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[LOG4J2-issue-3660] Add comprehensive unit tests for CronExpression daylight saving and scheduling logic #4081

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[LOG4J2-issue-3660] Add comprehensive unit tests for CronExpression daylight saving and scheduling logic #4081

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127 changes: 126 additions & 1 deletion log4j-core-test/src/test/java/org/apache/logging/log4j/core/util/CronExpressionTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,12 +16,21 @@
*/
package org.apache.logging.log4j.core.util;

import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.jupiter.api.Assertions.assertEquals;

import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import org.assertj.core.presentation.Representation;
import org.assertj.core.presentation.StandardRepresentation;
import org.junit.jupiter.api.Test;

/**
Expand Down Expand Up @@ -171,4 +180,120 @@ void testTimeBeforeMilliseconds() throws Exception {
final Date expected = new GregorianCalendar(2015, 10, 1, 0, 0, 0).getTime();
assertEquals(expected, fireDate, "Dates not equal.");
}
}

/**
* Test that the next valid time after a fallback at 2:00 am from Daylight Saving Time
*/
@Test
void daylightSavingChangeAtTwoAm() throws Exception {
ZoneId zoneId = ZoneId.of("Australia/Sydney");
Representation representation = new ZoneOffsetRepresentation(ZoneOffset.ofHours(11));
// The beginning of the day when daylight saving time ends in Australia in 2025 (switch from UTC+11 to UTC+10).
Instant april5 =
ZonedDateTime.of(2025, 4, 4, 13, 0, 0, 0, ZoneOffset.UTC).toInstant();
Instant april6 = april5.plus(24, ChronoUnit.HOURS);
Instant april7 = april6.plus(25, ChronoUnit.HOURS);

final CronExpression expression = new CronExpression("0 0 0 * * ?");
expression.setTimeZone(TimeZone.getTimeZone(zoneId));
// Check the next valid time after 23:59:59.999 on the day before DST ends.
Date currentTime = Date.from(april6.minusMillis(1));
Instant previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(april5);
Instant nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(april6);
// Check the next valid time after 00:00:00.001 on the day DST ends.
currentTime = Date.from(april6.plusMillis(1));
previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(april6);
nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(april7);
}

/**
* Test that the next valid time after a fallback at 0:00 am from Daylight Saving Time
*/
@Test
void daylightSavingChangeAtMidnight() throws Exception {
ZoneId zoneId = ZoneId.of("America/Santiago");
Representation representation = new ZoneOffsetRepresentation(ZoneOffset.ofHours(-3));
// The beginning of the day when daylight saving time ends in Chile in 2025 (switch from UTC-3 to UTC-4).
Instant april5 =
ZonedDateTime.of(2025, 4, 5, 3, 0, 0, 0, ZoneOffset.UTC).toInstant();
// Midnight according to Daylight Saving Time.
Instant april6Dst = april5.plus(24, ChronoUnit.HOURS);
// Midnight according to Standard Time.
Instant april6 = april6Dst.plus(1, ChronoUnit.HOURS);
Instant april7 = april6.plus(24, ChronoUnit.HOURS);

final CronExpression expression = new CronExpression("0 0 0 * * ?");
expression.setTimeZone(TimeZone.getTimeZone(zoneId));
// Check the next valid time after 23:59:59.999 DST (22:59.59.999 standard) on the day before DST ends.
Date currentTime = Date.from(april6Dst.minusMillis(1));
Instant previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(april5);
Instant nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(april6);
// Check the next valid time after 23:59:59.999 on the day before DST ends.
currentTime = Date.from(april6.minusMillis(1));
previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(april5);
nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(april6);
// Check the next valid time after 00:00:00.001 on the day DST ends.
currentTime = Date.from(april6.plusMillis(1));
previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(april6);
nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(april7);
}

/**
* Test that the next valid time after a spring forward (23-hour day) is correct.
* Sydney spring-forward: Oct 5 2025 02:00 UTC+10 → 03:00 UTC+11. Day is only 23 hours long.
*/
@Test
void daylightSavingSpringForward() throws Exception {
ZoneId zoneId = ZoneId.of("Australia/Sydney");
Representation representation = new ZoneOffsetRepresentation(ZoneOffset.ofHours(10));
// Midnight UTC+10 on Oct 5 (the spring-forward day; clocks jump at 2AM → day is 23h).
Instant oct5 = ZonedDateTime.of(2025, 10, 4, 14, 0, 0, 0, ZoneOffset.UTC).toInstant();
// Next midnight is only 23 hours later (UTC+11 offset after the jump).
Instant oct6 = oct5.plus(23, ChronoUnit.HOURS);
Instant oct7 = oct6.plus(24, ChronoUnit.HOURS);

final CronExpression expression = new CronExpression("0 0 0 * * ?");
expression.setTimeZone(TimeZone.getTimeZone(zoneId));

// Check the next valid time after 23:59:59.999 on the spring-forward day.
Date currentTime = Date.from(oct6.minusMillis(1));
Instant previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(oct5);
Instant nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(oct6);

// Check the next valid time after 00:00:00.001 on the day after spring-forward.
currentTime = Date.from(oct6.plusMillis(1));
previousTime = expression.getPrevFireTime(currentTime).toInstant();
assertThat(previousTime).withRepresentation(representation).isEqualTo(oct6);
nextTime = expression.getNextValidTimeAfter(currentTime).toInstant();
assertThat(nextTime).withRepresentation(representation).isEqualTo(oct7);
}

private static class ZoneOffsetRepresentation extends StandardRepresentation {

private final ZoneOffset zoneOffset;

private ZoneOffsetRepresentation(final ZoneOffset zoneOffset) {
this.zoneOffset = zoneOffset;
}

@Override
public String toStringOf(final Object object) {
if (object instanceof Instant) {
return ZonedDateTime.ofInstant((Instant) object, zoneOffset).toString();
}
return super.toStringOf(object);
}
}
}
9 changes: 8 additions & 1 deletion log4j-core/src/main/java/org/apache/logging/log4j/core/util/CronExpression.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1591,6 +1591,11 @@ protected Date getTimeBefore(final Date targetDate) {
}

public Date getPrevFireTime(final Date targetDate) {
// Cron expressions have second precision. If the input has a millisecond fraction,
// include fire times at that same wall-clock second by shifting into the next second.
if (targetDate.getTime() % 1000 != 0) {
return getTimeBefore(new Date(targetDate.getTime() + 999));
}
return getTimeBefore(targetDate);
}

Expand All @@ -1610,7 +1615,9 @@ private long findMinIncrement() {
} else if (hours.first() == ALL_SPEC_INT) {
return 3600000;
}
return 86400000;
// DST spring-forward days can be 23 hours, so using 24 hours here can skip
// a valid previous fire time around midnight transitions.
return 23L * 60L * 60L * 1000L;
}

private int minInSet(final TreeSet<Integer> set) {
Expand Down