feat: notify on time changes in MockTimeSystem

Source/Testably.Abstractions.Testing/TimeSystem/ITimeProvider.cs

@@ -18,6 +18,14 @@ public interface ITimeProvider
 	/// </summary>
 	DateTime MinValue { get; set; }
 
+	/// <summary>
+	///     The start time of the time provider.
+	/// </summary>
+	/// <remarks>
+	///     This is the time, the time provider was initialized at the beginning of the test.
+	/// </remarks>
+	DateTime StartTime { get; }
+
 	/// <summary>
 	///     Gets or sets the <see cref="IDateTime.UnixEpoch" />
 	/// </summary>

Source/Testably.Abstractions.Testing/TimeSystem/TimeProviderMock.cs

@@ -20,7 +20,7 @@ public TimeProviderMock(DateTime now, string description)
 		_now = now.Kind == DateTimeKind.Unspecified
 			? DateTime.SpecifyKind(now, DateTimeKind.Utc)
 			: now;
-
+		StartTime = _now;
 		_description = description;
 	}
 
@@ -41,6 +41,9 @@ public TimeProviderMock(DateTime now, string description)
 	public DateTime UnixEpoch { get; set; } = DateTime.UnixEpoch;
 #endif
 
+	/// <inheritdoc cref="ITimeProvider.StartTime" />
+	public DateTime StartTime { get; }
+
 	/// <inheritdoc cref="ITimeProvider.AdvanceBy(TimeSpan)" />
 	public void AdvanceBy(TimeSpan interval)
 	{

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_net10.0.txt

@@ -427,6 +427,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_net6.0.txt

@@ -417,6 +417,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_net8.0.txt

@@ -427,6 +427,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_net9.0.txt

@@ -427,6 +427,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_netstandard2.0.txt

@@ -397,6 +397,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Api/Testably.Abstractions.Api.Tests/Expected/Testably.Abstractions.Testing_netstandard2.1.txt

@@ -410,6 +410,7 @@ namespace Testably.Abstractions.Testing.TimeSystem
     {
         System.DateTime MaxValue { get; set; }
         System.DateTime MinValue { get; set; }
+        System.DateTime StartTime { get; }
         System.DateTime UnixEpoch { get; set; }
         void AdvanceBy(System.TimeSpan interval);
         System.DateTime Read();

Tests/Testably.Abstractions.Testing.Tests/MockTimeSystemTests.cs

@@ -11,7 +11,8 @@ public async Task Delay_Infinite_ShouldNotThrowException()
 		MockTimeSystem timeSystem = new();
 		Exception? exception =
 			await Record.ExceptionAsync(()
-				=> timeSystem.Task.Delay(Timeout.Infinite, TestContext.Current!.Execution.CancellationToken));
+				=> timeSystem.Task.Delay(Timeout.Infinite,
+					TestContext.Current!.Execution.CancellationToken));
 
 		await That(exception).IsNull();
 	}
@@ -56,14 +57,16 @@ async Task Act()
 	[Arguments(DateTimeKind.Local)]
 	[Arguments(DateTimeKind.Unspecified)]
 	[Arguments(DateTimeKind.Utc)]
-	public async Task DifferenceBetweenDateTimeNowAndDateTimeUtcNow_ShouldBeLocalTimeZoneOffsetFromUtc(DateTimeKind dateTimeKind)
+	public async Task
+		DifferenceBetweenDateTimeNowAndDateTimeUtcNow_ShouldBeLocalTimeZoneOffsetFromUtc(
+			DateTimeKind dateTimeKind)
 	{
 		DateTime now = TimeTestHelper.GetRandomTime(DateTimeKind.Local);
 
-		var expectedDifference = TimeZoneInfo.Local.GetUtcOffset(now);
+		TimeSpan expectedDifference = TimeZoneInfo.Local.GetUtcOffset(now);
 
 		MockTimeSystem timeSystem = new(DateTime.SpecifyKind(now, dateTimeKind));
-		var actualDifference = timeSystem.DateTime.Now - timeSystem.DateTime.UtcNow;
+		TimeSpan actualDifference = timeSystem.DateTime.Now - timeSystem.DateTime.UtcNow;
 
 		await That(actualDifference).IsEqualTo(expectedDifference);
 	}
@@ -109,6 +112,17 @@ public async Task Sleep_LessThanInfiniteTimeSpan_ShouldThrowArgumentOutOfRangeEx
 		await That(exception).IsExactly<ArgumentOutOfRangeException>();
 	}
 
+	[Test]
+	public async Task TimeProvider_StartTime_ShouldBeSetToInitialTime()
+	{
+		DateTime now = TimeTestHelper.GetRandomTime(DateTimeKind.Utc);
+		MockTimeSystem timeSystem = new(TimeProvider.Use(now));
+
+		timeSystem.TimeProvider.AdvanceBy(TimeSpan.FromMinutes(42));
+
+		await That(timeSystem.TimeProvider.StartTime).IsEqualTo(now);
+	}
+
 	[Test]
 	public async Task ToString_WithFixedContainer_ShouldContainTimeProvider()
 	{