exclude": ["node_modules", "**/*.spec.ts", "**/*.test.ts"],
    "include": ["./src/**/*.tsx", "./src/**/*.ts"]
  }

Answer 2

Setting up Jest for TypeScript

npm install -D jest @types/jest ts-jest

Configure jest.config.js in root directory

module.exports = {
  roots: ['<rootDir>/src'],
  transform: {
    '^.+\\.tsx?$': 'ts-jest',
  },
  testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
}

Create a tsconfig.json file

{
    "compilerOptions": {
     ...

      "types": ["reflect-metadata", "jest"],
      "typeRoots": ["./types", "./node_modules/@types"]
     
     ...
    },
    "exclude": ["node_modules", "**/*.spec.ts", "**/*.test.ts"],
    "include": ["./src/**/*.tsx", "./src/**/*.ts"]
  }

Answer 3

Answer №2

To incorporate this into your testing documents, simply add the following line:

import '@types/jest';

Answer 4

To incorporate this into your testing documents, simply add the following line:

import '@types/jest';

Answer 5

Answer №3

To resolve the issue, I included "@types/jest" in the "types" section of my tsconfig.json.

Answer 6

To resolve the issue, I included "@types/jest" in the "types" section of my tsconfig.json.

Answer 7

Answer №4

Initially, the issue I encountered stemmed from my tsconfig.json being configured as follows:

  "include": [
    "src"
  ]

To resolve this, I had to modify it to:

  "include": [
    "src",
    "tests"
  ]

(Where all my tests are located in the 'tests' directory)

Answer 8

Initially, the issue I encountered stemmed from my tsconfig.json being configured as follows:

  "include": [
    "src"
  ]

To resolve this, I had to modify it to:

  "include": [
    "src",
    "tests"
  ]

(Where all my tests are located in the 'tests' directory)

Answer 9

Answer №5

To include the following code in tsconfig.json file:

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

Answer 10

To include the following code in tsconfig.json file:

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

Answer 11

Answer №6

Despite attempting various solutions, none of them worked in my situation. The breakthrough came when I referenced the type definitions using

/// <reference types="@types/jest" />

at the beginning of the file. Prior to that, it was necessary to install the @types/jest package. However, a drawback is that this must be imported into every file.

Answer 12

Despite attempting various solutions, none of them worked in my situation. The breakthrough came when I referenced the type definitions using

/// <reference types="@types/jest" />

at the beginning of the file. Prior to that, it was necessary to install the @types/jest package. However, a drawback is that this must be imported into every file.

Answer 13

Answer №7

To start, first you need to install @types/jest using the command npm install @types/jest. After that, you will need to configure jest by adding the following code to your package.json file:

// package.json
// ...
"jest": {
  "globals": {
    "ts-jest": {
      "tsconfig": "path_to_our_tests/jest.tsconfig.json"
    }
  }
}

Next, create a jest.tsconfig.json file in your test directory and modify it as follows:

// path_to_our_tests/jest.tsconfig.json"
{
  "extends": "../tsconfig.json",
  "compilerOptions": {
    "types": ["jest"]
  },
  "include": ["../src", "**/*"]
}

Make sure that your root tsconfig.json file only includes source files, not test files:

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

This approach allows you to customize jest configurations without affecting the global settings of your project, thus avoiding potential issues with your code.

Both configurations should successfully pass a compiler check by executing:

npx tsc && npx tsc -p path_to_our_tests/jest.tsconfig.json

Answer 14

To start, first you need to install @types/jest using the command npm install @types/jest. After that, you will need to configure jest by adding the following code to your package.json file:

// package.json
// ...
"jest": {
  "globals": {
    "ts-jest": {
      "tsconfig": "path_to_our_tests/jest.tsconfig.json"
    }
  }
}

Next, create a jest.tsconfig.json file in your test directory and modify it as follows:

// path_to_our_tests/jest.tsconfig.json"
{
  "extends": "../tsconfig.json",
  "compilerOptions": {
    "types": ["jest"]
  },
  "include": ["../src", "**/*"]
}

Make sure that your root tsconfig.json file only includes source files, not test files:

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

This approach allows you to customize jest configurations without affecting the global settings of your project, thus avoiding potential issues with your code.

Both configurations should successfully pass a compiler check by executing:

npx tsc && npx tsc -p path_to_our_tests/jest.tsconfig.json

Answer 15

Answer №8

Trying out the latest version of ts-loader, like v6.0.1 or higher, might work wonders.

Answer 16

Trying out the latest version of ts-loader, like v6.0.1 or higher, might work wonders.

