Is it a good practices to add tests files in the tsconfig.json exclude field?

Question

I often see "exclude": ["**/*.test.ts", "**/*.test.tsx"] in project tsconfig file.

Sometimes there is a tsconfig.json without this but another tsconfig.build.json which override this file and add this exclusion.

My questions are:

• what are the pros and cons of doing so?
• Is it considered as a good practice?

Answer 1

What are the pros and cons of doing so?

• Pros
  • The tests won't be compiled to JavaScript
  • Smaller build size
  • Smaller compile time
• Cons
  • To run the tests, you need to have TypeScript installed
  • (And some testing library which supports TypeScript out of the box)

Is it considered as a good practice?

Depends on your use case. Smaller builds are good, but at what cost? Does your module need to be tested by everyone, or is a single test on the build enough?

Also, if you have something like ts-jest in your devDependencies, your tests will be run as pure TypeScript, so you wouldn't need to compile them.

Answer 2

I agree with the first answer. Just wanted to comment (but don't have enough reputation yet to do it).

In case we want to exclude those from tsconfig.json and want to apply the quality standards to code anyway we can create another file, for instance, tsconfig.eslint.json and extend tsconfig there. Then pass an empty array to exclude object. Then link this file for eslint config to use.

Example of tsconfig.eslint.json:

{
  "extends": "./tsconfig",
  "exclude": []
}