Sometimes, we want to fix the “Cannot find name ‘describe’. Do you need to install type definitions for a test runner?” error with TypeScript and Jest.

In this article, we’ll look at how to fix the “Cannot find name ‘describe’. Do you need to install type definitions for a test runner?” error with TypeScript and Jest.

How to fix the “Cannot find name ‘describe’. Do you need to install type definitions for a test runner?” error with TypeScript and Jest?

To fix the “Cannot find name ‘describe’. Do you need to install type definitions for a test runner?” error with TypeScript and Jest, we can add 'jest' to the compilerOptions.types array in the tsconfig.json file for the Jest tests.

For instance, we write

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

to add 'jest' into the types array in the tsconfig.json for the test files.

This way, the TypeScript compiler will know that the Jest variables should be available.

Conclusion

To fix the “Cannot find name ‘describe’. Do you need to install type definitions for a test runner?” error with TypeScript and Jest, we can add 'jest' to the compilerOptions.types array in the tsconfig.json file for the Jest tests.