!1324 完善季度相关 API

Merge pull request !1324 from zhouxy108/v5-dev

hutool-core/src/main/java/cn/hutool/core/date/Quarter.java

@@ -1,5 +1,11 @@
 package cn.hutool.core.date;
 
+import java.time.DateTimeException;
+import java.time.MonthDay;
+import java.time.temporal.ChronoField;
+
+import cn.hutool.core.lang.Assert;
+
 /**
  * 季度枚举
  *
@@ -25,8 +31,14 @@ public enum Quarter {
 	// ---------------------------------------------------------------
 	private final int value;
 
+	private final int firstMonth;
+	private final int lastMonth;
+
 	Quarter(int value) {
 		this.value = value;
+
+		this.lastMonth = value * 3;
+		this.firstMonth = lastMonth - 2;
 	}
 
 	public int getValue() {
@@ -58,4 +70,148 @@ public enum Quarter {
 				return null;
 		}
 	}
+
+	/**
+	 * 根据给定的月份值返回对应的季度
+	 *
+	 * @param monthValue 月份值，取值范围为1到12
+	 * @return 对应的季度
+	 * @throws IllegalArgumentException 如果月份值不在有效范围内（1到12），将抛出异常
+	 */
+	public static Quarter fromMonth(int monthValue) {
+		ChronoField.MONTH_OF_YEAR.checkValidValue(monthValue);
+		return of(computeQuarterValueInternal(monthValue));
+	}
+
+	/**
+	 * 根据给定的月份返回对应的季度
+	 *
+	 * @param month 月份
+	 * @return 对应的季度
+	 */
+	public static Quarter fromMonth(Month month) {
+		Assert.notNull(month);
+		final int monthValue = month.getValue();
+		return of(computeQuarterValueInternal(monthValue));
+	}
+
+	/**
+	 * 根据指定的年份，获取一个新的 YearQuarter 实例
+	 * 此方法允许在保持当前季度信息不变的情况下，更改年份
+	 *
+	 * @param year 指定的年份
+	 * @return 返回一个新的 YearQuarter 实例，年份更新为指定的年份
+	 */
+	public final YearQuarter atYear(int year) {
+		return YearQuarter.of(year, this);
+	}
+
+	// StaticFactoryMethods end
+
+	// computes
+
+	/**
+	 * 加上指定数量的季度
+	 *
+	 * @param quarters 所添加的季度数量
+	 * @return 计算结果
+	 */
+	public Quarter plus(long quarters) {
+		final int amount = (int) ((quarters % 4) + 4);
+		return Quarter.values()[(ordinal() + amount) % 4];
+	}
+
+	/**
+	 * 减去指定数量的季度
+	 * @param quarters 所减去的季度数量
+	 * @return 计算结果
+	 */
+	public Quarter minus(long quarters) {
+		return plus(-(quarters % 4));
+	}
+
+	// computes end
+
+	// Getters
+
+	/**
+	 * 该季度的第一个月
+	 *
+	 * @return 结果
+	 */
+	public Month firstMonth() {
+		return Month.of(firstMonthValue() - 1);
+	}
+
+	/**
+	 * 该季度的第一个月
+	 *
+	 * @return 结果。月份值从 1 开始，1 表示 1月，以此类推。
+	 */
+	public int firstMonthValue() {
+		return this.firstMonth;
+	}
+
+	/**
+	 * 该季度最后一个月
+	 *
+	 * @return 结果
+	 */
+	public Month lastMonth() {
+		return Month.of(lastMonthValue() - 1);
+	}
+
+	/**
+	 * 该季度最后一个月
+	 *
+	 * @return 结果。1 表示 1月，以此类推。
+	 */
+	public int lastMonthValue() {
+		return this.lastMonth;
+	}
+
+	/**
+	 * 该季度的第一天
+	 *
+	 * @return 结果
+	 */
+	public MonthDay firstMonthDay() {
+		return MonthDay.of(firstMonthValue(), 1);
+	}
+
+	/**
+	 * 该季度的最后一天
+	 *
+	 * @return 结果
+	 */
+	public MonthDay lastMonthDay() {
+		// 季度的最后一个月不可能是 2 月，不考虑闰年
+		final Month month = lastMonth();
+		return MonthDay.of(month.toJdkMonth(), month.getLastDay(false));
+	}
+
+	// Getters end
+
+	/**
+	 * 检查季度的值。（1~4）
+	 * @param value 季度值
+	 * @return 在取值范围内的值
+	 */
+	public static int checkValidIntValue(int value) {
+		Assert.isTrue(value >= 1 && value <= 4,
+				() -> new DateTimeException("Invalid value for Quarter: " + value));
+		return value;
+	}
+
+	// Internal
+
+	/**
+	 * 计算给定月份对应的季度值
+	 *
+	 * @param monthValue 月份值，取值范围为1到12
+	 * @return 对应的季度值
+	 */
+	private static int computeQuarterValueInternal(int monthValue) {
+		return (monthValue - 1) / 3 + 1;
+	}
 }