Answer 17

Answer №9

After realizing I needed jest, I promptly installed it as a devDependency:

npm install --save-dev @types/jest

Answer 18

After realizing I needed jest, I promptly installed it as a devDependency:

npm install --save-dev @types/jest

Answer 19

Answer №10

After trying several different approaches, I couldn't get any of them to work for me. Even importing '@types/jest' didn't solve the issue I encountered when running npm test to import 'jest'. The only method that worked for me was importing { describe, it, beforeEach } from '@jest/globals' in my test files.

Answer 20

After trying several different approaches, I couldn't get any of them to work for me. Even importing '@types/jest' didn't solve the issue I encountered when running npm test to import 'jest'. The only method that worked for me was importing { describe, it, beforeEach } from '@jest/globals' in my test files.

Answer 21

Answer №11

Upon reviewing the results of executing npx ts-jest config:init (as recommended in the documentation for ts-jest), I found that including this line at the beginning of my jest.config.js file resolved the issue:

/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */

Answer 22

Upon reviewing the results of executing npx ts-jest config:init (as recommended in the documentation for ts-jest), I found that including this line at the beginning of my jest.config.js file resolved the issue:

/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */

Answer 23

Answer №12

For those who have successfully set up Jest and TypeScript in their environment, the solution to address this issue is as simple as installing @types/jest using your chosen package manager:

npm install --save-dev @types/jest
pnpm add --save-dev @types/jest
yarn add --dev @types/jest
bun add --dev @types/jest

Answer 24

For those who have successfully set up Jest and TypeScript in their environment, the solution to address this issue is as simple as installing @types/jest using your chosen package manager:

npm install --save-dev @types/jest
pnpm add --save-dev @types/jest
yarn add --dev @types/jest
bun add --dev @types/jest

Answer 25

Answer №13

After encountering an issue, I discovered that the root cause was the absence of a jest folder in my ./node_modules/@types directory. Despite running npm i @types/jest and being told that the package was up to date, it was nowhere to be found in the expected location within my node_modules/@types.

To resolve this, I took the step of globally installing @types/jest and then manually copying the installed package into my ./node_modules/@types directory.

To execute the global installation of @jest/types, use the following command:

npm i -g @types/jest

To determine the path of your global node_modules, input the following command:

npm root -g

To verify the presence of the @types/jest package in that location, run:

ls $(npm root -g)/@types

Next, navigate to your project directory and perform the following command:

cp -R $(npm root -g)/@types/jest ./node_modules/@types

This will copy the package from the global directory to your local node_modules.

Answer 26

After encountering an issue, I discovered that the root cause was the absence of a jest folder in my ./node_modules/@types directory. Despite running npm i @types/jest and being told that the package was up to date, it was nowhere to be found in the expected location within my node_modules/@types.

To resolve this, I took the step of globally installing @types/jest and then manually copying the installed package into my ./node_modules/@types directory.

To execute the global installation of @jest/types, use the following command:

npm i -g @types/jest

To determine the path of your global node_modules, input the following command:

npm root -g

To verify the presence of the @types/jest package in that location, run:

ls $(npm root -g)/@types

Next, navigate to your project directory and perform the following command:

cp -R $(npm root -g)/@types/jest ./node_modules/@types

This will copy the package from the global directory to your local node_modules.

Having trouble locating the name 'it' in Jest TypeScript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

Answer №10

Answer №11

Answer №12

Answer №13

Similar questions

Ways to obscure a React component or JSX file

The problem encountered with the Enzyme mount API is a TypeError where it is unable to read the property 'find' of an undefined variable

Elements that allow for asynchronous data submission without requiring a traditional submit button

Is there a method to ensure the strong typing of sagas for dispatching actions?

Ways to integrate user input into the header of an Angular HTTP post method

What is the best way to implement multiple ternary operators within HTML code?

Updating the MaxMind GeoLite2 database is a simple process that can be

Creating a unit test to verify the offline status of the app in a react-native environment

Learn how to easily toggle table column text visibility with a simple click

Are union types strictly enforced?

@angular/common@~5.1.1 is needed as a peer dependency for @angular/[email protected], however it is not currently installed

Here are the steps to fix the error "SyntaxError: Cannot use import statement outside a module" when running a Jest test case

Discovering the data type in Typescript through the use of Generics

What is the significance of having both nulls in vue's ref<HTMLButtonElement | null>(null)?

Passing headers using a universal method in HTTP CRUD process

understanding the life cycle of components in Ionic

Include module A in module B, even though module A has already included module B's Angular

Different ways to maintain the original syntax highlighting colors in JavaScript console

Creating NodeJS Lambda - identical content, distinct SHA checksum

Creating a non-editable form or text field upon clicking the Submit button