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.kstream.internals;
  
  import org.apache.kafka.common.serialization.IntegerSerializer;
  import org.apache.kafka.common.serialization.Serdes;
  import org.apache.kafka.streams.KeyValueTimestamp;
  import org.apache.kafka.streams.StreamsBuilder;
  import org.apache.kafka.streams.TestInputTopic;
  import org.apache.kafka.streams.TopologyTestDriver;
  import org.apache.kafka.streams.kstream.Consumed;
  import org.apache.kafka.streams.kstream.KStream;
  import org.apache.kafka.streams.kstream.ValueMapper;
  import org.apache.kafka.streams.kstream.ValueMapperWithKey;
  import org.apache.kafka.test.MockApiProcessorSupplier;
  import org.apache.kafka.test.StreamsTestUtils;
  
  import org.junit.jupiter.api.Test;
  
  import java.time.Duration;
  import java.time.Instant;
  import java.util.ArrayList;
  import java.util.Properties;
  
  import static org.junit.jupiter.api.Assertions.assertArrayEquals;
  
  public class KStreamFlatMapValuesTest {
      private final String topicName = "topic";
      private final Properties props = StreamsTestUtils.getStreamsConfig(Serdes.Integer(), Serdes.String());
  
      @Test
      public void testFlatMapValues() {
          final StreamsBuilder builder = new StreamsBuilder();
  
          final ValueMapper<Number, Iterable<String>> mapper =
              value -> {
                  final ArrayList<String> result = new ArrayList<>();
                  result.add("v" + value);
                  result.add("V" + value);
                  return result;
              };
  
          final int[] expectedKeys = {0, 1, 2, 3};
  
          final KStream<Integer, Integer> stream = builder.stream(topicName, Consumed.with(Serdes.Integer(), Serdes.Integer()));
          final MockApiProcessorSupplier<Integer, String, Void, Void> supplier = new MockApiProcessorSupplier<>();
          stream.flatMapValues(mapper).process(supplier);
  
          try (final TopologyTestDriver driver = new TopologyTestDriver(builder.build(), props)) {
              final TestInputTopic<Integer, Integer> inputTopic =
                      driver.createInputTopic(topicName, new IntegerSerializer(), new IntegerSerializer(), Instant.ofEpochMilli(0L), Duration.ZERO);
              for (final int expectedKey : expectedKeys) {
                  // passing the timestamp to inputTopic.create to disambiguate the call
                  inputTopic.pipeInput(expectedKey, expectedKey, 0L);
              }
          }
  
          final KeyValueTimestamp[] expected = {new KeyValueTimestamp<>(0, "v0", 0), new KeyValueTimestamp<>(0, "V0", 0),
              new KeyValueTimestamp<>(1, "v1", 0), new KeyValueTimestamp<>(1, "V1", 0),
              new KeyValueTimestamp<>(2, "v2", 0), new KeyValueTimestamp<>(2, "V2", 0),
              new KeyValueTimestamp<>(3, "v3", 0), new KeyValueTimestamp<>(3, "V3", 0)};
  
          assertArrayEquals(expected, supplier.theCapturedProcessor().processed().toArray());
      }
  
  
      @Test
      public void testFlatMapValuesWithKeys() {
          final StreamsBuilder builder = new StreamsBuilder();
  
          final ValueMapperWithKey<Integer, Number, Iterable<String>> mapper =
              (readOnlyKey, value) -> {
                  final ArrayList<String> result = new ArrayList<>();
                  result.add("v" + value);
                  result.add("k" + readOnlyKey);
                  return result;
              };
  
          final int[] expectedKeys = {0, 1, 2, 3};
  
          final KStream<Integer, Integer> stream = builder.stream(topicName, Consumed.with(Serdes.Integer(), Serdes.Integer()));
          final MockApiProcessorSupplier<Integer, String, Void, Void> supplier = new MockApiProcessorSupplier<>();
  
          stream.flatMapValues(mapper).process(supplier);
  
          try (final TopologyTestDriver driver = new TopologyTestDriver(builder.build(), props)) {
              final TestInputTopic<Integer, Integer> inputTopic =
                      driver.createInputTopic(topicName, new IntegerSerializer(), new IntegerSerializer(), Instant.ofEpochMilli(0L), Duration.ZERO);
              for (final int expectedKey : expectedKeys) {
                  // passing the timestamp to inputTopic.create to disambiguate the call
                  inputTopic.pipeInput(expectedKey, expectedKey, 0L);
              }
          }
  
          final KeyValueTimestamp[] expected = {new KeyValueTimestamp<>(0, "v0", 0),
              new KeyValueTimestamp<>(0, "k0", 0),
              new KeyValueTimestamp<>(1, "v1", 0),
              new KeyValueTimestamp<>(1, "k1", 0),
              new KeyValueTimestamp<>(2, "v2", 0),
              new KeyValueTimestamp<>(2, "k2", 0),
              new KeyValueTimestamp<>(3, "v3", 0),
              new KeyValueTimestamp<>(3, "k3", 0)};
  
          assertArrayEquals(expected, supplier.theCapturedProcessor().processed().toArray());
      }
  }
  