What is the difference between [Test] and [TestCase] in NUnit?

Short answer: [Test] marks a standard test method without parameters. [TestCase] provides inline parameter values to run the test multiple times with different inputs.

Real-world example (ShopNest)

ShopNest unit tests cover pricing and discount rules so a bad coupon change fails in CI before customers see it.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.