じゃんけんロジック

Janken.java

public class Janken {
    public static class Hand {
        public static final int GU = 0;
        public static final int CHOKI = 1;
        public static final int PA = 2;
    }

    public static class Result {
        public static final int DRAW = 0;
        public static final int WIN = 1;
        public static final int LOSE = 2;
    }

    public static int judge(int one, int another) {
        return (one - another + 3) % 3;
    }
}

JankenTest.java

import org.junit.Test;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

public class JankenTest {
    // tekitou
    
    @Test
    public void testCHOKI_CHOKI() throws Exception {
        assertThat(Janken.judge(Janken.Hand.CHOKI, Janken.Hand.CHOKI), is(Janken.Result.DRAW));
    }

    @Test
    public void testCHOKI_GU() throws Exception {
        assertThat(Janken.judge(Janken.Hand.CHOKI, Janken.Hand.GU), is(Janken.Result.LOSE));
    }

    @Test
    public void testCHOKI_PA() throws Exception {
        assertThat(Janken.judge(Janken.Hand.CHOKI, Janken.Hand.PA), is(Janken.Result.WIN));
    }

    @Test
    public void testGU_CHOKI() throws Exception {
        assertThat(Janken.judge(Janken.Hand.GU, Janken.Hand.CHOKI), is(Janken.Result.WIN));
    }

    @Test
    public void testGU_GU() throws Exception {
        assertThat(Janken.judge(Janken.Hand.GU, Janken.Hand.GU), is(Janken.Result.DRAW));
    }

    @Test
    public void testGU_PA() throws Exception {
        assertThat(Janken.judge(Janken.Hand.GU, Janken.Hand.PA), is(Janken.Result.LOSE));
    }


    @Test
    public void testPA_CHOKI() throws Exception {
        assertThat(Janken.judge(Janken.Hand.PA, Janken.Hand.CHOKI), is(Janken.Result.LOSE));
    }

    @Test
    public void testPA_GU() throws Exception {
        assertThat(Janken.judge(Janken.Hand.PA, Janken.Hand.GU), is(Janken.Result.WIN));
    }

    @Test
    public void testPA_PA() throws Exception {
        assertThat(Janken.judge(Janken.Hand.PA, Janken.Hand.PA), is(Janken.Result.DRAW));
    }
}