Test the Finished Application

Run through the complete project workflow:

Start the app
→ choose currencies
→ edit the amount
→ swap the pair
→ verify live rate
→ change chart range
→ open Rates
→ save Favorites
→ log a conversion
→ open History
→ clear History
→ resize the browser

Also run:

npm run build

Test it

Confirm that the production build succeeds and that the main workflows still work together.

Checkpoint

You have a complete, testable Next.js currency-converter application.