/*
 * 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.flink.runtime.checkpoint;

import org.junit.Test;

import java.util.concurrent.ThreadLocalRandom;

import static org.junit.Assert.assertEquals;

public class MinMaxAvgStatsTest {

	/**
	 * Test the initial/empty state.
	 */
	@Test
	public void testInitialState() throws Exception {
		MinMaxAvgStats mma = new MinMaxAvgStats();

		assertEquals(0, mma.getMinimum());
		assertEquals(0, mma.getMaximum());
		assertEquals(0, mma.getSum());
		assertEquals(0, mma.getCount());
		assertEquals(0, mma.getAverage());
	}

	/**
	 * Test that non-positive numbers are not counted.
	 */
	@Test
	public void testAddNonPositiveStats() throws Exception {
		MinMaxAvgStats mma = new MinMaxAvgStats();
		mma.add(-1);

		assertEquals(0, mma.getMinimum());
		assertEquals(0, mma.getMaximum());
		assertEquals(0, mma.getSum());
		assertEquals(0, mma.getCount());
		assertEquals(0, mma.getAverage());

		mma.add(0);

		assertEquals(0, mma.getMinimum());
		assertEquals(0, mma.getMaximum());
		assertEquals(0, mma.getSum());
		assertEquals(1, mma.getCount());
		assertEquals(0, mma.getAverage());
	}

	/**
	 * Test sequence of random numbers.
	 */
	@Test
	public void testAddRandomNumbers() throws Exception {
		ThreadLocalRandom rand = ThreadLocalRandom.current();

		MinMaxAvgStats mma = new MinMaxAvgStats();

		long count = 13;
		long sum = 0;
		long min = Integer.MAX_VALUE;
		long max = Integer.MIN_VALUE;

		for (int i = 0; i < count; i++) {
			int number = rand.nextInt(124) + 1;
			sum += number;
			min = Math.min(min, number);
			max = Math.max(max, number);

			mma.add(number);
		}

		assertEquals(min, mma.getMinimum());
		assertEquals(max, mma.getMaximum());
		assertEquals(sum, mma.getSum());
		assertEquals(count, mma.getCount());
		assertEquals(sum / count, mma.getAverage());
	}

}