use TimeProvider (#452)

Author: zhiyuanliang-ms

src/Microsoft.FeatureManagement/FeatureFilters/ISystemClock.cs

@@ -39,7 +39,7 @@ public TimeWindowFilter(ILoggerFactory loggerFactory = null)
         /// <summary>
         /// This property allows the time window filter in our test suite to use simulated time.
         /// </summary>
-        internal ISystemClock SystemClock { get; set; }
+        internal TimeProvider SystemClock { get; set; }
 
         /// <summary>
         /// Binds configuration representing filter parameters to <see cref="TimeWindowFilterSettings"/>.
@@ -74,7 +74,7 @@ public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context)
             // Check if prebound settings available, otherwise bind from parameters.
             TimeWindowFilterSettings settings = (TimeWindowFilterSettings)context.Settings ?? (TimeWindowFilterSettings)BindParameters(context.Parameters);
 
-            DateTimeOffset now = SystemClock?.UtcNow ?? DateTimeOffset.UtcNow;
+            DateTimeOffset now = SystemClock?.GetUtcNow() ?? DateTimeOffset.UtcNow;
 
             if (!settings.Start.HasValue && !settings.End.HasValue)
             {
@@ -129,7 +129,7 @@ public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context)
 
         private DateTimeOffset? ReloadClosestStart(TimeWindowFilterSettings settings)
         {
-            DateTimeOffset now = SystemClock?.UtcNow ?? DateTimeOffset.UtcNow;
+            DateTimeOffset now = SystemClock?.GetUtcNow() ?? DateTimeOffset.UtcNow;
 
             DateTimeOffset? closestStart = RecurrenceEvaluator.CalculateClosestStart(now, settings);
 

src/Microsoft.FeatureManagement/FeatureFilters/TimeWindowFilter.cs

@@ -35,10 +35,11 @@
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
-    <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="1.1.1" />
+    <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="8.0.0" />
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Bcl.TimeProvider" Version="8.0.1" />
     <PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="2.1.23" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="2.1.10" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="2.1.1" />

src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj

@@ -1,10 +1,14 @@
-using Microsoft.FeatureManagement.FeatureFilters;
-using System;
+using System;
 
 namespace Tests.FeatureManagement
 {
-    class OnDemandClock : ISystemClock
+    class OnDemandClock : TimeProvider
     {
         public DateTimeOffset UtcNow { get; set; }
+
+        public override DateTimeOffset GetUtcNow()
+        {
+            return UtcNow;
+        }
     }
 }