测试(VS自带框架):

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;/// <summary>
///This is a test class for YearMonthTest and is intended
///to contain all YearMonthTest Unit Tests
///</summary>
[TestClass()]
public class YearMonthTest
{/// <summary>///A test for YearMonth Constructor///</summary>[TestMethod()]public void YearMonthConstructorTest(){var date = new DateTime(2000, 1, 1);var target = new YearMonth(date);Assert.AreEqual(2000, target.Year);Assert.AreEqual(1, target.Month);}/// <summary>///A test for YearMonth Constructor///</summary>[TestMethod()]public void YearMonthConstructorTest1(){YearMonth target = new YearMonth(2010, 4);Assert.AreEqual(2010, target.Year);Assert.AreEqual(4, target.Month);}/// <summary>///A test for GetDate///</summary>[TestMethod()]public void GetDateTest(){var target = new YearMonth(2010, 5);var expected = new DateTime(2010, 5, 3);var actual = target.GetDate(3);Assert.AreEqual(expected, actual);}[TestMethod]public void GetDateThrows(){Assert.IsTrue(Throws(typeof(ArgumentOutOfRangeException), () => new YearMonth(2012, 12).GetDate(32)));}/// <summary>///A test for ToString///</summary>[TestMethod()]public void ToStringTest(){var target = new YearMonth(2008, 3);Assert.AreEqual("200803", target.ToString());}/// <summary>///A test for IsValid///</summary>[TestMethod()]public void IsValidTest(){Assert.IsTrue(new YearMonth(2008, 12).IsValid);Assert.IsFalse(new YearMonth(2010, 13).IsValid);Assert.IsFalse(new YearMonth(2010, 0).IsValid);Assert.IsFalse(new YearMonth(2010, -3).IsValid);Assert.IsFalse(new YearMonth(0, 3).IsValid);Assert.IsFalse(new YearMonth(-2, 3).IsValid);Assert.IsTrue(new YearMonth(9999, 12).IsValid);Assert.IsFalse(new YearMonth(10000, 1).IsValid);Assert.IsFalse(new YearMonth(-2, -3).IsValid);}/// <summary>///A test for Equals///</summary>[TestMethod()]public void EqualsTest(){var target = new YearMonth(2010, 4);Assert.IsTrue(target.Equals(new YearMonth(2010, 4)));Assert.IsFalse(target.Equals(new YearMonth(2010, 3)));Assert.IsFalse(target.Equals(string.Empty));}/// <summary>///A test for TryParse///</summary>[TestMethod()]public void TryParseTest(){YearMonth result;var success = YearMonth.TryParse("201012", out result);Assert.IsTrue(success);Assert.AreEqual(new YearMonth(2010, 12), result);success = YearMonth.TryParse("", out result);Assert.IsFalse(success);Assert.AreEqual(result, null);}/// <summary>///A test for Parse///</summary>[TestMethod()]public void ParseTest(){Assert.AreEqual(new YearMonth(2008, 12), YearMonth.Parse("200812"));}[TestMethod]public void ParseThrows(){Assert.IsTrue(Throws(typeof(ArgumentNullException), () => YearMonth.Parse(null)));Assert.IsTrue(Throws(typeof(ArgumentException), () => YearMonth.Parse("")));Assert.IsTrue(Throws(typeof(ArgumentException), () => YearMonth.Parse("aaaaaa")));Assert.IsTrue(Throws(typeof(ArgumentException), () => YearMonth.Parse("20121221")));}/// <summary>///A test for AddYears///</summary>[TestMethod()]public void AddYearsTest(){Assert.AreEqual(new YearMonth(2011, 11), new YearMonth(2008, 11).AddYears(3));Assert.AreEqual(new YearMonth(2011, 11), new YearMonth(2011, 11).AddYears(0));Assert.AreEqual(new YearMonth(2011, 11), new YearMonth(2012, 11).AddYears(-1));}/// <summary>///A test for AddMonths///</summary>[TestMethod()]public void AddMonthsTest(){Assert.AreEqual(new YearMonth(2010, 4), new YearMonth(2010, 3).AddMonths(1));Assert.AreEqual(new YearMonth(2010, 4), new YearMonth(2010, 4).AddMonths(0));Assert.AreEqual(new YearMonth(2010, 4), new YearMonth(2010, 8).AddMonths(-4));Assert.AreEqual(new YearMonth(2010, 1), new YearMonth(2009, 11).AddMonths(2));Assert.AreEqual(new YearMonth(2009, 11), new YearMonth(2010, 1).AddMonths(-2));Assert.AreEqual(new YearMonth(2009, 12), new YearMonth(2010, 1).AddMonths(-1));Assert.AreEqual(new YearMonth(2010, 1), new YearMonth(2009, 12).AddMonths(1));}static bool Throws(Type exceptionType, Action action){try{action();}catch (Exception ex){if (ex.GetType() == exceptionType || ex.GetType().IsSubclassOf(exceptionType))return true;throw;}return false;}
}

