content: /*
   * 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.streams.state.internals;
  
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.state.KeyValueStore;
  import org.apache.kafka.test.GenericInMemoryKeyValueStore;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  import static java.util.Arrays.asList;
  import static org.apache.kafka.test.StreamsTestUtils.toListAndCloseIterator;
  import static org.hamcrest.CoreMatchers.equalTo;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class FilteredCacheIteratorTest {
  
      private static final CacheFunction IDENTITY_FUNCTION = new CacheFunction() {
          @Override
          public Bytes key(final Bytes cacheKey) {
              return cacheKey;
          }
  
          @Override
          public Bytes cacheKey(final Bytes key) {
              return key;
          }
      };
  
      private final KeyValueStore<Bytes, LRUCacheEntry> store = new GenericInMemoryKeyValueStore<>("my-store");
      private final KeyValue<Bytes, LRUCacheEntry> firstEntry = KeyValue.pair(Bytes.wrap("a".getBytes()),
                                                                              new LRUCacheEntry("1".getBytes()));
      private final List<KeyValue<Bytes, LRUCacheEntry>> entries = asList(
              firstEntry,
              KeyValue.pair(Bytes.wrap("b".getBytes()),
                            new LRUCacheEntry("2".getBytes())),
              KeyValue.pair(Bytes.wrap("c".getBytes()),
                            new LRUCacheEntry("3".getBytes())));
  
      private FilteredCacheIterator allIterator;
      private FilteredCacheIterator firstEntryIterator;
  
      @BeforeEach
      public void before() {
          store.putAll(entries);
          final HasNextCondition allCondition = Iterator::hasNext;
          allIterator = new FilteredCacheIterator(
              new DelegatingPeekingKeyValueIterator<>("",
                                                      store.all()), allCondition, IDENTITY_FUNCTION);
  
          final HasNextCondition firstEntryCondition = iterator -> iterator.hasNext() && iterator.peekNextKey().equals(firstEntry.key);
          firstEntryIterator = new FilteredCacheIterator(
                  new DelegatingPeekingKeyValueIterator<>("",
                                                          store.all()), firstEntryCondition, IDENTITY_FUNCTION);
  
      }
  
      @Test
      public void shouldAllowEntryMatchingHasNextCondition() {
          final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toListAndCloseIterator(allIterator);
          assertThat(keyValues, equalTo(entries));
      }
  
      @Test
      public void shouldPeekNextKey() {
          while (allIterator.hasNext()) {
              final Bytes nextKey = allIterator.peekNextKey();
              final KeyValue<Bytes, LRUCacheEntry> next = allIterator.next();
              assertThat(next.key, equalTo(nextKey));
          }
      }
  
      @Test
      public void shouldPeekNext() {
          while (allIterator.hasNext()) {
              final KeyValue<Bytes, LRUCacheEntry> peeked = allIterator.peekNext();
              final KeyValue<Bytes, LRUCacheEntry> next = allIterator.next();
              assertThat(peeked, equalTo(next));
          }
      }
  
      @Test
      public void shouldNotHaveNextIfHasNextConditionNotMet() {
          assertTrue(firstEntryIterator.hasNext());
          firstEntryIterator.next();
          assertFalse(firstEntryIterator.hasNext());
      }
  
      @Test
      public void shouldFilterEntriesNotMatchingHasNextCondition() {
          final List<KeyValue<Bytes, LRUCacheEntry>> keyValues = toListAndCloseIterator(firstEntryIterator);
          assertThat(keyValues, equalTo(Collections.singletonList(firstEntry)));
      }
  
      @Test
      public void shouldThrowUnsupportedOperationExceptionOnRemove() {
          assertThrows(UnsupportedOperationException.class, () -> allIterator.remove());
      }
  
  }
  