test/jdk/java/util/TimeZone/Bug6772689.java

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/*
 * @test
 * @bug 6772689 8347841 8347955
 * @summary Test for standard-to-daylight transitions at midnight:
 * date stays on the given day.
 */

import java.time.ZoneId;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import java.util.function.Predicate;
import static java.util.GregorianCalendar.*;

public class Bug6772689 {
    private static final int BEGIN_YEAR = 2035;
    private static final int END_YEAR = BEGIN_YEAR + 28;

    public static void main(String[] args) {
        TimeZone defaultTimeZone = TimeZone.getDefault();
        int errors = 0;

        Calendar cal = new GregorianCalendar(BEGIN_YEAR, MARCH, 1);
        String[] tzids = TimeZone.availableIDs()
                .filter(Predicate.not(ZoneId.SHORT_IDS::containsKey))
                .toArray(String[]::new);
        try {
            for (String id : tzids) {
                TimeZone tz = TimeZone.getTimeZone(id);
                if (!tz.useDaylightTime()) {
                    continue;
                }
                TimeZone.setDefault(tz);

              dateloop:
                // Use future dates because sun.util.calendar.ZoneInfo
                // delegates offset transition calculations to a SimpleTimeZone
                // (after 2038 as of JDK7).
                for (int year = BEGIN_YEAR; year < END_YEAR; year++) {
                    for (int month = MARCH; month <= NOVEMBER; month++) {
                        cal.set(year, month, 1, 15, 0, 0);
                        int maxDom = cal.getActualMaximum(DAY_OF_MONTH);
                        for (int dom = 1; dom <= maxDom; dom++) {
                            Date date = new Date(year - 1900, month, dom);
                            if (date.getYear()+1900 != year
                                || date.getMonth() != month
                                || date.getDate() != dom) {
                                System.err.printf("%s: got %04d-%02d-%02d, expected %04d-%02d-%02d%n",
                                                  id,
                                                  date.getYear() + 1900,
                                                  date.getMonth() + 1,
                                                  date.getDate(),
                                                  year,
                                                  month + 1,
                                                  dom);
                                errors++;
                                break dateloop;
                            }
                        }
                    }
                }
            }
        } finally {
            // Restore the default TimeZone.
            TimeZone.setDefault(defaultTimeZone);
        }
        if (errors > 0) {
            throw new RuntimeException("Transition test failed");
        }
    }
}