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.beam.runners.flink.streaming;
  
  import static org.junit.Assert.assertNull;
  
  import java.io.Serializable;
  import org.apache.beam.runners.flink.FlinkPipelineOptions;
  import org.apache.beam.runners.flink.TestFlinkRunner;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.io.GenerateSequence;
  import org.apache.beam.sdk.testing.PAssert;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.GroupByKey;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.transforms.SerializableFunction;
  import org.apache.beam.sdk.transforms.windowing.FixedWindows;
  import org.apache.beam.sdk.transforms.windowing.Window;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.joda.time.Duration;
  import org.joda.time.Instant;
  import org.junit.Test;
  
  /** Tests grouping with null values. */
  public class GroupByWithNullValuesTest implements Serializable {
  
    @Test
    public void testGroupByWithNullValues() {
      FlinkPipelineOptions options = FlinkPipelineOptions.defaults();
  
      options.setRunner(TestFlinkRunner.class);
      options.setStreaming(true);
  
      Pipeline pipeline = Pipeline.create(options);
      PCollection<Integer> result =
          pipeline
              .apply(
                  GenerateSequence.from(0)
                      .to(100)
                      .withTimestampFn(
                          new SerializableFunction<Long, Instant>() {
                            @Override
                            public Instant apply(Long input) {
                              return new Instant(input);
                            }
                          }))
              .apply(Window.into(FixedWindows.of(Duration.millis(10))))
              .apply(
                  ParDo.of(
                      new DoFn<Long, KV<String, Void>>() {
                        @ProcessElement
                        public void processElement(ProcessContext pc) {
                          pc.output(KV.of("hello", null));
                        }
                      }))
              .apply(GroupByKey.create())
              .apply(
                  ParDo.of(
                      new DoFn<KV<String, Iterable<Void>>, Integer>() {
                        @ProcessElement
                        public void processElement(ProcessContext pc) {
                          int count = 0;
                          for (Void aVoid : pc.element().getValue()) {
                            assertNull("Element should be null", aVoid);
                            count++;
                          }
                          pc.output(count);
                        }
                      }));
  
      PAssert.that(result).containsInAnyOrder(10, 10, 10, 10, 10, 10, 10, 10, 10, 10);
  
      pipeline.run();
    }
  }
  