hutool-core/src/main/java/cn/hutool/core/date/YearQuarter.java

@@ -0,0 +1,365 @@
+package cn.hutool.core.date;
+
+import static java.time.temporal.ChronoField.YEAR;
+
+import java.io.Serializable;
+import java.time.LocalDate;
+import java.time.YearMonth;
+import java.time.temporal.ChronoField;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Objects;
+
+/**
+ * 表示年份与季度
+ *
+ * @author ZhouXY
+ */
+public final class YearQuarter implements Comparable<YearQuarter>, Serializable {
+	private static final long serialVersionUID = 3804145964419489753L;
+
+	/** 年份 */
+	private final int year;
+	/** 季度 */
+	private final Quarter quarter;
+	/** 季度开始日期 */
+	private final LocalDate firstDate;
+	/** 季度结束日期 */
+	private final LocalDate lastDate;
+
+	private YearQuarter(int year, Quarter quarter) {
+		this.year = year;
+		this.quarter = quarter;
+		this.firstDate = quarter.firstMonthDay().atYear(year);
+		this.lastDate = quarter.lastMonthDay().atYear(year);
+	}
+
+	// #region - StaticFactory
+
+	/**
+	 * 根据指定年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param year 年份
+	 * @param quarter 季度
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(int year, int quarter) {
+		int yearValue = YEAR.checkValidIntValue(year);
+		int quarterValue = Quarter.checkValidIntValue(quarter);
+		return new YearQuarter(yearValue, Quarter.of(quarterValue));
+	}
+
+	/**
+	 * 根据指定年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param year 年份
+	 * @param quarter 季度
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(int year, Quarter quarter) {
+		return new YearQuarter(YEAR.checkValidIntValue(year), Objects.requireNonNull(quarter));
+	}
+
+	/**
+	 * 根据指定日期，判断日期所在的年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param date 日期
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(LocalDate date) {
+		Objects.requireNonNull(date);
+		return new YearQuarter(date.getYear(), Quarter.fromMonth(date.getMonthValue()));
+	}
+
+	/**
+	 * 根据指定日期，判断日期所在的年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param date 日期
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(Date date) {
+		Objects.requireNonNull(date);
+		@SuppressWarnings("deprecation")
+		final int yearValue = YEAR.checkValidIntValue(date.getYear() + 1900L);
+		@SuppressWarnings("deprecation")
+		final int monthValue = date.getMonth() + 1;
+		return new YearQuarter(yearValue, Quarter.fromMonth(monthValue));
+	}
+
+	/**
+	 * 根据指定日期，判断日期所在的年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param date 日期
