[WIP] Testkit: start configurable Testcontainer via mixin

testkit/src/main/scala/akka/kafka/testkit/scaladsl/TestcontainersKafkaPerClassLike.scala

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2014 - 2016 Softwaremill <http://softwaremill.com>
+ * Copyright (C) 2016 - 2019 Lightbend Inc. <http://www.lightbend.com>
+ */
+
+package akka.kafka.testkit.scaladsl
+
+import akka.kafka.testkit.internal.TestcontainersKafkaHelper
+import org.testcontainers.containers.KafkaContainer
+
+
+/**
+ * Uses [[https://www.testcontainers.org/ Testcontainers]] to start a Kafka broker in a Docker container.
+ * The Testcontainers dependency has to be added explicitly.
+ */
+trait TestcontainersKafkaPerClassLike extends KafkaSpec {
+
+  private var kafkaContainer: KafkaContainer = _
+  private var kafkaBootstrapServersInternal: String = _
+  private var kafkaPortInternal: Int = -1
+
+  private def requireStarted(): Unit =
+    require(kafkaPortInternal != -1, "Testcontainers Kafka hasn't been started via `setUp`")
+
+  override def kafkaPort: Int = {
+    requireStarted()
+    kafkaPortInternal
+  }
+
+  def bootstrapServers: String = {
+    requireStarted()
+    kafkaBootstrapServersInternal
+  }
+
+  def startKafka(confluentPlatformVersion: String): String = {
+    if (kafkaPortInternal == -1) {
+      val kafkaContainer = new KafkaContainer(confluentPlatformVersion)
+      configureKafka(kafkaContainer)
+      kafkaContainer.start()
+      kafkaBootstrapServersInternal = kafkaContainer.getBootstrapServers
+      kafkaPortInternal =
+        kafkaBootstrapServersInternal.substring(kafkaBootstrapServersInternal.lastIndexOf(":") + 1).toInt
+    }
+    kafkaBootstrapServersInternal
+  }
+
+  def stopKafka(): Unit =
+    if (kafkaPortInternal != -1) {
+      kafkaContainer.stop()
+      kafkaPortInternal = -1
+      kafkaContainer = null
+    }
+
+  /**
+   * Override this to select a different Kafka version be choosing the desired version of Confluent Platform:
+   * [[https://hub.docker.com/r/confluentinc/cp-kafka/tags Available Docker images]],
+   * [[https://docs.confluent.io/current/installation/versions-interoperability.html Kafka versions in Confluent Platform]]
+   */
+  def confluentPlatformVersion: String = TestcontainersKafkaHelper.ConfluentPlatformVersionDefault
+
+  /**
+   * Override this to configure the Kafka container before it is started.
+   */
+  def configureKafka(kafkaContainer: KafkaContainer): Unit = ()
+
+  override def setUp(): Unit = {
+    startKafka(confluentPlatformVersion)
+    super.setUp()
+  }
+
+  override def cleanUp(): Unit = {
+    super.cleanUp()
+    stopKafka()
+  }
+
+}