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

[TidyIQ]

TypeScript Version: 3.4.5

Code

package.json dev dependencies:

  "devDependencies": {
    "@types/classnames": "^2.2.7",
    "@types/cookie": "^0.3.2",
    "@types/facebook-js-sdk": "^3.2.1",
    "@types/graphql": "^14.2.0",
    "@types/jest": "^24.0.12",
    "@types/material-ui": "^0.21.6",
    "@types/next": "^8.0.4",
    "@types/nookies": "^1.1.0",
    "@types/react": "^16.8.15",
    "@types/react-dom": "^16.8.4",
    "@types/styled-jsx": "^2.2.8",
    "@typescript-eslint/eslint-plugin": "^1.7.0",
    "@typescript-eslint/parser": "^1.7.0",
    "@zeit/next-typescript": "^1.1.1",
    "apollo-cache-inmemory": "^1.5.1",
    "dotenv-webpack": "^1.7.0",
    "eslint": "^5.16.0",
    "eslint-config-prettier": "^4.2.0",
    "eslint-plugin-jest": "^22.5.1",
    "eslint-plugin-prettier": "^3.0.1",
    "eslint-plugin-react": "^7.12.4",
    "eslint-plugin-react-hooks": "^1.6.0",
    "jest": "^24.7.1",
    "nookies": "^2.0.5",
    "prettier": "^1.17.0",
    "react-testing-library": "^7.0.0",
    "ts-jest": "^24.0.2",
    "typescript": "^3.4.5"
  }

tsconfig.json:

{
    "compilerOptions": {
        "allowJs": true,
        "allowSyntheticDefaultImports": true,
        "jsx": "preserve",
        "lib": [
            "dom",
            "esnext"
        ],
        "module": "esnext",
        "target": "esnext",
        "moduleResolution": "node",
        "noEmit": true,
        "noUnusedLocals": true,
        "noUnusedParameters": true,
        "preserveConstEnums": true,
        "removeComments": false,
        "skipLibCheck": true,
        "sourceMap": true,
        "strict": true,
    },    
    "exclude": [
        "node_modules",
        "**/*.spec.ts",
        "**/*.spec.tsx",
        "**/*.test.ts",
        "**/*.test.tsx",
    ]
}

file.test.tsx:

test()

Expected behavior:

No issue. @types/jest is already installed. All other @types/* are working fine.

Actual behavior:

Error:

Cannot find name 'test'. Do you need to install type definitions for a test runner? Try `npm i @types/jest` or `npm i @types/mocha`.ts(2582)

[TidyIQ]

Nevermind, the example I was provided added the excludes to tsconfig but if I remove it then it works fine. I don't know why they would exclude the test files but whatever, problem solved.

[valters]

This ☝️ is the answer. Some tutorials/articles instruct you to add "*/.spec.ts" and similar to "excludes" but that makes VS Code to be unable to find the jest types. Removing the exclude solves the problem.

[ilgazil]

But removing these from excludes will deploy tests in outDir while building...

[joffarex]

@ilgazil You should not have tests folder in your specified rootDir in the first place.

[andreElrico]

I solved this by adding

to tsconfig.app.json of the app I tried to build

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

hope this helps...

[alexandrubb23]

I solved by adding to tsconfig.json

"exclude": ["**/tests/*.test.ts"]

My scripts are located inside of tests folder.

[mikhaili]

I solved by adding in tsconfig.json
"types": [
"@types/jest"
]

or more ugly way add in one of the type files:
///

[AshwaryaSmridhi]

Solved this by adding to compilerOptions:

"compilerOptions": {
    ...,
    "types": ["...", "@types/jest"],
    ....
  },