/*
    * 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
    *
    *      https://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.commons.lang3.concurrent;
  
  import static org.apache.commons.lang3.LangAssertions.assertNullPointerException;
  import static org.junit.jupiter.api.Assertions.assertEquals;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.lang3.AbstractLangTest;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test class for {@code CallableBackgroundInitializer}
   */
  class CallableBackgroundInitializerTest extends AbstractLangTest {
  
      /**
       * A test Callable implementation for checking the initializer's
       * implementation of the initialize() method.
       */
      private static final class TestCallable implements Callable<Integer> {
  
          /** A counter for the number of call() invocations. */
          int callCount;
  
          /**
           * Records this invocation and returns the test result.
           */
          @Override
          public Integer call() {
              callCount++;
              return RESULT;
          }
      }
  
      /** Constant for the result of the call() invocation. */
      private static final Integer RESULT = Integer.valueOf(42);
  
      /**
       * Tests whether the executor service is correctly passed to the super
       * class.
       */
      @Test
      void testInitExecutor() throws InterruptedException {
          final ExecutorService exec = Executors.newSingleThreadExecutor();
          final CallableBackgroundInitializer<Integer> init = new CallableBackgroundInitializer<>(
                  new TestCallable(), exec);
          assertEquals(exec, init.getExternalExecutor(), "Executor not set");
          exec.shutdown();
          exec.awaitTermination(1, TimeUnit.SECONDS);
      }
  
      /**
       * Tries to pass a null Callable to the constructor that takes an executor.
       * This should cause an exception.
       */
      @Test
      void testInitExecutorNullCallable() throws InterruptedException {
          final ExecutorService exec = Executors.newSingleThreadExecutor();
          try {
              assertNullPointerException(() -> new CallableBackgroundInitializer<Integer>(null, exec));
          } finally {
              exec.shutdown();
              exec.awaitTermination(1, TimeUnit.SECONDS);
          }
  
      }
  
      /**
       * Tests the implementation of initialize().
       *
       * @throws Exception so we don't have to catch it
       */
      @Test
      void testInitialize() throws Exception {
          final TestCallable call = new TestCallable();
          final CallableBackgroundInitializer<Integer> init = new CallableBackgroundInitializer<>(
                  call);
          assertEquals(RESULT, init.initialize(), "Wrong result");
          assertEquals(1, call.callCount, "Wrong number of invocations");
      }
 
     /**
      * Tries to create an instance without a Callable. This should cause an
      * exception.
      */
     @Test()
     void testInitNullCallable() {
         assertNullPointerException(() -> new CallableBackgroundInitializer<>(null));
     }
 }