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.Contextful.fn;
  import static org.apache.beam.sdk.transforms.Requirements.requiresSideInputs;
  import static org.apache.beam.sdk.transforms.display.DisplayDataMatchers.hasDisplayItem;
  import static org.apache.beam.sdk.values.TypeDescriptors.integers;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.Matchers.equalTo;
  
  import java.io.Serializable;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  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.Contextful.Fn;
  import org.apache.beam.sdk.transforms.FlatMapElements.FlatMapWithFailures;
  import org.apache.beam.sdk.transforms.WithFailures.ExceptionAsMapHandler;
  import org.apache.beam.sdk.transforms.WithFailures.ExceptionElement;
  import org.apache.beam.sdk.transforms.WithFailures.Result;
  import org.apache.beam.sdk.transforms.display.DisplayData;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionView;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.apache.beam.sdk.values.TypeDescriptors;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableSet;
  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 FlatMapElements}. */
  @RunWith(JUnit4.class)
  public class FlatMapElementsTest implements Serializable {
  
    @Rule public final transient TestPipeline pipeline = TestPipeline.create();
  
    @Rule public transient ExpectedException thrown = ExpectedException.none();
  
    /** Basic test of {@link FlatMapElements} with a {@link SimpleFunction}. */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapSimpleFunction() throws Exception {
      PCollection<Integer> output =
          pipeline
              .apply(Create.of(1, 2, 3))
  
              // Note that FlatMapElements takes an InferableFunction<InputT, ? extends
              // Iterable<OutputT>>
              // so the use of List<Integer> here (as opposed to Iterable<Integer>) deliberately
              // exercises
              // the use of an upper bound.
              .apply(
                  FlatMapElements.via(
                      new SimpleFunction<Integer, List<Integer>>() {
                        @Override
                        public List<Integer> apply(Integer input) {
                          return ImmutableList.of(-input, input);
                        }
                      }));
  
      PAssert.that(output).containsInAnyOrder(1, -2, -1, -3, 2, 3);
      pipeline.run();
    }
  
    /** Basic test of {@link FlatMapElements} with an {@link InferableFunction}. */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapInferableFunction() throws Exception {
      PCollection<Integer> output =
          pipeline
              .apply(Create.of(1, 2, 3))
              .apply(
                  FlatMapElements.via(
                      new InferableFunction<Integer, List<Integer>>() {
                        @Override
                        public List<Integer> apply(Integer input) throws Exception {
                          return ImmutableList.of(-input, input);
                        }
                      }));
  
      PAssert.that(output).containsInAnyOrder(1, -2, -1, -3, 2, 3);
      pipeline.run();
    }
  
    /** Basic test of {@link FlatMapElements} with a {@link Fn} and a side input. */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapBasicWithSideInput() throws Exception {
      final PCollectionView<Integer> view =
          pipeline.apply("Create base", Create.of(40)).apply(View.asSingleton());
      PCollection<Integer> output =
          pipeline
              .apply(Create.of(0, 1, 2))
              .apply(
                  FlatMapElements.into(integers())
                      .via(
                          fn(
                              (input, c) ->
                                  ImmutableList.of(
                                      c.sideInput(view) - input, c.sideInput(view) + input),
                              requiresSideInputs(view))));
  
      PAssert.that(output).containsInAnyOrder(38, 39, 40, 40, 41, 42);
      pipeline.run();
    }
  
    /**
     * Tests that when built with a concrete subclass of {@link SimpleFunction}, the type descriptor
     * of the output reflects its static type.
     */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapFnOutputTypeDescriptor() throws Exception {
      PCollection<String> output =
          pipeline
              .apply(Create.of("hello"))
              .apply(
                  FlatMapElements.via(
                      new SimpleFunction<String, Set<String>>() {
                        @Override
                        public Set<String> apply(String input) {
                          return ImmutableSet.copyOf(input.split(""));
                        }
                      }));
  
      assertThat(
          output.getTypeDescriptor(),
          equalTo((TypeDescriptor<String>) new TypeDescriptor<String>() {}));
      assertThat(
          pipeline.getCoderRegistry().getCoder(output.getTypeDescriptor()),
          equalTo(pipeline.getCoderRegistry().getCoder(new TypeDescriptor<String>() {})));
  
      // Make sure the pipeline runs
      pipeline.run();
    }
  
    /**
     * A {@link SimpleFunction} to test that the coder registry can propagate coders that are bound to
     * type variables.
     */
    private static class PolymorphicSimpleFunction<T> extends SimpleFunction<T, Iterable<T>> {
      @Override
      public Iterable<T> apply(T input) {
        return Collections.emptyList();
      }
    }
  
