add kafka test container

src/main/kotlin/ltd/hlaeja/test/container/KafkaTestContainer.kt

@@ -0,0 +1,11 @@
+package ltd.hlaeja.test.container
+
+import ltd.hlaeja.test.container.extension.KafkaTestExtension
+import org.junit.jupiter.api.extension.ExtendWith
+import org.springframework.test.context.ContextConfiguration
+
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+@ExtendWith(KafkaTestExtension::class)
+@ContextConfiguration(initializers = [KafkaTestExtension::class])
+annotation class KafkaTestContainer

src/main/kotlin/ltd/hlaeja/test/container/extension/KafkaTestExtension.kt

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+package ltd.hlaeja.test.container.extension
+
+import ltd.hlaeja.test.container.kafka.TestContainerKafka
+import org.junit.jupiter.api.extension.BeforeAllCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.springframework.boot.test.util.TestPropertyValues
+import org.springframework.context.ApplicationContextInitializer
+import org.springframework.context.ConfigurableApplicationContext
+
+class KafkaTestExtension : BeforeAllCallback, ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+    override fun initialize(applicationContext: ConfigurableApplicationContext) {
+        TestPropertyValues.of(TestContainerKafka.props()).applyTo(applicationContext.environment)
+    }
+
+    override fun beforeAll(context: ExtensionContext) {
+        if (!TestContainerKafka.kafka.isRunning) {
+            TestContainerKafka.kafka.start()
+        }
+    }
+}

src/main/kotlin/ltd/hlaeja/test/container/kafka/TestContainerKafka.kt

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+package ltd.hlaeja.test.container.kafka
+
+import org.testcontainers.kafka.ConfluentKafkaContainer
+
+object TestContainerKafka {
+
+    val kafka: ConfluentKafkaContainer = ConfluentKafkaContainer("confluentinc/cp-kafka:8.0.0")
+        .withReuse(true)
+
+    fun props(): Map<String, String> = mapOf(
+        "spring.kafka.bootstrap-servers" to kafka.bootstrapServers,
+    )
+}