feat: Add Fake Time Provider extension generator

Introduces a source generator that creates a `WithFakeTimeProvider()` extension method for `AutoMocker`.

This streamlines deterministic testing of time-sensitive components by automatically registering `FakeTimeProvider` from `Microsoft.Extensions.TimeProvider.Testing`. It registers the fake provider as both `TimeProvider` (for injection) and `FakeTimeProvider` (for test control).

Includes new documentation and example tests across various test frameworks.

Author: Keboo

Directory.Packages.props

@@ -23,6 +23,7 @@
     <PackageVersion Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageVersion Include="OpenTelemetry.Api" Version="1.15.3" />
     <PackageVersion Include="OpenTelemetry.Exporter.InMemory" Version="1.15.3" />
+    <PackageVersion Include="Microsoft.Extensions.TimeProvider.Testing" Version="10.0.0" />
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="10.0.8" />
     <PackageVersion Include="System.Formats.Asn1" Version="10.0.8" />
     <PackageVersion Include="TUnit" Version="1.46.0" />

GeneratorTests/Moq.AutoMock.Generator.DisableTests/GeneratorDisableTests.cs

@@ -59,6 +59,17 @@ public void ApplicationInsightsGenerator_WhenDisabled_ExtensionMethodDoesNotExis
             "WithApplicationInsights extension method should not exist when EnableMoqAutoMockerApplicationInsightsGenerator=false");
     }
 
+    [Fact]
+    public void FakeTimeProviderGenerator_WhenDisabled_ExtensionMethodDoesNotExist()
+    {
+        // When EnableMoqAutoMockerFakeTimeProviderGenerator=false, the fake time provider
+        // extension methods should not be generated
+        
+        bool hasGeneratedTimeProviderExtension = HasExtensionMethod("WithFakeTimeProvider");
+        Assert.False(hasGeneratedTimeProviderExtension,
+            "WithFakeTimeProvider extension method should not exist when EnableMoqAutoMockerFakeTimeProviderGenerator=false");
+    }
+
     /// <summary>
     /// Checks if an extension method with the given name exists for the AutoMocker type
     /// in the current assembly (generated code is added to the consuming project).

GeneratorTests/Moq.AutoMock.Generator.DisableTests/Moq.AutoMock.Generator.DisableTests.csproj

@@ -12,6 +12,7 @@
     <EnableMoqAutoMockerKeyedServicesGenerator>false</EnableMoqAutoMockerKeyedServicesGenerator>
     <EnableMoqAutoMockerFakeLoggingGenerator>false</EnableMoqAutoMockerFakeLoggingGenerator>
     <EnableMoqAutoMockerApplicationInsightsGenerator>false</EnableMoqAutoMockerApplicationInsightsGenerator>
+    <EnableMoqAutoMockerFakeTimeProviderGenerator>false</EnableMoqAutoMockerFakeTimeProviderGenerator>
   </PropertyGroup>
 
   <ItemGroup>
@@ -20,6 +21,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" />
     <PackageReference Include="Microsoft.ApplicationInsights" />
+    <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" />
     <PackageReference Include="xunit.v3" />
     <PackageReference Include="xunit.runner.visualstudio">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -56,6 +58,7 @@
     <CompilerVisibleProperty Include="EnableMoqAutoMockerKeyedServicesGenerator" />
     <CompilerVisibleProperty Include="EnableMoqAutoMockerFakeLoggingGenerator" />
     <CompilerVisibleProperty Include="EnableMoqAutoMockerApplicationInsightsGenerator" />
+    <CompilerVisibleProperty Include="EnableMoqAutoMockerFakeTimeProviderGenerator" />
   </ItemGroup>
 
 </Project>

GeneratorTests/Moq.AutoMock.Generator.Example.MSTest/ControllerWithTimeProviderTests.cs

@@ -0,0 +1,39 @@
+using Microsoft.Extensions.Time.Testing;
+
+namespace Moq.AutoMock.Generator.Example.MSTest;
+
+[TestClass]
+public class ControllerWithTimeProviderTests
+{
+    [TestMethod]
+    public void CreateInstance_WithFakeTimeProvider_CreatesController()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.IsNotNull(controller);
+    }
+
+    [TestMethod]
+    public void CreateInstance_WithFakeTimeProvider_UsesControlledTime()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        var fakeTimeProvider = mocker.Get<FakeTimeProvider>();
+        var startTime = new DateTimeOffset(2025, 1, 1, 12, 0, 0, TimeSpan.Zero);
+        fakeTimeProvider.SetUtcNow(startTime);
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.AreEqual(startTime, controller.GetCurrentTime());
+
+        fakeTimeProvider.Advance(TimeSpan.FromHours(1));
+
+        Assert.AreEqual(startTime.AddHours(1), controller.GetCurrentTime());
+    }
+}

