Kotlin + Java | add a few Kotlin implementations to operate side-by-side with Java

server/gradle.properties

@@ -1,17 +1,20 @@
 apacheCommonsVersion=4.4
+
 assertjVersion=3.26.0
 archUnitVersion=1.3.0
-
 hamcrestVersion=2.2
 
 jakartaAnnotationVersion=3.0.0
 jakartaInjectVersion=2.0.1
 
 junitJupiterVersion=5.10.2
 
+kotlinVersion=2.0.0
+
 lombokPluginVersion=8.6
 lombokVersion=1.18.32
 
 mockitoVersion=5.12.0
+
 springBootVersion=3.3.0
 springDependencyManagementVersion=1.1.5

server/loans/core/build.gradle

@@ -1,6 +1,24 @@
+import static org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+
+plugins {
+  id 'org.jetbrains.kotlin.jvm' version "${kotlinVersion}"
+}
+
 group = 'ee.rsx.kata.bank'
 version = '1.0.0-SNAPSHOT'
 
 dependencies {
   implementation project(":loans-api")
 }
+
+compileKotlin {
+  compilerOptions {
+    jvmTarget = JVM_17
+  }
+}
+
+compileTestKotlin {
+  compilerOptions {
+    jvmTarget = JVM_17
+  }
+}

server/loans/core/src/main/kotlin/ee/rsx/kata/bank/loans/usecases/ProvideLoanConfiguration.kt

@@ -0,0 +1,23 @@
+package ee.rsx.kata.bank.loans.usecases
+
+import ee.rsx.kata.bank.loans.domain.limits.LoanLimitsConfig
+import ee.rsx.kata.bank.loans.domain.limits.gateway.LoanConfigGateway
+import ee.rsx.kata.bank.loans.validation.limits.LoadValidationLimits
+import ee.rsx.kata.bank.loans.validation.limits.ValidationLimitsDTO
+import jakarta.inject.Named
+
+@Named
+internal class ProvideLoanConfiguration(
+  private val gateway: LoanConfigGateway
+) : LoadValidationLimits {
+
+  override fun invoke() = gateway.loadLimits().toDto()
+
+  private fun LoanLimitsConfig.toDto() =
+    ValidationLimitsDTO(
+      minimumLoanAmount,
+      maximumLoanAmount,
+      minimumLoanPeriodMonths,
+      maximumLoanPeriodMonths
+    )
+}

server/loans/core/src/main/kotlin/ee/rsx/kata/bank/loans/usecases/SsnValidation.kt

@@ -0,0 +1,27 @@
+package ee.rsx.kata.bank.loans.usecases
+
+import ee.rsx.kata.bank.loans.domain.ssn.SocialSecurityNumber
+import ee.rsx.kata.bank.loans.validation.ssn.SsnValidationResultDTO
+import ee.rsx.kata.bank.loans.validation.ssn.SsnValidationResultDTO.invalidResultWith
+import ee.rsx.kata.bank.loans.validation.ssn.SsnValidationResultDTO.okResultWith
+import ee.rsx.kata.bank.loans.validation.ssn.ValidateSocialSecurityNumber
+import jakarta.inject.Named
+import java.lang.RuntimeException
+import java.time.format.DateTimeParseException
+
+@Named
+internal class SsnValidation : ValidateSocialSecurityNumber {
+
+  override fun on(ssn: String): SsnValidationResultDTO =
+    try {
+      val validSsn = SocialSecurityNumber(ssn)
+      okResultWith(validSsn.value)
+    } catch (e: RuntimeException) {
+      when (e) {
+        is IllegalArgumentException,
+        is IllegalStateException,
+        is DateTimeParseException -> invalidResultWith(ssn)
+        else -> throw e
+      }
+    }
+}

server/loans/core/src/test/kotlin/ee/rsx/kata/bank/loans/usecases/SsnValidationTest.kt

@@ -0,0 +1,78 @@
+package ee.rsx.kata.bank.loans.usecases
+
+import ee.rsx.kata.bank.loans.validation.ssn.SsnValidationResultDTO
+import ee.rsx.kata.bank.loans.validation.ssn.ValidationStatus.INVALID
+import ee.rsx.kata.bank.loans.validation.ssn.ValidationStatus.OK
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+
+@DisplayName("SSN Validation")
+internal class SsnValidationTest {
+
+  private lateinit var ssnValidation: SsnValidation
+
+  @BeforeEach
+  fun setup() {
+    ssnValidation = SsnValidation()
+  }
+
+  @Test
+  fun `result is OK, for a given valid SSN value`() {
+    val validSsnValue = "50212104262"
+
+    val result = ssnValidation.on(validSsnValue)
+
+    assertThat(result).isEqualTo(
+      SsnValidationResultDTO(validSsnValue, OK)
+    )
+  }
+
+  @Nested
+  @DisplayName("result is INVALID, for a given SSN value")
+  internal inner class ResultIsInvalidForAGivenSsnValue {
+
+    @Test
+    fun `having invalid date`() {
+      val invalidDate = "021310"
+      val invalidSsnValue = "5${invalidDate}4262"
+
+      val result = ssnValidation.on(invalidSsnValue)
+
+      assertThat(result).isEqualTo(
+        expectedInvalidResultFor(invalidSsnValue)
+      )
+    }
+
+    @Test
+    fun `having invalid checksum`() {
+      val invalidChecksum = "3"
+      val invalidSsnValue = "5021210426${invalidChecksum}"
+
+      val result = ssnValidation.on(invalidSsnValue)
+
+      assertThat(result).isEqualTo(
+        expectedInvalidResultFor(invalidSsnValue)
+      )
+    }
+
+    @Test
+    fun `having invalid century prefix`() {
+      val invalidCenturyPrefix = "7"
+      val invalidSsnValue = "${invalidCenturyPrefix}0212104262"
+
+      val result = ssnValidation.on(invalidSsnValue)
+
+      assertThat(result).isEqualTo(
+        expectedInvalidResultFor(invalidSsnValue)
+      )
+    }
+  }
+
+  companion object {
+    private fun expectedInvalidResultFor(invalidSsnValue: String) =
+      SsnValidationResultDTO(invalidSsnValue, INVALID)
+  }
+}

server/loans/gw-eligibility/build.gradle

@@ -1,6 +1,24 @@
+import static org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+
+plugins {
+  id 'org.jetbrains.kotlin.jvm' version "${kotlinVersion}"
+}
+
 group = 'ee.rsx.kata.bank'
 version = '1.0.0-SNAPSHOT'
 
 dependencies {
   implementation project(":loans-core")
 }
+
+compileKotlin {
+  compilerOptions {
+    jvmTarget = JVM_17
+  }
+}
+
+compileTestKotlin {
+  compilerOptions {
+    jvmTarget = JVM_17
+  }
+}