Regarding testing, I think the Svelte adaptation of Testing Library seems to be working pretty well! And in general I think Kent C. Dodds' (the original author of react-testing-library) approach to testing front end components is very sound and reasonable. Read for example kentcdodds.com/blog/write-tests.
So I'd recommend going with svelte-testing-library, standard Jest unit tests for isolated logic, and probably Cypress if you want some E2E tests.
Regarding testing, I think the Svelte adaptation of Testing Library seems to be working pretty well! And in general I think Kent C. Dodds' (the original author of react-testing-library) approach to testing front end components is very sound and reasonable. Read for example kentcdodds.com/blog/write-tests.
So I'd recommend going with svelte-testing-library, standard Jest unit tests for isolated logic, and probably Cypress if you want some E2E tests.
Thanks!