RankingsTest.java

package storm.starter.tools;

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

import java.util.List;

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

import com.google.common.collect.Lists;

public class RankingsTest {

    private static final int ANY_TOPN = 42;
    private static final Rankable ANY_RANKABLE = new RankableObjectWithFields("someObject", ANY_TOPN);
    private static final Rankable A = new RankableObjectWithFields("A", 1);
    private static final Rankable B = new RankableObjectWithFields("B", 2);
    private static final Rankable C = new RankableObjectWithFields("C", 3);
    private static final Rankable D = new RankableObjectWithFields("D", 4);
    private static final Rankable E = new RankableObjectWithFields("E", 5);
    private static final Rankable F = new RankableObjectWithFields("F", 6);
    private static final Rankable G = new RankableObjectWithFields("G", 7);
    private static final Rankable H = new RankableObjectWithFields("H", 8);

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

    @Test(expectedExceptions = IllegalArgumentException.class, dataProvider = "illegalTopNData")
    public void constructorWithNegativeOrZeroTopNShouldThrowIAE(int topN) {
        new Rankings(topN);
    }

    @DataProvider
    public Object[][] legalTopNData() {
        return new Object[][] { { 1 }, { 2 }, { 1000 }, { 1000000 } };
    }

    @Test(dataProvider = "legalTopNData")
    public void constructorWithPositiveTopNShouldBeOk(int topN) {
        // given/when
        Rankings rankings = new Rankings(topN);

        // then
        assertThat(rankings.maxSize()).isEqualTo(topN);
    }

    @Test
    public void shouldHaveDefaultConstructor() {
        new Rankings();
    }

    @Test
    public void defaultConstructorShouldSetPositiveTopN() {
        // given/when
        Rankings rankings = new Rankings();

        // then
        assertThat(rankings.maxSize()).isGreaterThan(0);
    }

    @DataProvider
    public Object[][] rankingsGrowData() {
        return new Object[][] {
                {
                        2,
                        Lists.newArrayList(new RankableObjectWithFields("A", 1), new RankableObjectWithFields("B", 2),
                            new RankableObjectWithFields("C", 3)) },
                {
                        2,
                        Lists.newArrayList(new RankableObjectWithFields("A", 1), new RankableObjectWithFields("B", 2),
                            new RankableObjectWithFields("C", 3), new RankableObjectWithFields("D", 4)) } };
    }

    @Test(dataProvider = "rankingsGrowData")
    public void sizeOfRankingsShouldNotGrowBeyondTopN(int topN, List<Rankable> rankables) {
        // sanity check of the provided test data
        assertThat(rankables.size()).overridingErrorMessage(
            "The supplied test data is not correct: the number of rankables <%d> should be greater than <%d>",
            rankables.size(), topN).isGreaterThan(topN);

        // given
        Rankings rankings = new Rankings(topN);

        // when
        for (Rankable r : rankables) {
            rankings.updateWith(r);
        }

        // then
        assertThat(rankings.size()).isLessThanOrEqualTo(rankings.maxSize());
    }

    @DataProvider
    public Object[][] simulatedRankingsData() {
        return new Object[][] {
                { Lists.newArrayList(A), Lists.newArrayList(A) },
                { Lists.newArrayList(B, D, A, C), Lists.newArrayList(D, C, B, A) },
                { Lists.newArrayList(B, F, A, C, D, E), Lists.newArrayList(F, E, D, C, B, A) },
                { Lists.newArrayList(G, B, F, A, C, D, E, H), Lists.newArrayList(H, G, F, E, D, C, B, A) } };
    }

    @Test(dataProvider = "simulatedRankingsData")
    public void shouldCorrectlyRankWhenUpdatedWithRankables(List<Rankable> unsorted, List<Rankable> expSorted) {
        // given
        Rankings rankings = new Rankings(unsorted.size());

        // when
        for (Rankable r : unsorted) {
            rankings.updateWith(r);
        }

        // then
        assertThat(rankings.getRankings()).isEqualTo(expSorted);
    }

    @Test(dataProvider = "simulatedRankingsData")
    public void shouldCorrectlyRankWhenEmptyAndUpdatedWithOtherRankings(List<Rankable> unsorted,
        List<Rankable> expSorted) {
        // given
        Rankings rankings = new Rankings(unsorted.size());
        Rankings otherRankings = new Rankings(rankings.maxSize());
        for (Rankable r : unsorted) {
            otherRankings.updateWith(r);
        }

        // when
        rankings.updateWith(otherRankings);

        // then
        assertThat(rankings.getRankings()).isEqualTo(expSorted);
    }

    @Test(dataProvider = "simulatedRankingsData")
    public void shouldCorrectlyRankWhenUpdatedWithEmptyOtherRankings(List<Rankable> unsorted, List<Rankable> expSorted) {
        // given
        Rankings rankings = new Rankings(unsorted.size());
        for (Rankable r : unsorted) {
            rankings.updateWith(r);
        }
        Rankings emptyRankings = new Rankings(ANY_TOPN);

        // when
        rankings.updateWith(emptyRankings);

        // then
        assertThat(rankings.getRankings()).isEqualTo(expSorted);
    }

    @DataProvider
    public Object[][] simulatedRankingsAndOtherRankingsData() {
        return new Object[][] {
                { Lists.newArrayList(A), Lists.newArrayList(A), Lists.newArrayList(A) },
                { Lists.newArrayList(A, C), Lists.newArrayList(B, D), Lists.newArrayList(D, C, B, A) },
                { Lists.newArrayList(B, F, A), Lists.newArrayList(C, D, E), Lists.newArrayList(F, E, D, C, B, A) },
                {
                        Lists.newArrayList(G, B, F, A, C),
                        Lists.newArrayList(D, E, H),
                        Lists.newArrayList(H, G, F, E, D, C, B, A) } };
    }

    @Test(dataProvider = "simulatedRankingsAndOtherRankingsData")
    public void shouldCorrectlyRankWhenNotEmptyAndUpdatedWithOtherRankings(List<Rankable> unsorted,
        List<Rankable> unsortedForOtherRankings, List<Rankable> expSorted) {
        // given
        Rankings rankings = new Rankings(expSorted.size());
        for (Rankable r : unsorted) {
            rankings.updateWith(r);
        }
        Rankings otherRankings = new Rankings(unsortedForOtherRankings.size());
        for (Rankable r : unsortedForOtherRankings) {
            otherRankings.updateWith(r);
        }

        // when
        rankings.updateWith(otherRankings);

        // then
        assertThat(rankings.getRankings()).isEqualTo(expSorted);
    }

    @DataProvider
    public Object[][] duplicatesData() {
        Rankable A1 = new RankableObjectWithFields("A", 1);
        Rankable A2 = new RankableObjectWithFields("A", 2);
        Rankable A3 = new RankableObjectWithFields("A", 3);
        return new Object[][] {
                { Lists.newArrayList(ANY_RANKABLE, ANY_RANKABLE, ANY_RANKABLE) },
                { Lists.newArrayList(A1, A2, A3) }, };
    }

    @Test(dataProvider = "duplicatesData")
    public void shouldNotRankDuplicateObjectsMoreThanOnce(List<Rankable> duplicates) {
        // given
        Rankings rankings = new Rankings(duplicates.size());

        // when
        for (Rankable r : duplicates) {
            rankings.updateWith(r);
        }

        // then
        assertThat(rankings.size()).isEqualTo(1);
    }
}