test(amber): cover email notification dispatch

amber/src/test/scala/org/apache/texera/web/service/EmailNotificationServiceSpec.scala

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.texera.web.service
+
+import org.apache.texera.amber.engine.architecture.rpc.controlreturns.WorkflowAggregatedState
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+
+import java.util.concurrent.ConcurrentLinkedQueue
+import scala.concurrent.Await
+import scala.concurrent.duration.DurationInt
+import scala.jdk.CollectionConverters._
+
+class EmailNotificationServiceSpec extends AnyFlatSpec with Matchers {
+
+  private val completedState = WorkflowAggregatedState.COMPLETED
+  private val awaitTimeout = 2.seconds
+
+  private class RecordingNotifier(
+      shouldSend: Boolean,
+      failureOnSend: Option[RuntimeException] = None
+  ) extends EmailNotifier {
+    val evaluatedStates = new ConcurrentLinkedQueue[WorkflowAggregatedState]()
+    val sentStates = new ConcurrentLinkedQueue[WorkflowAggregatedState]()
+
+    override def shouldSendEmail(workflowState: WorkflowAggregatedState): Boolean = {
+      evaluatedStates.add(workflowState)
+      shouldSend
+    }
+
+    override def sendStatusEmail(state: WorkflowAggregatedState): Unit = {
+      sentStates.add(state)
+      failureOnSend.foreach(throw _)
+    }
+  }
+
+  private def withService(notifier: EmailNotifier)(test: EmailNotificationService => Unit): Unit = {
+    val service = new EmailNotificationService(notifier)
+    try {
+      test(service)
+    } finally {
+      service.shutdown()
+    }
+  }
+
+  "processEmailNotificationIfNeeded" should "send the exact state when the notifier requests it" in {
+    val notifier = new RecordingNotifier(shouldSend = true)
+
+    withService(notifier) { service =>
+      Await.result(service.processEmailNotificationIfNeeded(completedState), awaitTimeout)
+
+      notifier.evaluatedStates.asScala.toList shouldBe List(completedState)
+      notifier.sentStates.asScala.toList shouldBe List(completedState)
+    }
+  }
+
+  it should "not send an email when the notifier declines it" in {
+    val notifier = new RecordingNotifier(shouldSend = false)
+
+    withService(notifier) { service =>
+      Await.result(service.processEmailNotificationIfNeeded(completedState), awaitTimeout)
+
+      notifier.evaluatedStates.asScala.toList shouldBe List(completedState)
+      notifier.sentStates.asScala.toList shouldBe empty
+    }
+  }
+
+  it should "recover from an exception raised while sending an email" in {
+    val notifier = new RecordingNotifier(
+      shouldSend = true,
+      failureOnSend = Some(new RuntimeException("email provider unavailable"))
+    )
+
+    withService(notifier) { service =>
+      noException should be thrownBy {
+        Await.result(service.processEmailNotificationIfNeeded(completedState), awaitTimeout)
+      }
+
+      notifier.sentStates.asScala.toList shouldBe List(completedState)
+    }
+  }
+}