Refine integreation of TimeProvider

src/Polly.Core/PublicAPI.Unshipped.txt

@@ -7,6 +7,6 @@ Polly.CircuitBreaker.BreakDurationGeneratorArguments.FailureCount.get -> int
 Polly.CircuitBreaker.BreakDurationGeneratorArguments.FailureRate.get -> double
 Polly.CircuitBreaker.CircuitBreakerStrategyOptions<TResult>.BreakDurationGenerator.get -> System.Func<Polly.CircuitBreaker.BreakDurationGeneratorArguments, System.Threading.Tasks.ValueTask<System.TimeSpan>>?
 Polly.CircuitBreaker.CircuitBreakerStrategyOptions<TResult>.BreakDurationGenerator.set -> void
-Polly.ResiliencePipelineBuilderBase.TimeProvider.get -> System.TimeProvider!
+Polly.ResiliencePipelineBuilderBase.TimeProvider.get -> System.TimeProvider?
 Polly.ResiliencePipelineBuilderBase.TimeProvider.set -> void
 Polly.StrategyBuilderContext.TimeProvider.get -> System.TimeProvider!

src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs

@@ -59,7 +59,7 @@ private Builder CreateBuilder()
         builder.InstanceName = _instanceName;
         _configure(builder, context);
 
-        var timeProvider = builder.TimeProvider;
+        var timeProvider = builder.GetTimeProvider();
         var telemetry = new ResilienceStrategyTelemetry(
             new ResilienceTelemetrySource(builder.Name, builder.InstanceName, null),
             builder.TelemetryListener);

src/Polly.Core/ResiliencePipelineBuilderBase.cs

@@ -71,10 +71,9 @@ private protected ResiliencePipelineBuilderBase(ResiliencePipelineBuilderBase ot
     /// Gets or sets a <see cref="TimeProvider"/> that is used by strategies that work with time.
     /// </summary>
     /// <value>
-    /// The default value is <see cref="TimeProvider.System"/>.
+    /// The default value is <see langword="null"/> and unless set, the <see cref="TimeProvider.System"/> will be used.
     /// </value>
-    [Required]
-    public TimeProvider TimeProvider { get; set; } = TimeProvider.System;
+    public TimeProvider? TimeProvider { get; set; }
 
     /// <summary>
     /// Gets or sets the <see cref="Polly.Telemetry.TelemetryListener"/> that is used by Polly to report resilience events.
@@ -129,13 +128,15 @@ internal PipelineComponent BuildPipelineComponent()
 
         var source = new ResilienceTelemetrySource(Name, InstanceName, null);
 
-        return PipelineComponentFactory.CreateComposite(components, new ResilienceStrategyTelemetry(source, TelemetryListener), TimeProvider);
+        return PipelineComponentFactory.CreateComposite(components, new ResilienceStrategyTelemetry(source, TelemetryListener), GetTimeProvider());
     }
 
+    internal TimeProvider GetTimeProvider() => TimeProvider ?? TimeProvider.System;
+
     private PipelineComponent CreateComponent(Entry entry)
     {
         var source = new ResilienceTelemetrySource(Name, InstanceName, entry.Options.Name);
-        var context = new StrategyBuilderContext(new ResilienceStrategyTelemetry(source, TelemetryListener), TimeProvider);
+        var context = new StrategyBuilderContext(new ResilienceStrategyTelemetry(source, TelemetryListener), GetTimeProvider());
 
         var strategy = entry.Factory(context);
         strategy.Options = entry.Options;

src/Polly.Extensions/DependencyInjection/PollyServiceCollectionExtensions.cs

@@ -245,6 +245,12 @@ private static void AddResiliencePipelineBuilder(this IServiceCollection service
         {
             var builder = new ResiliencePipelineBuilder();
             builder.ConfigureTelemetry(serviceProvider.GetRequiredService<IOptions<TelemetryOptions>>().Value);
+
+            if (serviceProvider.GetService<TimeProvider>() is { } timeProvider)
+            {
+                builder.TimeProvider = timeProvider;
+            }
+
             return builder;
         });
     }

src/Polly.Testing/PublicAPI.Unshipped.txt

@@ -1,3 +1 @@
 #nullable enable
-Polly.TestingResiliencePipelineBuilderExtensions
-static Polly.TestingResiliencePipelineBuilderExtensions.WithTimeProvider<TBuilder>(this TBuilder! builder, System.TimeProvider! timeProvider) -> TBuilder!

