Update RelativeDate.cs

dev/DevWinUI/Common/RelativeDate/RelativeDate.cs

@@ -6,26 +6,37 @@ namespace DevWinUI;
 public readonly struct RelativeDate : IComparable, IComparable<RelativeDate>, IEquatable<RelativeDate>, IFormattable
 {
     public readonly ResourceHelper resourceHelper;
+    private TimeProvider TimeProvider { get; }
     private DateTime DateTime { get; }
 
-    public RelativeDate(DateTime dateTime)
+    public RelativeDate(DateTime dateTime, TimeProvider? timeProvider)
     {
         if (dateTime.Kind == DateTimeKind.Unspecified)
-            throw new ArgumentException("Cannot determine is the argument is a local datetime or UTC datetime", nameof(dateTime));
+            throw new ArgumentException("Cannot determine if the argument is a local datetime or UTC datetime", nameof(dateTime));
+
         resourceHelper = new ResourceHelper();
-        DateTime = dateTime;
+        DateTime = dateTime.ToUniversalTime();
+        TimeProvider = timeProvider ?? TimeProvider.System;
+    }
+
+    public RelativeDate(DateTime dateTime)
+        : this(dateTime, timeProvider: null)
+    {
     }
 
     public static RelativeDate Get(DateTime dateTime) => new(dateTime);
 
     public static RelativeDate Get(DateTimeOffset dateTime) => new(dateTime.UtcDateTime);
 
+    public static RelativeDate Get(DateTime dateTime, TimeProvider? timeProvider) => new(dateTime, timeProvider);
+
+    public static RelativeDate Get(DateTimeOffset dateTime, TimeProvider? timeProvider) => new(dateTime.UtcDateTime, timeProvider);
+
     public override string ToString() => ToString(format: null, formatProvider: null);
 
     public string ToString(string? format, IFormatProvider? formatProvider)
     {
-        var now = DateTime.Kind == DateTimeKind.Utc ? DateTimeService.UtcNow : DateTimeService.Now;
-
+        var now = TimeProvider.GetUtcNow().UtcDateTime;
         var delta = now - DateTime;
         var culture = formatProvider as CultureInfo;