Expose and add unit tests for ISOWeek (#30386)

* Expose ISOWeek in System.Globalization

* Add unit tests for ISOWeek

* PR Feedback

* Add ISOWeek to ApiCompatBaseline

* Added more edge-case tests

src/System.Globalization.Calendars/tests/Configurations.props

@@ -1,8 +1,9 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <BuildConfigurations>
       netstandard;
+      netcoreapp;
     </BuildConfigurations>
   </PropertyGroup>
 </Project>

src/System.Globalization.Calendars/tests/ISOWeek/ISOWeekTests.netcoreapp.cs

@@ -0,0 +1,207 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace System.Globalization
+{
+    public static class ISOWeekTests
+    {
+        // The following 71 years in a 400-year cycle have 53 weeks (371 days).
+        // Years not listed have 52 weeks (364 days). Add 2000 for current years.
+        private static readonly HashSet<int> s_yearsWith53Weeks = new HashSet<int>
+        {
+            004, 009, 015, 020, 026,
+            032, 037, 043, 048, 054,
+            060, 065, 071, 076, 082,
+            088, 093, 099, 105, 111, 116, 122,
+            128, 133, 139, 144, 150,
+            156, 161, 167, 172, 178,
+            184, 189, 195, 201, 207, 212, 218,
+            224, 229, 235, 240, 246,
+            252, 257, 263, 268, 274,
+            280, 285, 291, 296, 303, 308, 314,
+            320, 325, 331, 336, 342,
+            348, 353, 359, 364, 370,
+            376, 381, 387, 392, 398
+        };
+
+        // From https://en.wikipedia.org/wiki/ISO_week_date#Relation_with_the_Gregorian_calendar.
+        private static readonly DateData[] s_dateData =
+        {
+            new DateData(new DateTime(0001, 01, 01), 0001, 01, DayOfWeek.Monday),
+            new DateData(new DateTime(2005, 01, 01), 2004, 53, DayOfWeek.Saturday),
+            new DateData(new DateTime(2005, 01, 02), 2004, 53, DayOfWeek.Sunday),
+            new DateData(new DateTime(2005, 12, 31), 2005, 52, DayOfWeek.Saturday),
+            new DateData(new DateTime(2006, 01, 01), 2005, 52, DayOfWeek.Sunday),
+            new DateData(new DateTime(2006, 01, 02), 2006, 01, DayOfWeek.Monday),
+            new DateData(new DateTime(2006, 12, 31), 2006, 52, DayOfWeek.Sunday),
+            new DateData(new DateTime(2007, 01, 01), 2007, 01, DayOfWeek.Monday),
+            new DateData(new DateTime(2007, 12, 30), 2007, 52, DayOfWeek.Sunday),
+            new DateData(new DateTime(2007, 12, 31), 2008, 01, DayOfWeek.Monday),
+            new DateData(new DateTime(2008, 01, 01), 2008, 01, DayOfWeek.Tuesday),
+            new DateData(new DateTime(2008, 12, 28), 2008, 52, DayOfWeek.Sunday),
+            new DateData(new DateTime(2008, 12, 29), 2009, 01, DayOfWeek.Monday),
+            new DateData(new DateTime(2008, 12, 30), 2009, 01, DayOfWeek.Tuesday),
+            new DateData(new DateTime(2008, 12, 31), 2009, 01, DayOfWeek.Wednesday),
+            new DateData(new DateTime(2009, 01, 01), 2009, 01, DayOfWeek.Thursday),
+            new DateData(new DateTime(2009, 12, 31), 2009, 53, DayOfWeek.Thursday),
+            new DateData(new DateTime(2010, 01, 01), 2009, 53, DayOfWeek.Friday),
+            new DateData(new DateTime(2010, 01, 02), 2009, 53, DayOfWeek.Saturday),
+            new DateData(new DateTime(2010, 01, 03), 2009, 53, DayOfWeek.Sunday),
+            new DateData(new DateTime(9999, 12, 31), 9999, 52, DayOfWeek.Friday),
+        };
+
+        private static readonly YearData[] s_yearData =
+        {
+            new YearData(0001, new DateTime(0001, 01, 01), new DateTime(0001, 12, 30)),
+            new YearData(2005, new DateTime(2005, 01, 03), new DateTime(2006, 01, 01)),
+            new YearData(2006, new DateTime(2006, 01, 02), new DateTime(2006, 12, 31)),
+            new YearData(2007, new DateTime(2007, 01, 01), new DateTime(2007, 12, 30)),
+            new YearData(2008, new DateTime(2007, 12, 31), new DateTime(2008, 12, 28)),
+            new YearData(2009, new DateTime(2008, 12, 29), new DateTime(2010, 01, 03)),
+            new YearData(9998, new DateTime(9997, 12, 29), new DateTime(9999, 01, 03)),
+        };
+
+        public static IEnumerable<object[]> GetWeekOfYear_TestData()
+        {
+            return s_dateData.Select(x => new object[] {x.Date, x.Week});
+        }
+
+        public static IEnumerable<object[]> GetYear_TestData()
+        {
