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 com.alibaba.metrics;
  
  import com.alibaba.metrics.WeightedSnapshot.WeightedSample;
  import org.junit.Test;
  
  import java.io.ByteArrayOutputStream;
  import java.util.ArrayList;
  import java.util.List;
  
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.assertj.core.api.Assertions.offset;
  import static org.mockito.Mockito.spy;
  import static org.mockito.Mockito.when;
  
  public class WeightedSnapshotTest {
  
      static public ArrayList<WeightedSample> WeightedArray(long[] values, double[] weights) {
          if (values.length != weights.length) {
              throw new IllegalArgumentException("Mismatched lengths: " + values.length + " vs " + weights.length);
          }
  
          final ArrayList<WeightedSample> samples = new ArrayList<WeightedSnapshot.WeightedSample>();
          for (int i = 0; i < values.length; i++) {
              samples.add(new WeightedSnapshot.WeightedSample(values[i], weights[i]));
          }
  
          return samples;
      }
  
      private final Snapshot snapshot = new WeightedSnapshot(
              WeightedArray(new long[]{5, 1, 2, 3, 4}, new double[]{1, 2, 3, 2, 2}) );
  
      @Test
      public void smallQuantilesAreTheFirstValue() throws Exception {
          assertThat(snapshot.getValue(0.0))
                  .isEqualTo(1.0, offset(0.1));
      }
  
      @Test
      public void bigQuantilesAreTheLastValue() throws Exception {
          assertThat(snapshot.getValue(1.0))
                  .isEqualTo(5.0, offset(0.1));
      }
  
      @Test(expected = IllegalArgumentException.class)
      public void disallowsNotANumberQuantile() {
          snapshot.getValue( Double.NaN );
      }
  
      @Test(expected = IllegalArgumentException.class)
      public void disallowsNegativeQuantile() {
          snapshot.getValue( -0.5 );
      }
  
      @Test(expected = IllegalArgumentException.class)
      public void disallowsQuantileOverOne() {
          snapshot.getValue( 1.5 );
      }
  
      @Test
      public void hasAMedian() throws Exception {
          assertThat(snapshot.getMedian()).isEqualTo(3.0, offset(0.1));
      }
  
      @Test
      public void hasAp75() throws Exception {
          assertThat(snapshot.get75thPercentile()).isEqualTo(4.0, offset(0.1));
      }
  
      @Test
      public void hasAp95() throws Exception {
          assertThat(snapshot.get95thPercentile()).isEqualTo(5.0, offset(0.1));
      }
  
      @Test
      public void hasAp98() throws Exception {
          assertThat(snapshot.get98thPercentile()).isEqualTo(5.0, offset(0.1));
      }
  
      @Test
      public void hasAp99() throws Exception {
          assertThat(snapshot.get99thPercentile()).isEqualTo(5.0, offset(0.1));
      }
  
      @Test
      public void hasAp999() throws Exception {
          assertThat(snapshot.get999thPercentile()).isEqualTo(5.0, offset(0.1));
      }
  
      @Test
      public void hasValues() throws Exception {
          assertThat(snapshot.getValues())
                  .containsOnly(1, 2, 3, 4, 5);
      }
  
      @Test
      public void hasASize() throws Exception {
          assertThat(snapshot.size())
                  .isEqualTo(5);
      }
  
      @Test
      public void worksWithUnderestimatedCollections() throws Exception {
          final List<WeightedSample> items = spy(WeightedArray(new long[]{5, 1, 2, 3, 4}, new double[]{1, 2, 3, 2, 2}));
          when(items.size()).thenReturn(4, 5);
  
          final Snapshot other = new WeightedSnapshot(items);
  
          assertThat(other.getValues())
                  .containsOnly(1, 2, 3, 4, 5);
      }
  
      @Test
      public void worksWithOverestimatedCollections() throws Exception {
          final List<WeightedSample> items = spy(WeightedArray(new long[]{5, 1, 2, 3, 4}, new double[]{1, 2, 3, 2, 2}));
          when(items.size()).thenReturn(6, 5);
  
          final Snapshot other = new WeightedSnapshot(items);
  
          assertThat(other.getValues())
                  .containsOnly(1, 2, 3, 4, 5);
      }
  
      @Test
      public void dumpsToAStream() throws Exception {
          final ByteArrayOutputStream output = new ByteArrayOutputStream();
  
          snapshot.dump(output);
  
          assertThat(output.toString())
                  .isEqualTo(String.format("1%n2%n3%n4%n5%n"));
      }
  
      @Test
      public void calculatesTheMinimumValue() throws Exception {
          assertThat(snapshot.getMin())
                  .isEqualTo(1);
      }
  
      @Test
      public void calculatesTheMaximumValue() throws Exception {
          assertThat(snapshot.getMax())
                  .isEqualTo(5);
      }
  
      @Test
      public void calculatesTheMeanValue() throws Exception {
          assertThat(snapshot.getMean())
                  .isEqualTo(2.7);
      }
  
      @Test
      public void calculatesTheStdDev() throws Exception {
          assertThat(snapshot.getStdDev())
                  .isEqualTo(1.2688, offset(0.0001));
      }
  
      @Test
      public void calculatesAMinOfZeroForAnEmptySnapshot() throws Exception {
          final Snapshot emptySnapshot = new WeightedSnapshot(
              WeightedArray(new long[]{}, new double[]{}) );
  
          assertThat(emptySnapshot.getMin())
                  .isZero();
      }
  
      @Test
      public void calculatesAMaxOfZeroForAnEmptySnapshot() throws Exception {
          final Snapshot emptySnapshot = new WeightedSnapshot(
              WeightedArray(new long[]{}, new double[]{}) );
  
          assertThat(emptySnapshot.getMax())
                  .isZero();
      }
  
      @Test
      public void calculatesAMeanOfZeroForAnEmptySnapshot() throws Exception {
          final Snapshot emptySnapshot = new WeightedSnapshot(
              WeightedArray(new long[]{}, new double[]{}) );
  
          assertThat(emptySnapshot.getMean())
                  .isZero();
      }
  
      @Test
      public void calculatesAStdDevOfZeroForAnEmptySnapshot() throws Exception {
          final Snapshot emptySnapshot = new WeightedSnapshot(
              WeightedArray(new long[]{}, new double[]{}) );
  
          assertThat(emptySnapshot.getStdDev())
                  .isZero();
      }
  
      @Test
      public void calculatesAStdDevOfZeroForASingletonSnapshot() throws Exception {
          final Snapshot singleItemSnapshot = new WeightedSnapshot(
              WeightedArray(new long[]{ 1 }, new double[]{ 1.0 }) );
  
          assertThat(singleItemSnapshot.getStdDev())
                  .isZero();
      }
  
      @Test
      public void expectNoOverflowForLowWeights() throws Exception {
          final Snapshot scatteredSnapshot = new WeightedSnapshot(
              WeightedArray(
                      new long[]{ 1, 2, 3 },
                      new double[]{ Double.MIN_VALUE, Double.MIN_VALUE, Double.MIN_VALUE }
              )
          );
  
          assertThat(scatteredSnapshot.getMean())
                  .isEqualTo(2);
      }
  
  }
  