From 3b838a4dae264f857bb9ebbe1220b179603ceb8d Mon Sep 17 00:00:00 2001
From: Zhiyuan Liang <141655842+zhiyuanliang-ms@users.noreply.github.com>
Date: Fri, 16 Aug 2024 01:21:27 +0800
Subject: [PATCH] use TimeProvider (#452)

---
 .../FeatureFilters/ISystemClock.cs            | 20 -------------------
 .../FeatureFilters/TimeWindowFilter.cs        |  6 +++---
 .../Microsoft.FeatureManagement.csproj        |  3 ++-
 .../Tests.FeatureManagement/OnDemandClock.cs  | 10 +++++++---
 4 files changed, 12 insertions(+), 27 deletions(-)
 delete mode 100644 src/Microsoft.FeatureManagement/FeatureFilters/ISystemClock.cs

diff --git a/src/Microsoft.FeatureManagement/FeatureFilters/ISystemClock.cs b/src/Microsoft.FeatureManagement/FeatureFilters/ISystemClock.cs
deleted file mode 100644
index 1fc9b667..00000000
--- a/src/Microsoft.FeatureManagement/FeatureFilters/ISystemClock.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT license.
-//
-
-using System;
-
-namespace Microsoft.FeatureManagement.FeatureFilters
-{
-    /// <summary>
-    /// Abstracts the system clock to facilitate testing.
-    /// .NET8 offers an abstract class TimeProvider. After we stop supporting .NET version less than .NET8, this ISystemClock should retire.
-    /// </summary>
-    internal interface ISystemClock
-    {
-        /// <summary>
-        /// Retrieves the current system time in UTC.
-        /// </summary>
-        public DateTimeOffset UtcNow { get; }
-    }
-}
diff --git a/src/Microsoft.FeatureManagement/FeatureFilters/TimeWindowFilter.cs b/src/Microsoft.FeatureManagement/FeatureFilters/TimeWindowFilter.cs
index fb1f6f01..62b5f4a5 100644
--- a/src/Microsoft.FeatureManagement/FeatureFilters/TimeWindowFilter.cs
+++ b/src/Microsoft.FeatureManagement/FeatureFilters/TimeWindowFilter.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);
 
diff --git a/src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj b/src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj
index 62e3ed9d..3abf1568 100644
--- a/src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj
+++ b/src/Microsoft.FeatureManagement/Microsoft.FeatureManagement.csproj
@@ -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" />
diff --git a/tests/Tests.FeatureManagement/OnDemandClock.cs b/tests/Tests.FeatureManagement/OnDemandClock.cs
index c639a3e3..59c8c0d8 100644
--- a/tests/Tests.FeatureManagement/OnDemandClock.cs
+++ b/tests/Tests.FeatureManagement/OnDemandClock.cs
@@ -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;
+        }
     }
 }