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(Calendar date) {
+		Objects.requireNonNull(date);
+		final int yearValue = ChronoField.YEAR.checkValidIntValue(date.get(Calendar.YEAR));
+		final int monthValue = date.get(Calendar.MONTH) + 1;
+		return new YearQuarter(yearValue, Quarter.fromMonth(monthValue));
+	}
+
+	/**
+	 * 根据指定年月，判断其所在的年份与季度，创建 {@link YearQuarter} 实例
+	 *
+	 * @param yearMonth 年月
+	 * @return {@link YearQuarter} 实例
+	 */
+	public static YearQuarter of(YearMonth yearMonth) {
+		Objects.requireNonNull(yearMonth);
+		return of(yearMonth.getYear(), Quarter.fromMonth(yearMonth.getMonthValue()));
+	}
+
+	/**
+	 * 当前年季
+	 *
+	 * @return 当前年季
+	 */
+
+	public static YearQuarter now() {
+		return of(LocalDate.now());
+	}
+
+	// #endregion
+
+	// #region - Getters
+
+	/**
+	 * 年份
+	 * @return 年份
+	 */
+	public int getYear() {
+		return this.year;
+	}
+
+	/**
+	 * 季度
+	 * @return 季度
+	 */
+	public Quarter getQuarter() {
+		return this.quarter;
+	}
+
+	/**
+	 * 季度值。从 1 开始。
+	 * @return 季度值
+	 */
+	public int getQuarterValue() {
+		return this.quarter.getValue();
+	}
+
+	/**
+	 * 该季度第一个月
+	 * @return {@link YearMonth} 对象
+	 */
+	public YearMonth firstYearMonth() {
+		return YearMonth.of(this.year, this.quarter.firstMonthValue());
+	}
+
+	/**
+	 * 该季度第一个月
+	 * @return {@link Month} 对象
+	 */
+	public Month firstMonth() {
+		return this.quarter.firstMonth();
+	}
+
+	/**
+	 * 该季度的第一个月
+	 * @return 结果。月份值从 1 开始，1 表示 1月，以此类推。
+	 */
+	public int firstMonthValue() {
+		return this.quarter.firstMonthValue();
+	}
+
+	/**
+	 * 该季度的最后一个月
+	 * @return {@link YearMonth} 对象
+	 */
+	public YearMonth lastYearMonth() {
+		return YearMonth.of(this.year, this.quarter.lastMonthValue());
+	}
+
+	/**
+	 * 该季度的最后一个月
+	 * @return {@link Month} 对象
+	 */
+	public Month lastMonth() {
+		return this.quarter.lastMonth();
+	}
+
+	/**
+	 * 该季度的最后一个月
+	 * @return 结果。月份值从 1 开始，1 表示 1月，以此类推。
+	 */
+	public int lastMonthValue() {
+		return this.quarter.lastMonthValue();
+	}
+
+	/**
+	 * 该季度的第一天
+	 * @return {@link LocalDate} 对象
+	 */
+	public LocalDate firstDate() {
+		return firstDate;
+	}
+
+	/**
+	 * 该季度的最后一天
+	 * @return {@link LocalDate} 对象
+	 */
+	public LocalDate lastDate() {
+		return lastDate;
+	}
+
+	// #endregion
+
+	// #region - computes
+
+	/**
+	 * 添加季度
+	 * @param quartersToAdd 要添加的季度数
+	 * @return 计算结果
+	 */
+	public YearQuarter plusQuarters(long quartersToAdd) {
+		if (quartersToAdd == 0L) {
+			return this;
+		}
+		long quarterCount = this.year * 4L + (this.quarter.getValue() - 1);