test/Polly.Core.Tests/GenericResiliencePipelineBuilderTests.cs

@@ -12,7 +12,7 @@ public class GenericResiliencePipelineBuilderTests
     public void Ctor_EnsureDefaults()
     {
         _builder.Name.Should().BeNull();
-        _builder.TimeProvider.Should().Be(TimeProvider.System);
+        _builder.TimeProvider.Should().BeNull();
     }
 
     [Fact]

test/Polly.Core.Tests/ResiliencePipelineBuilderTests.cs

@@ -16,7 +16,19 @@ public void Ctor_EnsureDefaults()
         var builder = new ResiliencePipelineBuilder();
 
         builder.Name.Should().BeNull();
-        builder.TimeProvider.Should().Be(TimeProvider.System);
+        builder.TimeProvider.Should().BeNull();
+    }
+
+    [Fact]
+    public void GetTimeProvider_Ok()
+    {
+        var builder = new ResiliencePipelineBuilder();
+        builder.GetTimeProvider().Should().Be(TimeProvider.System);
+
+        var timeProvider = Substitute.For<TimeProvider>();
+        builder.TimeProvider = timeProvider;
+
+        builder.TimeProvider.Should().Be(timeProvider);
     }
 
     [Fact]

test/Polly.Extensions.Tests/DependencyInjection/PollyServiceCollectionExtensionTests.cs

@@ -1,8 +1,10 @@
 using System.Globalization;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
+using NSubstitute;
 using Polly.DependencyInjection;
 using Polly.Registry;
 using Polly.Telemetry;
@@ -14,7 +16,7 @@ public class PollyServiceCollectionExtensionTests
     private const string Key = "my-pipeline";
     private ServiceCollection _services;
 
-    public PollyServiceCollectionExtensionTests() => _services = new ServiceCollection();
+    public PollyServiceCollectionExtensionTests() => _services = [];
 
     [Fact]
     public void AddResiliencePipeline_ArgValidation()
@@ -23,7 +25,7 @@ public void AddResiliencePipeline_ArgValidation()
         Assert.Throws<ArgumentNullException>(() => AddResiliencePipeline(Key));
         Assert.Throws<ArgumentNullException>(() => AddResiliencePipeline<string>(Key));
 
-        _services = new ServiceCollection();
+        _services = [];
         Assert.Throws<ArgumentNullException>(() => _services.AddResiliencePipeline(
             Key,
             (Action<ResiliencePipelineBuilder, AddResiliencePipelineContext<string>>)null!));
@@ -250,6 +252,37 @@ public void AddResiliencePipeline_Multiple_Ok()
             .HaveCount(30);
     }
 
+    [InlineData(true)]
+    [InlineData(false)]
+    [Theory]
+    public void AddResiliencePipeline_EnsureTimeProvider(bool timeProviderRegistered)
+    {
+        var timeProvider = Substitute.For<TimeProvider>();
+        var asserted = false;
+
+        if (timeProviderRegistered)
+        {
+            _services.TryAddSingleton(timeProvider);
+        }
+
+        _services.AddResiliencePipeline("dummy", builder =>
+        {
+            if (timeProviderRegistered)
+            {
+                builder.TimeProvider.Should().Be(timeProvider);
+            }
+            else
+            {
+                builder.TimeProvider.Should().BeNull();
+            }
+
+            asserted = true;
+        });
+
+        CreateProvider().GetPipeline("dummy");
+        asserted.Should().BeTrue();
+    }
+
     [Fact]
     public void AddResiliencePipelineRegistry_Ok()
     {