How do I exclude files from svelte-kit build?

Question

If I run npm run build with SvelteKit it seems to include all files from the src folder. Is it possible to exclude a certain file type (eg. *test.js)?

Example

1. Select demo app with npm init svelte@next my-app

2. Add the following code to src/routes/todos/foo.test.js

   describe('foo', () => {
     it('temp', () => {
       expect(true).toBe(false)
     })
   })
   

3. npm run build

4. npm run preview

Result: describe is not defined

Workaround

Move tests outside of src