    /**
     * Basic test of {@link MapElements} coder propagation with a parametric {@link SimpleFunction}.
     */
    @Test
    public void testPolymorphicSimpleFunction() throws Exception {
      pipeline.enableAbandonedNodeEnforcement(false);
  
      pipeline
          .apply(Create.of(1, 2, 3))
  
          // This is the function that needs to propagate the input T to output T
          .apply("Polymorphic Identity", MapElements.via(new PolymorphicSimpleFunction<>()))
  
          // This is a consumer to ensure that all coder inference logic is executed.
          .apply(
              "Test Consumer",
              MapElements.via(
                  new SimpleFunction<Iterable<Integer>, Integer>() {
                    @Override
                    public Integer apply(Iterable<Integer> input) {
                      return 42;
                    }
                  }));
    }
  
    @Test
    public void testSimpleFunctionClassDisplayData() {
      SimpleFunction<Integer, List<Integer>> simpleFn =
          new SimpleFunction<Integer, List<Integer>>() {
            @Override
            public List<Integer> apply(Integer input) {
              return Collections.emptyList();
            }
          };
  
      FlatMapElements<?, ?> simpleMap = FlatMapElements.via(simpleFn);
      assertThat(DisplayData.from(simpleMap), hasDisplayItem("class", simpleFn.getClass()));
    }
  
    @Test
    public void testInferableFunctionClassDisplayData() {
      InferableFunction<Integer, List<Integer>> inferableFn =
          new InferableFunction<Integer, List<Integer>>() {
            @Override
            public List<Integer> apply(Integer input) {
              return Collections.emptyList();
            }
          };
  
      FlatMapElements<?, ?> inferableMap = FlatMapElements.via(inferableFn);
      assertThat(DisplayData.from(inferableMap), hasDisplayItem("class", inferableFn.getClass()));
    }
  
    @Test
    public void testSimpleFunctionDisplayData() {
      SimpleFunction<Integer, List<Integer>> simpleFn =
          new SimpleFunction<Integer, List<Integer>>() {
            @Override
            public List<Integer> apply(Integer input) {
              return Collections.emptyList();
            }
  
            @Override
            public void populateDisplayData(DisplayData.Builder builder) {
              builder.add(DisplayData.item("foo", "baz"));
            }
          };
  
      FlatMapElements<?, ?> simpleFlatMap = FlatMapElements.via(simpleFn);
      assertThat(DisplayData.from(simpleFlatMap), hasDisplayItem("class", simpleFn.getClass()));
      assertThat(DisplayData.from(simpleFlatMap), hasDisplayItem("foo", "baz"));
    }
  
    @Test
    public void testInferableFunctionDisplayData() {
      InferableFunction<Integer, List<Integer>> inferableFn =
          new InferableFunction<Integer, List<Integer>>() {
            @Override
            public List<Integer> apply(Integer input) {
              return Collections.emptyList();
            }
  
            @Override
            public void populateDisplayData(DisplayData.Builder builder) {
              builder.add(DisplayData.item("foo", "baz"));
            }
          };
  
      FlatMapElements<?, ?> inferableFlatMap = FlatMapElements.via(inferableFn);
      assertThat(DisplayData.from(inferableFlatMap), hasDisplayItem("class", inferableFn.getClass()));
      assertThat(DisplayData.from(inferableFlatMap), hasDisplayItem("foo", "baz"));
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testVoidValues() throws Exception {
      pipeline
          .apply(Create.of("hello"))
          .apply(WithKeys.of("k"))
          .apply(new VoidValues<String, String>() {});
      // Make sure the pipeline runs
      pipeline.run();
    }
  
    static class VoidValues<K, V>
        extends PTransform<PCollection<KV<K, V>>, PCollection<KV<K, Void>>> {
  
      @Override
      public PCollection<KV<K, Void>> expand(PCollection<KV<K, V>> input) {
        return input.apply(
            FlatMapElements.<KV<K, V>, KV<K, Void>>via(
                new SimpleFunction<KV<K, V>, Iterable<KV<K, Void>>>() {
                  @Override
                  public Iterable<KV<K, Void>> apply(KV<K, V> input) {
                    return Collections.singletonList(KV.<K, Void>of(input.getKey(), null));
                  }
                }));
      }
    }
  
    /**
     * Basic test of {@link FlatMapElements} with a lambda (which is instantiated as a {@link
     * ProcessFunction}).
     */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapBasicWithLambda() throws Exception {
      PCollection<Integer> output =
          pipeline
              .apply(Create.of(1, 2, 3))
              .apply(
                  FlatMapElements
                      // Note that the input type annotation is required.
                      .into(TypeDescriptors.integers())
                      .via((Integer i) -> ImmutableList.of(i, -i)));
  
      PAssert.that(output).containsInAnyOrder(1, 3, -1, -3, 2, -2);
      pipeline.run();
    }
  
    /** Basic test of {@link FlatMapElements} with a method reference. */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapMethodReference() throws Exception {
  
