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.spark.io;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.hamcrest.core.Is.is;
  
  import java.io.IOException;
  import java.util.NoSuchElementException;
  import org.apache.beam.runners.core.metrics.MetricsContainerImpl;
  import org.apache.beam.sdk.io.Source;
  import org.joda.time.Instant;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.rules.ExpectedException;
  
  /** Test for {@link SourceRDD.Bounded.ReaderToIteratorAdapter}. */
  public class ReaderToIteratorAdapterTest {
  
    @Rule public ExpectedException exception = ExpectedException.none();
  
    private static class TestReader extends Source.Reader<Integer> {
  
      static final int LIMIT = 4;
      static final int START = 1;
  
      private Integer current = START - 1;
      private boolean closed = false;
      private boolean drained = false;
  
      boolean isClosed() {
        return closed;
      }
  
      @Override
      public boolean start() throws IOException {
        return advance();
      }
  
      @Override
      public boolean advance() throws IOException {
        checkState(!drained && !closed);
        drained = ++current >= LIMIT;
        return !drained;
      }
  
      @Override
      public Integer getCurrent() throws NoSuchElementException {
        checkState(!drained && !closed);
        return current;
      }
  
      @Override
      public Instant getCurrentTimestamp() throws NoSuchElementException {
        checkState(!drained && !closed);
        return Instant.now();
      }
  
      @Override
      public void close() throws IOException {
        checkState(!closed);
        closed = true;
      }
  
      @Override
      public Source<Integer> getCurrentSource() {
        return null;
      }
    }
  
    private final TestReader testReader = new TestReader();
  
    private final SourceRDD.Bounded.ReaderToIteratorAdapter<Integer> readerIterator =
        new SourceRDD.Bounded.ReaderToIteratorAdapter<>(new MetricsContainerImpl(""), testReader);
  
    private void assertReaderRange(final int start, final int end) {
      for (int i = start; i < end; i++) {
        assertThat(readerIterator.next().getValue(), is(i));
      }
    }
  
    @Test
    public void testReaderIsClosedAfterDrainage() throws Exception {
      assertReaderRange(TestReader.START, TestReader.LIMIT);
  
      assertThat(readerIterator.hasNext(), is(false));
  
      // reader is closed only after hasNext realises there are no more elements
      assertThat(testReader.isClosed(), is(true));
    }
  
    @Test
    public void testNextWhenDrainedThrows() throws Exception {
      assertReaderRange(TestReader.START, TestReader.LIMIT);
  
      exception.expect(NoSuchElementException.class);
      readerIterator.next();
    }
  
    @Test
    public void testHasNextIdempotencyCombo() throws Exception {
      assertThat(readerIterator.hasNext(), is(true));
      assertThat(readerIterator.hasNext(), is(true));
  
      assertThat(readerIterator.next().getValue(), is(1));
  
      assertThat(readerIterator.hasNext(), is(true));
      assertThat(readerIterator.hasNext(), is(true));
      assertThat(readerIterator.hasNext(), is(true));
  
      assertThat(readerIterator.next().getValue(), is(2));
      assertThat(readerIterator.next().getValue(), is(3));
  
      // drained
  
      assertThat(readerIterator.hasNext(), is(false));
      assertThat(readerIterator.hasNext(), is(false));
  
      // no next to give
  
      exception.expect(NoSuchElementException.class);
      readerIterator.next();
    }
  }
  