+            return s_dateData.Select(x => new object[] {x.Date, x.Year});
+        }
+
+        public static IEnumerable<object[]> ToDateTime_TestData()
+        {
+            return s_dateData.Select(x => new object[] {x.Year, x.Week, x.DayOfWeek, x.Date});
+        }
+
+        public static IEnumerable<object[]> GetYearStart_TestData()
+        {
+            return s_yearData.Select(x => new object[] {x.Year, x.StartDate});
+        }
+
+        public static IEnumerable<object[]> GetYearEnd_TestData()
+        {
+            return s_yearData.Select(x => new object[] {x.Year, x.EndDate});
+        }
+
+        [Theory, MemberData(nameof(GetWeekOfYear_TestData))]
+        public static void GetWeekOfYear(DateTime date, int expected)
+        {
+            Assert.Equal(expected, ISOWeek.GetWeekOfYear(date));
+        }
+
+        [Theory, MemberData(nameof(GetYear_TestData))]
+        public static void GetYear(DateTime date, int expected)
+        {
+            Assert.Equal(expected, ISOWeek.GetYear(date));
+        }
+
+        [Theory, MemberData(nameof(ToDateTime_TestData))]
+        public static void ToDateTime(int year, int week, DayOfWeek dayOfWeek, DateTime expected)
+        {
+            Assert.Equal(expected, ISOWeek.ToDateTime(year, week, dayOfWeek));
+        }
+
+        [Theory]
+        [InlineData(0)]
+        [InlineData(10000)]
+        public static void ToDateTime_WithInvalidYear_Throws(int year)
+        {
+            AssertExtensions.Throws<ArgumentOutOfRangeException>(nameof(year), () => ISOWeek.ToDateTime(year, 1, DayOfWeek.Friday));
+        }
+
+        [Theory]
+        [InlineData(0)]
+        [InlineData(54)]
+        public static void ToDateTime_WithInvalidWeek_Throws(int week)
+        {
+            AssertExtensions.Throws<ArgumentOutOfRangeException>(nameof(week), () => ISOWeek.ToDateTime(2018, week, DayOfWeek.Friday));
+        }
+
+        [Theory]
+        [InlineData(-1)]
+        [InlineData(8)]
+        public static void ToDateTime_WithInvalidDayOfWeek_Throws(int dayOfWeek)
+        {
+            AssertExtensions.Throws<ArgumentOutOfRangeException>(nameof(dayOfWeek), () => ISOWeek.ToDateTime(2018, 1, (DayOfWeek)dayOfWeek));
+        }
+
+        [Fact]
+        public static void GetWeeksInYear()
+        {
+            for (int year = 0; year <= 400; year++)
+            {
+                int expected = s_yearsWith53Weeks.Contains(year) ? 53 : 52;
+                Assert.Equal(expected, ISOWeek.GetWeeksInYear(2000 + year));
+            }
+        }
+
+        [Theory]
+        [InlineData(0)]
+        [InlineData(10000)]
+        public static void GetWeeksInYear_WithInvalidYear_Throws(int year)
+        {
+            AssertExtensions.Throws<ArgumentOutOfRangeException>(nameof(year), () => ISOWeek.GetWeeksInYear(year));
+        }
+
+        [Theory, MemberData(nameof(GetYearStart_TestData))]
+        public static void GetYearStart(int year, DateTime expected)
+        {
+            Assert.Equal(expected, ISOWeek.GetYearStart(year));
+        }
+
+        [Theory, MemberData(nameof(GetYearEnd_TestData))]
+        public static void GetYearEnd(int year, DateTime expected)
+        {
+            Assert.Equal(expected, ISOWeek.GetYearEnd(year));
+        }
+
+        [Fact]
+        public static void GetYearEnd_ForYear9999_Throws()
+        {
+            AssertExtensions.Throws<ArgumentOutOfRangeException>("value", () => ISOWeek.GetYearEnd(9999));
+        }
+
+        private struct DateData
+        {
+            public readonly DateTime Date;
+
+            public readonly int Year;
+
+            public readonly int Week;
+
+            public readonly DayOfWeek DayOfWeek;
+
+            public DateData(DateTime date, int year, int week, DayOfWeek dayOfWeek)
+            {
+                Date = date;
+                Year = year;
+                Week = week;
+                DayOfWeek = dayOfWeek;
+            }
+        }
+
+        private struct YearData
+        {
+            public readonly int Year;
+
+            public readonly DateTime StartDate;
+
+            public readonly DateTime EndDate;
+
+            public YearData(int year, DateTime startDate, DateTime endDate)
+            {
+                Year = year;
+                StartDate = startDate;
+                EndDate = endDate;
+            }
+        }
+    }
+}

