Fix disposable extensions bugs and add relevant tests.

CodeJam.Main.Tests/CodeJam.Main.Tests.csproj

@@ -10,6 +10,7 @@
 		<TargetFrameworks Condition=" '$(NetFrameworkTests)' == 'true' ">net48;net472;net471;net47;net461;net45;net40;net35</TargetFrameworks>
 		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
 		<DisableImplicitNuGetFallbackFolder>true</DisableImplicitNuGetFallbackFolder>
+		<LangVersion>12.0</LangVersion>
 	</PropertyGroup>
 
 	<!-- #region Targeting -->

CodeJam.Main.Tests/DisposableExtensionsTests.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+using NUnit.Framework;
+
+namespace CodeJam;
+
+[TestFixture(Category = "Disposable")]
+[SuppressMessage("ReSharper", "HeapView.CanAvoidClosure")]
+public static class DisposableExtensionsTests
+{
+	[Test]
+	public static void DisposeAllMustReleaseAllObjects()
+	{
+		const int expectedDisposeCount = 10;
+
+		int actualDisposeCount = 0;
+
+		var objectsForDispose = Enumerable
+			.Range(0, expectedDisposeCount)
+			.Select(x => Disposable.Create(() => ++actualDisposeCount));
+
+		objectsForDispose.DisposeAll();
+
+		Assert.AreEqual(expectedDisposeCount, actualDisposeCount);
+	}
+
+	[Test]
+	public static void DisposeAllMustCollectAllExceptions()
+	{
+		const int expectedExceptionCount = 7;
+
+		var objectsWithException = Enumerable
+			.Range(0, expectedExceptionCount)
+			.Select(x => Disposable.Create(() => throw new Exception()));
+
+		const int expectedSuccessCount = 3;
+
+		var objectsWithoutException = Enumerable
+			.Range(0, expectedSuccessCount)
+			.Select(x => Disposable.Create(() => { }));
+
+		var objectsForDispose = objectsWithException.Concat(objectsWithoutException).ToArray();
+
+		int actualExceptionCount = -1;
+
+		try
+		{
+			objectsForDispose.DisposeAll();
+		}
+		catch (AggregateException ex)
+		{
+			actualExceptionCount = ex.InnerExceptions.Count;
+		}
+
+		Assert.AreEqual(expectedExceptionCount, actualExceptionCount);
+	}
+
+#if NETSTANDARD21_OR_GREATER || NETCOREAPP30_OR_GREATER
+	[Test]
+	public static async Task DisposeAsyncMustCallDiposeOnce()
+	{
+		const int expectedDisposeCount = 1;
+
+		int actualDisposeCount = 0;
+
+		var objectForDispose = Disposable.Create(() => ++actualDisposeCount);
+
+		await objectForDispose.DisposeAsync();
+
+		Assert.AreEqual(expectedDisposeCount, actualDisposeCount);
+	}
+
+	[Test]
+	public static void DisposeAsyncMustNotBlockThread()
+	{
+		var disposeDuration = new TimeSpan(0, 0, 1);
+
+		var longDisposableObject = Disposable.Create(() => Thread.Sleep(disposeDuration));
+
+		var startTime = DateTime.Now;
+
+		var task = longDisposableObject.DisposeAsync();
+
+		var callDuration = DateTime.Now - startTime;
+
+		Assert.Less(callDuration, disposeDuration);
+	}
+#endif
+}

CodeJam.Main/DisposableExtensions.cs

@@ -1,8 +1,7 @@
 using System;
 using System.Collections.Generic;
-#if NETSTANDARD21_OR_GREATER || NETCOREAPP30_OR_GREATER
 using System.Threading.Tasks;
-#endif
+
 using CodeJam.Internal;
 
 using JetBrains.Annotations;
@@ -30,7 +29,8 @@ public static void DisposeAll([InstantHandle] this IEnumerable<IDisposable> disp
 				}
 				catch (Exception ex)
 				{
-					exceptions = new List<Exception> { ex };
+					if (exceptions != null) exceptions.Add(ex);
+					else exceptions = new List<Exception> { ex };
 				}
 			}
 
@@ -66,14 +66,12 @@ public static void DisposeAll(
 		/// Calls DisposeAsync if <paramref name="disposable"/> implements <see cref="IAsyncDisposable"/>, otherwise
 		/// calls <see cref="IDisposable.Dispose"/>
 		/// </summary>
-		public static ValueTask DisposeAsync(this IDisposable disposable)
+		public static async ValueTask DisposeAsync(this IDisposable disposable)
 		{
 			Code.NotNull(disposable, nameof(disposable));
 			if (disposable is IAsyncDisposable asyncDisposable)
-				return asyncDisposable.DisposeAsync();
-
-			disposable.Dispose();
-			return new ValueTask();
+				await asyncDisposable.DisposeAsync();
+			await new ValueTask(Task.Run(() => disposable.Dispose()));
 		}
 #endif
 	}