/*
 * 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.hudi.common.util.collection;

import org.junit.jupiter.api.Test;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

import static org.apache.hudi.common.util.CollectionUtils.toStream;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class TestIterators {

  @Test
  public void testFlatteningIterator() {
    List<List<Integer>> listOfList =
        Arrays.asList(
            Arrays.asList(0),
            Arrays.asList(1, 2),
            Collections.emptyList(),
            Arrays.asList(3, 4, 5)
        );

    List<Integer> flattenedList =
        toStream(new FlatteningIterator<>(new MappingIterator<>(listOfList.iterator(), List::iterator)))
            .collect(Collectors.toList());

    assertEquals(Arrays.asList(0, 1, 2, 3, 4, 5), flattenedList);
  }
}
