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.sdk.transforms;
  
  import static org.apache.beam.sdk.transforms.display.DisplayDataMatchers.hasDisplayItem;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertTrue;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.sdk.coders.CannotProvideCoderException;
  import org.apache.beam.sdk.testing.NeedsRunner;
  import org.apache.beam.sdk.testing.PAssert;
  import org.apache.beam.sdk.testing.TestPipeline;
  import org.apache.beam.sdk.transforms.Partition.PartitionFn;
  import org.apache.beam.sdk.transforms.Partition.PartitionWithSideInputsFn;
  import org.apache.beam.sdk.transforms.display.DisplayData;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionList;
  import org.apache.beam.sdk.values.PCollectionView;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  import org.junit.rules.ExpectedException;
  import org.junit.runner.RunWith;
  import org.junit.runners.JUnit4;
  
  /** Tests for {@link Partition}. */
  @RunWith(JUnit4.class)
  public class PartitionTest implements Serializable {
  
    @Rule public final transient TestPipeline pipeline = TestPipeline.create();
    @Rule public transient ExpectedException thrown = ExpectedException.none();
  
    static class ModFn implements PartitionFn<Integer> {
      @Override
      public int partitionFor(Integer elem, int numPartitions) {
        return elem % numPartitions;
      }
    }
  
    static class IdentityFn implements PartitionFn<Integer> {
      @Override
      public int partitionFor(Integer elem, int numPartitions) {
        return elem;
      }
    }
  
    static class IdentitySideViewFn implements PartitionWithSideInputsFn<Integer> {
      @Override
      public int partitionFor(Integer elem, int numPartitions, Contextful.Fn.Context c) {
        return elem;
      }
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testPartitionWithSideInputs() {
  
      PCollectionView<Integer> gradesView =
          pipeline.apply("grades", Create.of(50)).apply(View.asSingleton());
  
      Create.Values<Integer> studentsPercentage = Create.of(5, 45, 90, 29, 55, 65);
      PCollectionList<Integer> studentsGrades =
          pipeline
              .apply(studentsPercentage)
              .apply(
                  Partition.of(
                      2,
                      (elem, numPartitions, ct) -> {
                        Integer grades = ct.sideInput(gradesView);
                        return elem < grades ? 0 : 1;
                      },
                      Requirements.requiresSideInputs(gradesView)));
  
      assertTrue(studentsGrades.size() == 2);
      PAssert.that(studentsGrades.get(0)).containsInAnyOrder(5, 29, 45);
      PAssert.that(studentsGrades.get(1)).containsInAnyOrder(55, 65, 90);
      pipeline.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testEvenOddPartition() {
  
      PCollectionList<Integer> outputs =
          pipeline
              .apply(Create.of(591, 11789, 1257, 24578, 24799, 307))
              .apply(Partition.of(2, new ModFn()));
      assertTrue(outputs.size() == 2);
      PAssert.that(outputs.get(0)).containsInAnyOrder(24578);
      PAssert.that(outputs.get(1)).containsInAnyOrder(591, 11789, 1257, 24799, 307);
      pipeline.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testModPartition() {
  
      PCollectionList<Integer> outputs =
          pipeline.apply(Create.of(1, 2, 4, 5)).apply(Partition.of(3, new ModFn()));
      assertTrue(outputs.size() == 3);
      PAssert.that(outputs.get(0)).empty();
      PAssert.that(outputs.get(1)).containsInAnyOrder(1, 4);
      PAssert.that(outputs.get(2)).containsInAnyOrder(2, 5);
      pipeline.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testOutOfBoundsPartitions() {
  
      pipeline.apply(Create.of(-1)).apply(Partition.of(5, new IdentityFn()));
  
      thrown.expect(RuntimeException.class);
      thrown.expectMessage("Partition function returned out of bounds index: -1 not in [0..5)");
      pipeline.run();
    }
  
    @Test
    public void testZeroNumPartitions() {
  
      PCollection<Integer> input = pipeline.apply(Create.of(591));
  
      thrown.expect(IllegalArgumentException.class);
      thrown.expectMessage("numPartitions must be > 0");
      input.apply(Partition.of(0, new IdentityFn()));
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testDroppedPartition() {
  
      // Compute the set of integers either 1 or 2 mod 3, the hard way.
      PCollectionList<Integer> outputs =
          pipeline
              .apply(Create.of(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12))
              .apply(Partition.of(3, new ModFn()));
  
      List<PCollection<Integer>> outputsList = new ArrayList<>(outputs.getAll());
      outputsList.remove(0);
      outputs = PCollectionList.of(outputsList);
      assertTrue(outputs.size() == 2);
  
      PCollection<Integer> output = outputs.apply(Flatten.pCollections());
      PAssert.that(output).containsInAnyOrder(2, 4, 5, 7, 8, 10, 11);
      pipeline.run();
    }
  
    @Test
    public void testPartitionGetName() {
      assertEquals("Partition", Partition.of(3, new ModFn()).getName());
    }
  
    @Test
    public void testDisplayData() {
      Partition<?> partition = Partition.of(123, new IdentityFn());
      DisplayData displayData = DisplayData.from(partition);
  
      assertThat(displayData, hasDisplayItem("numPartitions", 123));
      assertThat(displayData, hasDisplayItem("partitionFn", IdentityFn.class));
    }
  
    @Test
    public void testDisplayDataOfSideViewFunction() {
      Partition<?> partition = Partition.of(123, new IdentitySideViewFn(), Requirements.empty());
      DisplayData displayData = DisplayData.from(partition);
  
      assertThat(displayData, hasDisplayItem("numPartitions", 123));
      assertThat(displayData, hasDisplayItem("partitionFn", IdentitySideViewFn.class));
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testModPartitionWithLambda() {
  
      PCollectionList<Integer> outputs =
          pipeline
              .apply(Create.of(1, 2, 4, 5))
              .apply(Partition.of(3, (element, numPartitions) -> element % numPartitions));
      assertEquals(3, outputs.size());
      PAssert.that(outputs.get(0)).empty();
      PAssert.that(outputs.get(1)).containsInAnyOrder(1, 4);
      PAssert.that(outputs.get(2)).containsInAnyOrder(2, 5);
      pipeline.run();
    }
  
    /**
     * Confirms that in Java 8 style, where a lambda results in a rawtype, the output type token is
     * not useful. If this test ever fails there may be simplifications available to us.
     */
    @Test
    @Category(NeedsRunner.class)
    public void testPartitionFnOutputTypeDescriptorRaw() throws Exception {
  
      PCollectionList<String> output =
          pipeline.apply(Create.of("hello")).apply(Partition.of(1, (element, numPartitions) -> 0));
  
      thrown.expect(CannotProvideCoderException.class);
      pipeline.getCoderRegistry().getCoder(output.get(0).getTypeDescriptor());
    }
  }
  