EU/EFTA, UK, Iceland, Liechtenstein, Norway: no test at all
Licences from these countries are exchanged as a formality — no practical or theory test, just the paperwork above and the eye test.
A second group also skips the practical test
Andorra, Australia, Canada, Israel, Japan, Monaco, Morocco, New Zealand, San Marino, Singapore, South Korea, Taiwan, Tunisia and the USA are exempt from the practical driving test for an ordinary car licence too. The only difference from the first group is for professional categories (truck, bus, taxi), which still need an extra theory exam.
Every other country: a practical driving test is required
Your canton's road traffic office arranges this. Professional licence categories also sit an additional theory exam. Rules can change and the exact list is maintained by the Federal Roads Office, so confirm your specific country with your canton before assuming either way.
Cost
The exchange itself costs more than CHF 100 and varies by canton. If a driving test is required, your canton will confirm the additional fee when you book it.