Tests kotlin

--- description: Enforce TDD workflow for Kotlin. Write Kotest tests first, then implement. Verify 80%+ coverage with Kover. --- # Kotlin TDD Command This command enforces test-driven development methodology for Kotlin code using Kotest, MockK, and Kover. ## What This Command Does 1. Define Types/Interfaces: Scaffold function signatures first 2. Write Kotest Tests: Create comprehensive test specs (RED) 3. Run Tests: Verify tests fail for the right reason 4. Implement Code: Write minimal code to pass (GREEN) 5. Refactor: Improve while keeping tests green 6. Check Coverage: Ensure 80%+ coverage with Kover ## When to Use Use /kotlin-test when: - Implementing new Kotlin functions or classes - Adding test coverage to existing Kotlin code - Fixing bugs (write failing test first) - Building critical business logic - Learning TDD workflow in Kotlin ## TDD Cycle `` RED -> Write failing Kotest test GREEN -> Implement minimal code to pass REFACTOR -> Improve code, tests stay green REPEAT -> Next test case ` ## Example Session ``text User: /kotlin-test I need a function to validate user registration requests Agent: # TDD Session: Registration Validator ## Step 1: Define Interface `kotlin // validator/RegistrationValidator.kt package com.example.validator data class RegistrationRequest( val name: String, val email: String, val password: String, ) sealed class ValidationResult { data object Valid : ValidationResult() data class Invalid(val errors: List<String>) : ValidationResult() } fun validateRegistration(request: RegistrationRequest): ValidationResult { TODO("not implemented") } ` ## Step 2: Write Kotest Tests (RED) `kotlin // validator/RegistrationValidatorTest.kt package com.example.validator import io.kotest.core.spec.style.FunSpec import io.kotest.matchers.shouldBe import io.kotest.matchers.types.shouldBeInstanceOf class RegistrationValidatorTest : FunSpec({ test("valid registration returns Valid") { val request = RegistrationRequest( name = "Alice", email = "alice@example.com", password = "SecureP@ss1", ) val result = validateRegistration(request) result.shouldBeInstanceOf<ValidationResult.Valid>() } test("blank name returns Invalid") { val request = RegistrationRequest( name = "", email = "alice@example.com", password = "SecureP@ss1", ) val result = validateRegistration(request) val invalid = result.shouldBeInstanceOf<ValidationResult.Invalid>() invalid.errors shouldBe listOf("Name is required") } test("invalid email returns Invalid") { val request = RegistrationRequest( name = "Alice", email = "not-an-email", password = "SecureP@ss1", ) val result = validateRegistration(request) val invalid = result.shouldBeInstanceOf<ValidationResult.Invalid>() invalid.errors shouldBe listOf("Invalid email format") } test("short password returns Invalid") { val request = RegistrationRequest( name = "Alice", email = "alice@example.com", password = "short", ) val result = validateRegistration(request) val invalid = result.shouldBeInstanceOf<ValidationResult.Invalid>() invalid.errors shouldBe listOf("Password must be at least 8 characters") } test("multiple errors returns all errors") { val request = RegistrationRequest( name = "", email = "bad", password = "short", ) val result = validateRegistration(request) val invalid = result.shouldBeInstanceOf<ValidationResult.Invalid>() invalid.errors.size shouldBe 3 } }) ` ## Step 3: Run Tests - Verify FAIL `bash $ ./gradlew test RegistrationValidatorTest > valid registration returns Valid FAILED kotlin.NotImplementedError: An operation is not implemented FAILED (5 tests, 0 passed, 5 failed) ` ✓ Tests fail as expected (NotImplementedError). ## Step 4: Implement Minimal Code (GREEN) `kotlin // validator/RegistrationValidator.kt package com.example.validator private val EMAIL_REGEX = Regex("^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$") private const val MIN_PASSWORD_LENGTH = 8 fun validateRegistration(request: RegistrationRequest): ValidationResult { val errors = buildList { if (request.name.isBlank()) add("Name is required") if (!EMAIL_REGEX.matches(request.email)) add("Invalid email format") if (request.password.length < MIN_PASSWORD_LENGTH) add("Password must be at least $MIN_PASSWORD_LENGTH characters") } return if (errors.isEmpty()) ValidationResult.Valid else ValidationResult.Invalid(errors) } ` ## Step 5: Run Tests - Verify PASS ``bash $ ./gradlew test RegistrationValidatorTest > valid registration returns V