isleapyear by Java

public class LeapYear {
    public static final int LEAP = 1;
    public static final int COMMON = 0;
    public static int isLeapYear(int d) {
        if(d%400 == 0) return 1;
        if(d%100 == 0) return 0;
        if(d%4 == 0) return 1;
       
        return 0;
    }
}

import org.junit.*;
import static org.junit.Assert.*;
public class LeapYearTest {
    @Test
    public void test_1996_is_leap_year() {
        int actual = LeapYear.isLeapYear(1996);
        assertEquals(LeapYear.LEAP, actual);
    }
    @Test
    public void test_2001_is_common_year() {
        int actual = LeapYear.isLeapYear(2001);
        assertEquals(LeapYear.COMMON, actual);
    }
    @Test
    public void test_1900_is_common_year() {
        int actual = LeapYear.isLeapYear(1900);
        assertEquals(LeapYear.COMMON, actual);
    }
    @Test
    public void test_2000_is_leap_year() {
        int actual = LeapYear.isLeapYear(2000);
        assertEquals(LeapYear.LEAP, actual);
    }

}