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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.kafka.common.telemetry.internals;
  
  import org.apache.kafka.common.telemetry.internals.LastValueTracker.InstantAndValue;
  
  import org.junit.jupiter.api.Test;
  
  import java.time.Instant;
  import java.util.Collections;
  import java.util.Optional;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class LastValueTrackerTest {
  
      private static final MetricKey METRIC_NAME = new MetricKey("test-metric", Collections.emptyMap());
  
      private final Instant instant1 = Instant.now();
      private final Instant instant2 = instant1.plusMillis(1);
  
      @Test
      public void testGetAndSetDouble() {
          LastValueTracker<Double> lastValueTracker = new LastValueTracker<>();
          Optional<InstantAndValue<Double>> result = lastValueTracker.getAndSet(METRIC_NAME, instant1, 1d);
          assertFalse(result.isPresent());
      }
  
      @Test
      public void testGetAndSetDoubleWithTrackedValue() {
          LastValueTracker<Double> lastValueTracker = new LastValueTracker<>();
          lastValueTracker.getAndSet(METRIC_NAME, instant1, 1d);
  
          Optional<InstantAndValue<Double>> result = lastValueTracker
              .getAndSet(METRIC_NAME, instant2, 1000d);
  
          assertTrue(result.isPresent());
          assertEquals(instant1, result.get().getIntervalStart());
          assertEquals(1d, result.get().getValue(), 1e-6);
      }
  
      @Test
      public void testGetAndSetLong() {
          LastValueTracker<Long> lastValueTracker = new LastValueTracker<>();
          Optional<InstantAndValue<Long>> result = lastValueTracker.getAndSet(METRIC_NAME, instant1, 1L);
          assertFalse(result.isPresent());
      }
  
      @Test
      public void testGetAndSetLongWithTrackedValue() {
          LastValueTracker<Long> lastValueTracker = new LastValueTracker<>();
          lastValueTracker.getAndSet(METRIC_NAME, instant1, 2L);
          Optional<InstantAndValue<Long>> result = lastValueTracker
              .getAndSet(METRIC_NAME, instant2, 10000L);
  
          assertTrue(result.isPresent());
          assertEquals(instant1, result.get().getIntervalStart());
          assertEquals(2L, result.get().getValue().longValue());
      }
  
      @Test
      public void testRemove() {
          LastValueTracker<Double> lastValueTracker = new LastValueTracker<>();
          lastValueTracker.getAndSet(METRIC_NAME, instant1, 1d);
  
          assertTrue(lastValueTracker.contains(METRIC_NAME));
  
          InstantAndValue<Double> result = lastValueTracker.remove(METRIC_NAME);
          assertNotNull(result);
          assertEquals(instant1, result.getIntervalStart());
          assertEquals(1d, result.getValue().longValue());
      }
  
      @Test
      public void testRemoveWithNullKey() {
          LastValueTracker<Double> lastValueTracker = new LastValueTracker<>();
          assertThrows(NullPointerException.class, () -> lastValueTracker.remove(null));
      }
  
      @Test
      public void testRemoveWithInvalidKey() {
          LastValueTracker<Double> lastValueTracker = new LastValueTracker<>();
          assertFalse(lastValueTracker.contains(METRIC_NAME));
  
          InstantAndValue<Double> result = lastValueTracker.remove(METRIC_NAME);
          assertNull(result);
      }
  }