CODEWITHSUNDEEP
typescripttestingjestjstesting-library
Laura Beatris
Laura Beatris

Reputation: 1922

Types definitions aren't loading when executing Jest tests

I'm building an open-source library of test utilities which also includes custom tech matches. But when creating test files and running them, a lot of errors are being raised regarding type definitions.

Refer to the following errors when running yarn testenter image description here

The errors are related to two different type definitions, which are:

My question is: Why the type definitions aren't loading? I presume that there should be something wrong regarding the TS compiler or Jest configs

PR with the tests code

Upvotes: 3

Views: 3766

Answers (1)

Nickofthyme
Nickofthyme

Reputation: 4327

Very good question, I have run into this issue so many times. I use jest-extended which says in their readme that you may need to import the type definitions in a global.d.ts file. Then add the global.d.ts file to the typeRoots in your tsconfig.json.

I also created my own jest matcher internal to my repo and add that file to my typeRoots as well.

A huge note is that all of this will still fail if these files are NOT included in your tsconfig.json. For example, you have a global.d.ts file but your rootDir is set to src (excluding the global.d.ts).

That said here is the repo you can reference for a working example. Here is the custom matcher type definitions, global.d.ts importing jest-extended and tsconfig.json typeRoots definition.

All in all I think you just need to add the custom types explicitly to the compilerOptions. And make sure to include your custom type files in your tsconfig.json file selection.

{
  "compilerOptions": {
    "typeRoots": ["./node_modules/@types", "./**/*.d.ts", "./scripts/custom_matchers.ts"]
  }
}

Upvotes: 4

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