SlidingWindowCounterTest.java

package storm.starter.tools;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

import java.util.Map;

import static org.fest.assertions.api.Assertions.assertThat;

public class SlidingWindowCounterTest {

  private static final int ANY_WINDOW_LENGTH_IN_SLOTS = 2;
  private static final Object ANY_OBJECT = "ANY_OBJECT";

  @DataProvider
  public Object[][] illegalWindowLengths() {
    return new Object[][]{ { -10 }, { -3 }, { -2 }, { -1 }, { 0 }, { 1 } };
  }

  @Test(expectedExceptions = IllegalArgumentException.class, dataProvider = "illegalWindowLengths")
  public void lessThanTwoSlotsShouldThrowIAE(int windowLengthInSlots) {
    new SlidingWindowCounter<Object>(windowLengthInSlots);
  }

  @DataProvider
  public Object[][] legalWindowLengths() {
    return new Object[][]{ { 2 }, { 3 }, { 20 } };
  }

  @Test(dataProvider = "legalWindowLengths")
  public void twoOrMoreSlotsShouldBeValid(int windowLengthInSlots) {
    new SlidingWindowCounter<Object>(windowLengthInSlots);
  }

  @Test
  public void newInstanceShouldHaveEmptyCounts() {
    // given
    SlidingWindowCounter<Object> counter = new SlidingWindowCounter<Object>(ANY_WINDOW_LENGTH_IN_SLOTS);

    // when
    Map<Object, Long> counts = counter.getCountsThenAdvanceWindow();

    // then
    assertThat(counts).isEmpty();
  }

  @DataProvider
  public Object[][] simulatedCounterIterations() {
    return new Object[][]{ { 2, new int[]{ 3, 2, 0, 0, 1, 0, 0, 0 }, new long[]{ 3, 5, 2, 0, 1, 1, 0, 0 } },
        { 3, new int[]{ 3, 2, 0, 0, 1, 0, 0, 0 }, new long[]{ 3, 5, 5, 2, 1, 1, 1, 0 } },
        { 4, new int[]{ 3, 2, 0, 0, 1, 0, 0, 0 }, new long[]{ 3, 5, 5, 5, 3, 1, 1, 1 } },
        { 5, new int[]{ 3, 2, 0, 0, 1, 0, 0, 0 }, new long[]{ 3, 5, 5, 5, 6, 3, 1, 1 } },
        { 5, new int[]{ 3, 11, 5, 13, 7, 17, 0, 3, 50, 600, 7000 },
            new long[]{ 3, 14, 19, 32, 39, 53, 42, 40, 77, 670, 7653 } }, };
  }

  @Test(dataProvider = "simulatedCounterIterations")
  public void testCounterWithSimulatedRuns(int windowLengthInSlots, int[] incrementsPerIteration,
      long[] expCountsPerIteration) {
    // given
    SlidingWindowCounter<Object> counter = new SlidingWindowCounter<Object>(windowLengthInSlots);
    int numIterations = incrementsPerIteration.length;

    for (int i = 0; i < numIterations; i++) {
      int numIncrements = incrementsPerIteration[i];
      long expCounts = expCountsPerIteration[i];
      // Objects are absent if they were zero both this iteration
      // and the last -- if only this one, we need to report zero.
      boolean expAbsent = ((expCounts == 0) && ((i == 0) || (expCountsPerIteration[i - 1] == 0)));

      // given (for this iteration)
      for (int j = 0; j < numIncrements; j++) {
        counter.incrementCount(ANY_OBJECT);
      }

      // when (for this iteration)
      Map<Object, Long> counts = counter.getCountsThenAdvanceWindow();

      // then (for this iteration)
      if (expAbsent) {
        assertThat(counts).doesNotContainKey(ANY_OBJECT);
      }
      else {
        assertThat(counts.get(ANY_OBJECT)).isEqualTo(expCounts);
      }
    }
  }

}