+		long calcQuarters = quarterCount + quartersToAdd; // safe overflow
+		int newYear = YEAR.checkValidIntValue(Math.floorDiv(calcQuarters, 4));
+		int newQuarter = (int) Math.floorMod(calcQuarters, 4) + 1;
+		return new YearQuarter(newYear, Quarter.of(newQuarter));
+	}
+
+	/**
+	 * 减去季度
+	 * @param quartersToMinus 要减去的季度数
+	 * @return 计算结果
+	 */
+	public YearQuarter minusQuarters(long quartersToMinus) {
+		return plusQuarters(-quartersToMinus);
+	}
+
+	/**
+	 * 下一个季度
+	 * @return 结果
+	 */
+	public YearQuarter nextQuarter() {
+		return plusQuarters(1L);
+	}
+
+	/**
+	 * 上一个季度
+	 * @return 结果
+	 */
+	public YearQuarter lastQuarter() {
+		return minusQuarters(1L);
+	}
+
+	/**
+	 * 添加年份
+	 * @param yearsToAdd 要添加的年份数
+	 * @return 计算结果
+	 */
+	public YearQuarter plusYears(long yearsToAdd) {
+		if (yearsToAdd == 0L) {
+			return this;
+		}
+		int newYear = YEAR.checkValidIntValue(this.year + yearsToAdd); // safe overflow
+		return new YearQuarter(newYear, this.quarter);
+	}
+
+	/**
+	 * 减去年份
+	 * @param yearsToMinus 要减去的年份数
+	 * @return 计算结果
+	 */
+	public YearQuarter minusYears(long yearsToMinus) {
+		return plusYears(-yearsToMinus);
+	}
+
+	/**
+	 * 下一年同季度
+	 * @return 计算结果
+	 */
+	public YearQuarter nextYear() {
+		return plusYears(1L);
+	}
+
+	/**
+	 * 上一年同季度
+	 * @return 计算结果
+	 */
+	public YearQuarter lastYear() {
+		return minusYears(1L);
+	}
+
+	// #endregion
+
+	// #region - hashCode & equals
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(year, quarter);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		YearQuarter other = (YearQuarter) obj;
+		return year == other.year && quarter == other.quarter;
+	}
+
+	// #endregion
+
+	// #region - compare
+
+	@Override
+	public int compareTo(YearQuarter other) {
+		int cmp = (this.year - other.year);
+		if (cmp == 0) {
+			cmp = this.quarter.compareTo(other.quarter);
+		}
+		return cmp;
+	}
+
+	/**
+	 * 判断是否在指定年份季度之前
+	 * @param other 比较对象
+	 * @return 结果
+	 */
+	public boolean isBefore(YearQuarter other) {
+		return this.compareTo(other) < 0;
+	}
+
+	/**
+	 * 判断是否在指定年份季度之后
+	 * @param other 比较对象
+	 * @return 结果
+	 */
+	public boolean isAfter(YearQuarter other) {
+		return this.compareTo(other) > 0;
+	}
+
+	// #endregion
+
+	// #region - toString
+
+	/**
+	 * 返回 {@link YearQuarter} 的字符串表示形式，如 "2024 Q3"
+	 *
+	 * @return {@link YearQuarter} 的字符串表示形式
+	 */
+	@Override
+	public String toString() {
+		return this.year + " " + this.quarter.name();
+	}
+
+	// #endregion
+}

