ratis-test/src/test/java/org/apache/ratis/util/TestMinMax.java

/**
 * 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.ratis.util;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.Timeout;

import java.util.ArrayList;
import java.util.List;
import java.util.OptionalLong;
import java.util.concurrent.ThreadLocalRandom;
import java.util.stream.LongStream;

public class TestMinMax {
  @Test
  @Timeout(value = 1000)
  public void testMinMax() {
    runTestMinMax(LongStream.empty());
    runTestMinMax(LongStream.iterate(0, n -> n).limit(10));
    for(int count = 1; count < 10; count++) {
      runTestMinMax(LongStream.iterate(1, n -> n + 1).limit(count));
    }
    for(int count = 1; count < 10; count++) {
      runTestMinMax(LongStream.iterate(0, _dummy -> ThreadLocalRandom.current().nextLong()).limit(count));
    }
  }

  static void runTestMinMax(LongStream stream) {
    final List<Long> list = stream.collect(ArrayList::new, List::add, List::addAll);
    final LongMinMax longMinMax = toLongStream(list).collect(LongMinMax::new, LongMinMax::accumulate, LongMinMax::combine);
    if (longMinMax.isInitialized()) {
      Assertions.assertEquals(toLongStream(list).min().getAsLong(), longMinMax.getMin());
      Assertions.assertEquals(toLongStream(list).max().getAsLong(), longMinMax.getMax());
    } else {
      Assertions.assertEquals(OptionalLong.empty(), toLongStream(list).min());
      Assertions.assertEquals(OptionalLong.empty(), toLongStream(list).max());
    }
  }

  static LongStream toLongStream(List<Long> list) {
    return list.stream().mapToLong(Long::longValue);
  }
}