MovingAverageTest.java

// =================================================================================================
// Copyright 2011 Twitter, Inc.
// -------------------------------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this work except in compliance with the License.
// You may obtain a copy of the License in the LICENSE file, or 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.twitter.common.stats;

import java.util.List;

import com.google.common.collect.Lists;

import org.junit.Before;
import org.junit.Test;

import com.twitter.common.testing.EasyMockTest;

import static org.easymock.EasyMock.expect;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

/**
 * Test for MovingAverage.
 *
 * @author William Farner
 */
public class MovingAverageTest extends EasyMockTest {

  private Stat<Integer> input;

  @Before
  public void setUp() {
    input = createMock(new Clazz<Stat<Integer>>() {});
  }

  @Test
  public void testEmptySeries() {
    runTest(Lists.<Integer>newArrayList(), Lists.<Double>newArrayList());
  }

  @Test
  public void testConstantValues() {
    runTest(
        Lists.newArrayList( 5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5),
        Lists.newArrayList(5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d, 5d));
  }

  @Test
  public void testLinear() {
    runTest(
        Lists.newArrayList( 1,    2,  3,    4,  5,    6,  7,    8,  9,   10,   11,   12,   13),
        Lists.newArrayList(1d, 1.5d, 2d, 2.5d, 3d, 3.5d, 4d, 4.5d, 5d, 5.5d, 6.5d, 7.5d, 8.5d));
  }

  @Test
  public void testStep() {
    runTest(
        Lists.newArrayList( 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 10, 10, 10, 10, 10),
        Lists.newArrayList(0d, 0d, 0d, 0d, 0d, 0d, 0d, 0d, 0d, 0d, 0d, 1d, 2d, 3d, 4d, 5d));
  }

  private void runTest(List<Integer> inputs, List<Double> expectedOutputs) {
    expect(input.getName()).andReturn("test").atLeastOnce();
    for (int value : inputs) {
      expect(input.read()).andReturn(value);
    }

    control.replay();

    MovingAverage<Integer> movingAvg = MovingAverage.of(input, 10 /* window size */);

    for (double output : expectedOutputs) {
      assertThat(movingAvg.sample(), is(output));
    }
  }
}