      PCollection<Integer> output =
          pipeline
              .apply(Create.of(1, 2, 3))
              .apply(
                  FlatMapElements
                      // Note that the input type annotation is required.
                      .into(TypeDescriptors.integers())
                      .via(new Negater()::numAndNegation));
  
      PAssert.that(output).containsInAnyOrder(1, 3, -1, -3, 2, -2);
      pipeline.run();
    }
  
    private static class Negater implements Serializable {
      public List<Integer> numAndNegation(int input) {
        return ImmutableList.of(input, -input);
      }
    }
  
    /** Test of {@link FlatMapWithFailures} with a pre-built exception handler. */
    @Test
    @Category(NeedsRunner.class)
    public void testExceptionAsMap() throws Exception {
  
      Result<PCollection<Integer>, KV<Integer, Map<String, String>>> result =
          pipeline
              .apply(Create.of(0, 2, 3))
              .apply(
                  FlatMapElements.into(TypeDescriptors.integers())
                      .via((Integer i) -> ImmutableList.of(i + 1 / i, -i - 1 / i))
                      .exceptionsVia(new ExceptionAsMapHandler<Integer>() {}));
  
      PAssert.that(result.output()).containsInAnyOrder(2, -2, 3, -3);
      pipeline.run();
    }
  
    /** Test of {@link FlatMapWithFailures} with handling defined via lambda expression. */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapWithFailuresLambda() {
      Result<PCollection<Integer>, KV<Integer, String>> result =
          pipeline
              .apply(Create.of(0, 2, 3))
              .apply(
                  FlatMapElements.into(TypeDescriptors.integers())
                      .via((Integer i) -> ImmutableList.of(i + 1 / i, -i - 1 / i))
                      .exceptionsInto(
                          TypeDescriptors.kvs(TypeDescriptors.integers(), TypeDescriptors.strings()))
                      .exceptionsVia(f -> KV.of(f.element(), f.exception().getMessage())));
  
      PAssert.that(result.output()).containsInAnyOrder(2, -2, 3, -3);
      PAssert.that(result.failures()).containsInAnyOrder(KV.of(0, "/ by zero"));
      pipeline.run();
    }
  
    /**
     * Test of {@link FlatMapWithFailures()} with a {@link SimpleFunction} and no {@code into} call.
     */
    @Test
    @Category(NeedsRunner.class)
    public void testFlatMapWithFailuresSimpleFunction() {
      Result<PCollection<Integer>, KV<Integer, String>> result =
          pipeline
              .apply(Create.of(0, 2, 3))
              .apply(
                  FlatMapElements.into(TypeDescriptors.integers())
                      .via((Integer i) -> ImmutableList.of(i + 1 / i, -i - 1 / i))
                      .exceptionsVia(
                          new SimpleFunction<ExceptionElement<Integer>, KV<Integer, String>>() {
                            @Override
                            public KV<Integer, String> apply(ExceptionElement<Integer> failure) {
                              return KV.of(failure.element(), failure.exception().getMessage());
                            }
                          }));
  
      PAssert.that(result.output()).containsInAnyOrder(2, -2, 3, -3);
      PAssert.that(result.failures()).containsInAnyOrder(KV.of(0, "/ by zero"));
  
      pipeline.run();
    }
  
    @Test
    public void testFlatMapWithFailuresDisplayData() {
      InferableFunction<Integer, List<Integer>> inferableFn =
          new InferableFunction<Integer, List<Integer>>() {
            @Override
            public List<Integer> apply(Integer input) {
              return ImmutableList.of(input);
            }
  
            @Override
            public void populateDisplayData(DisplayData.Builder builder) {
              builder.add(DisplayData.item("foo", "baz"));
            }
          };
  
      InferableFunction<ExceptionElement<Integer>, String> exceptionHandler =
          new InferableFunction<ExceptionElement<Integer>, String>() {
            @Override
            public String apply(ExceptionElement<Integer> input) throws Exception {
              return "";
            }
  
            @Override
            public void populateDisplayData(DisplayData.Builder builder) {
              builder.add(DisplayData.item("bar", "buz"));
            }
          };
  
      FlatMapWithFailures<?, ?, ?> mapWithFailures =
          FlatMapElements.via(inferableFn).exceptionsVia(exceptionHandler);
      assertThat(DisplayData.from(mapWithFailures), hasDisplayItem("class", inferableFn.getClass()));
      assertThat(
          DisplayData.from(mapWithFailures),
          hasDisplayItem("exceptionHandler.class", exceptionHandler.getClass()));
      assertThat(DisplayData.from(mapWithFailures), hasDisplayItem("foo", "baz"));
      assertThat(DisplayData.from(mapWithFailures), hasDisplayItem("bar", "buz"));
    }
  }
  