src/System.Globalization.Calendars/tests/System.Globalization.Calendars.Tests.csproj

@@ -6,6 +6,8 @@
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard-Release|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Debug|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Release|AnyCPU'" />
   <ItemGroup>
     <Compile Include="CalendarHelpers.cs" />
     <Compile Include="GregorianCalendar\GregorianCalendarCtor.cs" />
@@ -109,8 +111,11 @@
     <Compile Include="$(CommonTestPath)\System\RandomDataGenerator.cs" />
     <!-- Helpers -->
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetGroup)' == 'netcoreapp'">
+    <Compile Include="ISOWeek\ISOWeekTests.netcoreapp.cs" />
+  </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="Resources\$(AssemblyName).rd.xml" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
-</Project>
+</Project>

src/System.Runtime/ref/System.Runtime.cs

@@ -4530,6 +4530,15 @@ namespace System.Globalization
         public string GetUnicode(string ascii, int index) { throw null; }
         public string GetUnicode(string ascii, int index, int count) { throw null; }
     }
+    public static partial class ISOWeek
+    {
+        public static int GetWeekOfYear(System.DateTime date) { throw null; }
+        public static int GetWeeksInYear(int year) { throw null; }
+        public static int GetYear(System.DateTime date) { throw null; }
+        public static System.DateTime GetYearEnd(int year) { throw null; }
+        public static System.DateTime GetYearStart(int year) { throw null; }
+        public static System.DateTime ToDateTime(int year, int week, System.DayOfWeek dayOfWeek) { throw null; }
+    }
     public partial class JapaneseCalendar : System.Globalization.Calendar
     {
         public JapaneseCalendar() { }

src/System.Runtime/src/ApiCompatBaseline.uapaot.txt

@@ -1,4 +1,5 @@
 Compat issues with assembly System.Runtime:
 TypesMustExist : Type 'System.Runtime.CompilerServices.CallerArgumentExpressionAttribute' does not exist in the implementation but it does exist in the contract.
 CannotMakeMoreVisible : Visibility of member 'System.Exception.HResult.set(System.Int32)' is 'Family' in the implementation but 'Public' in the contract.
+TypesMustExist : Type 'System.Globalization.ISOWeek' does not exist in the implementation but it does exist in the contract.