代码:

using System;
using System.Linq;/// <summary>
/// 代表一个年份中的某个指定月份. 如:2008年10月.
/// </summary>
public sealed class YearMonth
{private readonly int _year;private readonly int _month;/// <summary>/// 用指定的年份和月份构造一个 YearMonth 对象./// </summary>/// <param name="year">年号,如2012.</param>/// <param name="month">月份,1代表1月,12代表12月.</param>public YearMonth(int year, int month){_year = year;_month = month;}/// <summary>/// 根据指定日期所在的月份构造一个 YearMonth 对象./// </summary>/// <param name="date">指定的日期.它的年份和月份部分会作为构造的YearMonth的值使用.</param>public YearMonth(DateTime date){_year = date.Year;_month = date.Month;}public int Year{get { return _year; }}public int Month{get { return _month; }}/// <summary>/// 是否是有效的值.无效的值可能是年份小于1, 或年份大于9999, 或月份小于1, 或月份大于12./// </summary>public bool IsValid{get{return 0 < Year && Year < 10000&& 0 < Month && Month < 13;}}/// <summary>/// 获取代表该月指定日期的 DateTime 对象/// </summary>/// <param name="day">日期,范围1到31.</param>/// <exception cref="ArgumentOutOfRangeException">day大于本月的天数.</exception>public DateTime GetDate(int day){return new DateTime(Year, Month, day);}/// <summary>/// 返回一个新YearMonth对象,其值为当前对象的值加上指定个年份/// </summary>/// <param name="value">要在当前年月上增加多少年</param>public YearMonth AddYears(int value){return new YearMonth(Year + value, Month);}/// <summary>/// 返回一个新YearMonth对象,其值为当前对象的值加上指定个月份/// </summary>/// <param name="value">要在当前年月上增加多少个月</param>public YearMonth AddMonths(int value){var totalMonths = Year * 12 + Month + value;var year = totalMonths / 12;var month = totalMonths % 12;if (month == 0){month = 12;year--;}return new YearMonth(year, month);}/// <summary>/// 返回数字代表的年月份值,共6位数字,前4位代表年份,后两位代表月份,如:200805/// </summary>public override string ToString(){return "{0:D4}{1:D2}".FormatWith(Year, Month);}/// <summary>/// 判断一个是否与当前对象代表相同的值的YearMonth对象./// </summary>public override bool Equals(object obj){return Equals(obj as YearMonth);}/// <summary>///判断另一个YearMonth对象是否与当前对象代表相同的值. /// </summary>public bool Equals(YearMonth rhs){if (ReferenceEquals(null, rhs))return false;if (ReferenceEquals(this, rhs))return true;return _year == rhs._year &&_month == rhs._month;}public override int GetHashCode(){unchecked{return (_year * 397) ^ _month;}}public static bool operator ==(YearMonth lhs, YearMonth rhs){return Object.Equals(lhs, rhs);}public static bool operator !=(YearMonth lhs, YearMonth rhs){return !(lhs == rhs);}public static bool TryParse(string s, out YearMonth result){try{result = Parse(s);return true;}catch (ArgumentException){result = null;return false;}}/// <summary>/// 通过解析字符串构造一个YearMonth对象./// </summary>/// <param name="s">要解析的字符串.</param>/// <exception cref="ArgumentNullException">s为null.</exception>/// <exception cref="ArgumentException">s包含非数字字符,或s的长度不为6.</exception>public static YearMonth Parse(string s){if (s == null)throw new ArgumentNullException("s");if (s.Length != 6 || s.Any(x => x < '0' || x > '9'))throw new ArgumentException("s应该是6位数字.");var year = int.Parse(s.Substring(0, 4));var month = int.Parse(s.Substring(4));return new YearMonth(year, month);}
}

辅助方法:

public static class StringExtensions
{public static string FormatWith(this string format, object arg0){return string.Format(format, arg0);}public static string FormatWith(this string format, object arg0, object arg1){return string.Format(format, arg0, arg1);}public static string FormatWith(this string format, object arg0, object arg1, object arg2){return string.Format(format, arg0, arg1, arg2);}
}