hutool-core/src/test/java/cn/hutool/core/date/QuarterTest.java

@@ -0,0 +1,268 @@
+package cn.hutool.core.date;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.time.MonthDay;
+
+import org.junit.jupiter.api.Test;
+
+public class QuarterTest {
+
+	@Test
+	void testQ1() {
+		Quarter quarter = Quarter.of(1);
+		assertSame(Quarter.Q1, quarter);
+		assertSame(quarter, Quarter.valueOf("Q1"));
+		assertEquals(1, quarter.getValue());
+		assertEquals("Q1", quarter.name());
+
+		assertNull(Quarter.of(0));
+
+		// ==========
+
+		int firstMonthValue = quarter.firstMonthValue();
+		assertEquals(1, firstMonthValue);
+
+		Month firstMonth = quarter.firstMonth();
+		assertEquals(Month.JANUARY, firstMonth);
+
+		// ==========
+
+		int lastMonthValue = quarter.lastMonthValue();
+		assertEquals(3, lastMonthValue);
+
+		Month lastMonth = quarter.lastMonth();
+		assertEquals(Month.MARCH, lastMonth);
+
+		// ==========
+
+		MonthDay firstMonthDay = quarter.firstMonthDay();
+		assertEquals(firstMonthDay, MonthDay.of(1, 1));
+
+		MonthDay lastMonthDay = quarter.lastMonthDay();
+		assertEquals(lastMonthDay, MonthDay.of(3, 31));
+	}
+
+	@Test
+	void testQ2() {
+		Quarter quarter = Quarter.of(2);
+		assertSame(Quarter.Q2, quarter);
+		assertSame(quarter, Quarter.valueOf("Q2"));
+		assertEquals(2, quarter.getValue());
+		assertEquals("Q2", quarter.name());
+
+		assertNull(Quarter.of(5));
+
+		// ==========
+
+		int firstMonthValue = quarter.firstMonthValue();
+		assertEquals(4, firstMonthValue);
+
+		Month firstMonth = quarter.firstMonth();
+		assertEquals(Month.APRIL, firstMonth);
+
+		// ==========
+
+		int lastMonthValue = quarter.lastMonthValue();
+		assertEquals(6, lastMonthValue);
+
+		Month lastMonth = quarter.lastMonth();
+		assertEquals(Month.JUNE, lastMonth);
+
+		// ==========
+
+		MonthDay firstMonthDay = quarter.firstMonthDay();
+		assertEquals(firstMonthDay, MonthDay.of(4, 1));
+
+		MonthDay lastMonthDay = quarter.lastMonthDay();
+		assertEquals(lastMonthDay, MonthDay.of(6, 30));
+	}
+
+	@Test
+	void testQ3() {
+		Quarter quarter = Quarter.of(3);
+		assertSame(Quarter.Q3, quarter);
+		assertSame(quarter, Quarter.valueOf("Q3"));
+		assertEquals(3, quarter.getValue());
+		assertEquals("Q3", quarter.name());
+
+		assertThrows(IllegalArgumentException.class, () -> {
+			Quarter.valueOf("Abc");
+		});
+
+		// ==========
+
+		int firstMonthValue = quarter.firstMonthValue();
+		assertEquals(7, firstMonthValue);
+
+		Month firstMonth = quarter.firstMonth();
+		assertEquals(Month.JULY, firstMonth);
+
+		// ==========
+
+		int lastMonthValue = quarter.lastMonthValue();
+		assertEquals(9, lastMonthValue);
+
+		Month lastMonth = quarter.lastMonth();
+		assertEquals(Month.SEPTEMBER, lastMonth);
+
+		// ==========
+
+		MonthDay firstMonthDay = quarter.firstMonthDay();
+		assertEquals(firstMonthDay, MonthDay.of(7, 1));
+
+		MonthDay lastMonthDay = quarter.lastMonthDay();
+		assertEquals(lastMonthDay, MonthDay.of(9, 30));
+	}
+
+	@Test
+	void testQ4() {
+		Quarter quarter = Quarter.of(4);
+		assertSame(Quarter.Q4, quarter);
+		assertSame(quarter, Quarter.valueOf("Q4"));
+		assertEquals(4, quarter.getValue());
+		assertEquals("Q4", quarter.name());
+
+		assertThrows(IllegalArgumentException.class, () -> {
+			Quarter.valueOf("Q5");
+		});
+
+		// ==========
+
+		int firstMonthValue = quarter.firstMonthValue();
+		assertEquals(10, firstMonthValue);
+
+		Month firstMonth = quarter.firstMonth();
+		assertEquals(Month.OCTOBER, firstMonth);
+
+		// ==========