GeneratorTests/Moq.AutoMock.Generator.Example.MSTest/Moq.AutoMock.Generator.Example.MSTest.csproj

@@ -11,6 +11,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.Testing" />
+    <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" />
     <PackageReference Include="MSTest" />
     <PackageReference Include="coverlet.collector">
       <PrivateAssets>all</PrivateAssets>

GeneratorTests/Moq.AutoMock.Generator.Example.NUnit/ControllerWithTimeProviderTests.cs

@@ -0,0 +1,39 @@
+using Microsoft.Extensions.Time.Testing;
+using NUnit.Framework;
+
+namespace Moq.AutoMock.Generator.Example.NUnit;
+
+public class ControllerWithTimeProviderTests
+{
+    [Test]
+    public void CreateInstance_WithFakeTimeProvider_CreatesController()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.That(controller, Is.Not.Null);
+    }
+
+    [Test]
+    public void CreateInstance_WithFakeTimeProvider_UsesControlledTime()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        var fakeTimeProvider = mocker.Get<FakeTimeProvider>();
+        var startTime = new DateTimeOffset(2025, 1, 1, 12, 0, 0, TimeSpan.Zero);
+        fakeTimeProvider.SetUtcNow(startTime);
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.That(controller.GetCurrentTime(), Is.EqualTo(startTime));
+
+        fakeTimeProvider.Advance(TimeSpan.FromHours(1));
+
+        Assert.That(controller.GetCurrentTime(), Is.EqualTo(startTime.AddHours(1)));
+    }
+}

GeneratorTests/Moq.AutoMock.Generator.Example.NUnit/Moq.AutoMock.Generator.Example.NUnit.csproj

@@ -11,6 +11,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.Testing" />
+    <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" />
     <PackageReference Include="NUnit" />
     <PackageReference Include="NUnit3TestAdapter" />
     <PackageReference Include="coverlet.collector">

GeneratorTests/Moq.AutoMock.Generator.Example.TUnit/ControllerWithTimeProviderTests.cs

@@ -0,0 +1,38 @@
+using Microsoft.Extensions.Time.Testing;
+
+namespace Moq.AutoMock.Generator.Example.TUnit;
+
+public partial class ControllerWithTimeProviderTests
+{
+    [Test]
+    public async Task CreateInstance_WithFakeTimeProvider_CreatesController()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        await Assert.That(controller).IsNotNull();
+    }
+
+    [Test]
+    public async Task CreateInstance_WithFakeTimeProvider_UsesControlledTime()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        var fakeTimeProvider = mocker.Get<FakeTimeProvider>();
+        var startTime = new DateTimeOffset(2025, 1, 1, 12, 0, 0, TimeSpan.Zero);
+        fakeTimeProvider.SetUtcNow(startTime);
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        await Assert.That(controller.GetCurrentTime()).IsEqualTo(startTime);
+
+        fakeTimeProvider.Advance(TimeSpan.FromHours(1));
+
+        await Assert.That(controller.GetCurrentTime()).IsEqualTo(startTime.AddHours(1));
+    }
+}

GeneratorTests/Moq.AutoMock.Generator.Example.TUnit/Moq.AutoMock.Generator.Example.TUnit.csproj

@@ -11,6 +11,7 @@
   <ItemGroup>
     <PackageReference Include="TUnit" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.Testing" />
+    <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" />
   </ItemGroup>
 
   <ItemGroup>

GeneratorTests/Moq.AutoMock.Generator.Example.xUnit/ControllerWithTimeProviderTests.cs

@@ -0,0 +1,39 @@
+using Microsoft.Extensions.Time.Testing;
+using Xunit;
+
+namespace Moq.AutoMock.Generator.Example.xUnit;
+
+public class ControllerWithTimeProviderTests
+{
+    [Fact]
+    public void CreateInstance_WithFakeTimeProvider_CreatesController()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.NotNull(controller);
+    }
+
+    [Fact]
+    public void CreateInstance_WithFakeTimeProvider_UsesControlledTime()
+    {
+        AutoMocker mocker = new();
+
+        mocker.WithFakeTimeProvider();
+
+        var fakeTimeProvider = mocker.Get<FakeTimeProvider>();
+        var startTime = new DateTimeOffset(2025, 1, 1, 12, 0, 0, TimeSpan.Zero);
+        fakeTimeProvider.SetUtcNow(startTime);
+
+        ControllerWithTimeProvider controller = mocker.CreateInstance<ControllerWithTimeProvider>();
+
+        Assert.Equal(startTime, controller.GetCurrentTime());
+
+        fakeTimeProvider.Advance(TimeSpan.FromHours(1));
+
+        Assert.Equal(startTime.AddHours(1), controller.GetCurrentTime());
+    }
+}