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 java.io.Serializable;
  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.display.DisplayData;
  import org.apache.beam.sdk.values.PCollection;
  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 Filter}. */
  @RunWith(JUnit4.class)
  public class FilterTest implements Serializable {
  
    static class TrivialFn implements SerializableFunction<Integer, Boolean> {
      private final Boolean returnVal;
  
      TrivialFn(Boolean returnVal) {
        this.returnVal = returnVal;
      }
  
      @Override
      public Boolean apply(Integer elem) {
        return this.returnVal;
      }
    }
  
    static class EvenFn implements SerializableFunction<Integer, Boolean> {
      @Override
      public Boolean apply(Integer elem) {
        return elem % 2 == 0;
      }
    }
  
    static class EvenProcessFn implements ProcessFunction<Integer, Boolean> {
      @Override
      public Boolean apply(Integer elem) throws Exception {
        return elem % 2 == 0;
      }
    }
  
    @Rule public final TestPipeline p = TestPipeline.create();
  
    @Rule public transient ExpectedException thrown = ExpectedException.none();
  
    @Test
    @Category(NeedsRunner.class)
    public void testIdentityFilterByPredicate() {
      PCollection<Integer> output =
          p.apply(Create.of(591, 11789, 1257, 24578, 24799, 307))
              .apply(Filter.by(new TrivialFn(true)));
  
      PAssert.that(output).containsInAnyOrder(591, 11789, 1257, 24578, 24799, 307);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testNoFilterByPredicate() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 4, 5)).apply(Filter.by(new TrivialFn(false)));
  
      PAssert.that(output).empty();
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterByPredicate() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.by(new EvenFn()));
  
      PAssert.that(output).containsInAnyOrder(2, 4, 6);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterByProcessFunction() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.by(new EvenProcessFn()));
  
      PAssert.that(output).containsInAnyOrder(2, 4, 6);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterLessThan() {
      PCollection<Integer> output = p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.lessThan(4));
  
      PAssert.that(output).containsInAnyOrder(1, 2, 3);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterGreaterThan() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.greaterThan(4));
  
      PAssert.that(output).containsInAnyOrder(5, 6, 7);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterLessThanEq() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.lessThanEq(4));
  
      PAssert.that(output).containsInAnyOrder(1, 2, 3, 4);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterGreaterThanEq() {
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.greaterThanEq(4));
  
      PAssert.that(output).containsInAnyOrder(4, 5, 6, 7);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterEqual() {
      PCollection<Integer> output = p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.equal(4));
  
      PAssert.that(output).containsInAnyOrder(4);
      p.run();
    }
  
    @Test
    public void testDisplayData() {
      assertThat(DisplayData.from(Filter.lessThan(123)), hasDisplayItem("predicate", "x < 123"));
  
      assertThat(DisplayData.from(Filter.lessThanEq(234)), hasDisplayItem("predicate", "x ≤ 234"));
  
      assertThat(DisplayData.from(Filter.greaterThan(345)), hasDisplayItem("predicate", "x > 345"));
  
      assertThat(DisplayData.from(Filter.greaterThanEq(456)), hasDisplayItem("predicate", "x ≥ 456"));
  
      assertThat(DisplayData.from(Filter.equal(567)), hasDisplayItem("predicate", "x == 567"));
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testIdentityFilterByPredicateWithLambda() {
  
      PCollection<Integer> output =
          p.apply(Create.of(591, 11789, 1257, 24578, 24799, 307)).apply(Filter.by(i -> true));
  
      PAssert.that(output).containsInAnyOrder(591, 11789, 1257, 24578, 24799, 307);
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testNoFilterByPredicateWithLambda() {
  
      PCollection<Integer> output = p.apply(Create.of(1, 2, 4, 5)).apply(Filter.by(i -> false));
  
      PAssert.that(output).empty();
      p.run();
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterByPredicateWithLambda() {
  
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.by(i -> i % 2 == 0));
  
      PAssert.that(output).containsInAnyOrder(2, 4, 6);
      p.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
    public void testFilterParDoOutputTypeDescriptorRawWithLambda() throws Exception {
  
      @SuppressWarnings({"unchecked", "rawtypes"})
      PCollection<String> output = p.apply(Create.of("hello")).apply(Filter.by(s -> true));
  
      thrown.expect(CannotProvideCoderException.class);
      p.getCoderRegistry().getCoder(output.getTypeDescriptor());
    }
  
    @Test
    @Category(NeedsRunner.class)
    public void testFilterByMethodReferenceWithLambda() {
  
      PCollection<Integer> output =
          p.apply(Create.of(1, 2, 3, 4, 5, 6, 7)).apply(Filter.by(new EvenFilter()::isEven));
  
      PAssert.that(output).containsInAnyOrder(2, 4, 6);
      p.run();
    }
  
    private static class EvenFilter implements Serializable {
      public boolean isEven(int i) {
        return i % 2 == 0;
      }
    }
  }
  