+
+		int lastMonthValue = quarter.lastMonthValue();
+		assertEquals(12, lastMonthValue);
+		Month lastMonth = quarter.lastMonth();
+		assertEquals(Month.DECEMBER, lastMonth);
+
+		// ==========
+
+		MonthDay firstMonthDay = quarter.firstMonthDay();
+		assertEquals(firstMonthDay, MonthDay.of(10, 1));
+
+		MonthDay lastMonthDay = quarter.lastMonthDay();
+		assertEquals(lastMonthDay, MonthDay.of(12, 31));
+	}
+
+	@Test
+	void testPlusZeroAndPositiveRealNumbers() {
+		for (int i = 0; i < 100; i += 4) {
+			assertEquals(Quarter.Q1, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q4.plus(i));
+		}
+		for (int i = 1; i < 100 + 1; i += 4) {
+			assertEquals(Quarter.Q2, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q4.plus(i));
+		}
+		for (int i = 2; i < 100 + 2; i += 4) {
+			assertEquals(Quarter.Q3, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q4.plus(i));
+		}
+		for (int i = 3; i < 100 + 3; i += 4) {
+			assertEquals(Quarter.Q4, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q4.plus(i));
+		}
+	}
+
+	@Test
+	void testPlusZeroAndNegativeNumber() {
+		for (int i = 0; i > -100; i -= 4) {
+			assertEquals(Quarter.Q1, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q4.plus(i));
+		}
+		for (int i = -1; i > -(100 + 1); i -= 4) {
+			assertEquals(Quarter.Q4, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q4.plus(i));
+		}
+		for (int i = -2; i > -(100 + 2); i -= 4) {
+			assertEquals(Quarter.Q3, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q2, Quarter.Q4.plus(i));
+		}
+		for (int i = -3; i > -(100 + 3); i -= 4) {
+			assertEquals(Quarter.Q2, Quarter.Q1.plus(i));
+			assertEquals(Quarter.Q3, Quarter.Q2.plus(i));
+			assertEquals(Quarter.Q4, Quarter.Q3.plus(i));
+			assertEquals(Quarter.Q1, Quarter.Q4.plus(i));
+		}
+	}
+
+	@Test
+	void testMinusZeroAndNegativeNumber() {
+		for (int i = 0; i < 100; i += 4) {
+			assertEquals(Quarter.Q1, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q4.minus(i));
+		}
+		for (int i = 1; i < 100 + 1; i += 4) {
+			assertEquals(Quarter.Q4, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q4.minus(i));
+		}
+		for (int i = 2; i < 100 + 2; i += 4) {
+			assertEquals(Quarter.Q3, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q4.minus(i));
+		}
+		for (int i = 3; i < 100 + 3; i += 4) {
+			assertEquals(Quarter.Q2, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q4.minus(i));
+		}
+	}
+
+	@Test
+	void testMinusZeroAndPositiveRealNumbers() {
+		for (int i = 0; i > -100; i -= 4) {
+			assertEquals(Quarter.Q1, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q4.minus(i));
+		}
+		for (int i = -1; i > -(100 + 1); i -= 4) {
+			assertEquals(Quarter.Q2, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q4.minus(i));
+		}
+		for (int i = -2; i > -(100 + 2); i -= 4) {
+			assertEquals(Quarter.Q3, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q4, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q4.minus(i));
+		}
+		for (int i = -3; i > -(100 + 3); i -= 4) {
+			assertEquals(Quarter.Q4, Quarter.Q1.minus(i));
+			assertEquals(Quarter.Q1, Quarter.Q2.minus(i));
+			assertEquals(Quarter.Q2, Quarter.Q3.minus(i));
+			assertEquals(Quarter.Q3, Quarter.Q4.minus(i));
+		}
+	}
+}

pom.xml

@@ -57,6 +57,12 @@
 			<version>${junit.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-params</artifactId>
+			<version>${junit.version}</version>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.projectlombok</groupId>
 			<artifactId>lombok</artifactId>