🧪 JUnit Test Isolation — One Small Detail That Changed Everything
Today I learned that JUnit creates a brand-new instance of your test class for every "@test" method by default.
"@TestInstance(TestInstance.Lifecycle.PER_METHOD)"
What happens?
- "test1()" runs → counter becomes "1"
- JUnit destroys that object
- "test2()" gets a fresh instance → counter starts at "0" again and becomes "2"
This prevents tests from accidentally sharing state and affecting each other.
📁 Bonus Gradle Gotcha:
If your tests are inside "src/main/kotlin", Gradle ignores them and shows:
"Task :test NO-SOURCE"
Move them to:
"src/test/kotlin"
and your tests run correctly. Use:
"./gradlew test -i"
to see "println()" output in the terminal.
Small detail, big debugging lesson. 🚀
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