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.util.construction;
  
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.emptyIterable;
  
  import java.util.Collections;
  import java.util.Map;
  import org.apache.beam.sdk.io.GenerateSequence;
  import org.apache.beam.sdk.runners.AppliedPTransform;
  import org.apache.beam.sdk.runners.PTransformOverrideFactory.PTransformReplacement;
  import org.apache.beam.sdk.runners.PTransformOverrideFactory.ReplacementOutput;
  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.Flatten;
  import org.apache.beam.sdk.transforms.resourcehints.ResourceHints;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionList;
  import org.apache.beam.sdk.values.PValues;
  import org.apache.beam.sdk.values.TaggedPValue;
  import org.hamcrest.Matchers;
  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 EmptyFlattenAsCreateFactory}. */
  @RunWith(JUnit4.class)
  public class EmptyFlattenAsCreateFactoryTest {
    @Rule public TestPipeline pipeline = TestPipeline.create();
    @Rule public ExpectedException thrown = ExpectedException.none();
  
    private EmptyFlattenAsCreateFactory<Long> factory = EmptyFlattenAsCreateFactory.instance();
  
    @Test
    public void getInputEmptySucceeds() {
      PTransformReplacement<PCollectionList<Long>, PCollection<Long>> replacement =
          factory.getReplacementTransform(
              AppliedPTransform.of(
                  "nonEmptyInput",
                  Collections.emptyMap(),
                  Collections.emptyMap(),
                  Flatten.pCollections(),
                  ResourceHints.create(),
                  pipeline));
      assertThat(replacement.getInput().getAll(), emptyIterable());
    }
  
    @Test
    public void getInputNonEmptyThrows() {
      PCollectionList<Long> nonEmpty =
          PCollectionList.of(pipeline.apply("unbounded", GenerateSequence.from(0)))
              .and(pipeline.apply("bounded", GenerateSequence.from(0).to(100)));
      thrown.expect(IllegalArgumentException.class);
      thrown.expectMessage(nonEmpty.expand().toString());
      thrown.expectMessage(EmptyFlattenAsCreateFactory.class.getSimpleName());
      factory.getReplacementTransform(
          AppliedPTransform.of(
              "nonEmptyInput",
              PValues.expandInput(nonEmpty),
              Collections.emptyMap(),
              Flatten.pCollections(),
              ResourceHints.create(),
              pipeline));
    }
  
    @Test
    public void mapOutputsSucceeds() {
      PCollection<Long> original = pipeline.apply("Original", GenerateSequence.from(0));
      PCollection<Long> replacement = pipeline.apply("Replacement", GenerateSequence.from(0));
      Map<PCollection<?>, ReplacementOutput> mapping =
          factory.mapOutputs(PValues.expandOutput(original), replacement);
  
      assertThat(
          mapping,
          Matchers.hasEntry(
              replacement,
              ReplacementOutput.of(
                  TaggedPValue.ofExpandedValue(original),
                  TaggedPValue.ofExpandedValue(replacement))));
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testOverride() {
      PCollectionList<Long> empty = PCollectionList.empty(pipeline);
      PCollection<Long> emptyFlattened =
          empty.apply(
              factory
                  .getReplacementTransform(
                      AppliedPTransform.of(
                          "nonEmptyInput",
                          Collections.emptyMap(),
                          Collections.emptyMap(),
                          Flatten.pCollections(),
                          ResourceHints.create(),
                          pipeline))
                  .getTransform());
      PAssert.that(emptyFlattened).empty();
      pipeline.run();
    }
  }
  