[expect-type] usage with create-react-app

[LorenzHenk]

I'd like to use this library.

to test it, I've created a new react-app with typescript (yarn create react-app myapp --template typescript).

In the existing App.test.tsx, I've added the following statement to the existing test:

  expectTypeOf(1).toBeString();

In the IDE (I'm using VS Code), this shows an error (An argument for 'MISMATCH' was not provided.).
But when running the test with yarn test, no errors are shown.
Test files don't seem to be type checked.

How did you enable type checking for your test files?

[mmkal]

I'm not familiar with create-react-app - is there a script that runs the typescript compiler? That's where the errors would he caught.

[LorenzHenk]

Seems like the TS config is embedded here: https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js#L102

[mmkal]

Is there a yarn build command or similar that catches type errors? That's what it suggests in the create-react-app docs:

Type errors will show up in the same console as the build one. You'll have to fix these type errors before you continue development or build your project

[mmkal]

@LorenzHenk have converted this to a Q&A Discussion since I don't think there's an issue with expect-type here. Did you get it working with create-react-app in the end?

[LorenzHenk]

@mmkal you're right, yarn build fails.
Running the command tsc fails as well.

I just added the script

"ts:check": "tsc"

to package.json and can now run yarn test && yarn ts:check to make sure the tests are working correctly.