Kotest Over JUnit

Assertions Use Kotest Matchers

• Test assertions use Kotest's shouldBe / shouldNotBe / shouldThrow / shouldContain style — not JUnit's assertEquals / assertTrue / assertThrows
• Kotest matchers compose, read left-to-right (actual.shouldBe(expected)), and produce richer failure messages by default
• assertEquals(expected, actual) reads backwards relative to the prose it lives in; actual shouldBe expected doesn't

Test Structure Uses Kotest Specs

• New test classes extend a Kotest spec — DescribeSpec, BehaviorSpec, StringSpec — not @Test methods on a JUnit class
• The spec style lets you nest contexts and share setup naturally; the JUnit class style fights against that

JUnit Runner Is Fine

• Kotest tests run on the JUnit 5 platform via the Kotest JUnit runner — your existing Gradle test task picks them up with no changes
• This isn't a build-system migration; it's an assertion-and-structure migration
• Mixed projects (some classes JUnit, some Kotest) compile and run together; new tests go Kotest, old tests can be converted via the kotlinify-tests skill