added tests for out of order dispose scenario

src/Pool.Tests/Fakes/Echo.cs

@@ -1,18 +1,47 @@
-namespace Pool.Tests.Fakes;
+using System.Runtime.CompilerServices;
+
+namespace Pool.Tests.Fakes;
 
 internal sealed class Echo
     : IEcho
+    , IDisposable
 {
+    private bool disposed;
+
     public bool IsReady { get; private set; }
 
     public Task MakeReadyAsync(CancellationToken cancellationToken)
     {
+        ThrowIfDisposed();
+
         IsReady = true;
         return Task.CompletedTask;
     }
 
-    public string Shout(string message)
+    public string Shout(string message) => message;
+
+    public void Dispose()
+    {
+        if (disposed)
+        {
+            return;
+        }
+
+        disposed = true;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private void ThrowIfDisposed()
     {
-        return message;
+#if NET7_0_OR_GREATER
+#pragma warning disable IDE0022 // Use expression body for method
+        ObjectDisposedException.ThrowIf(disposed, nameof(Echo));
+#pragma warning restore IDE0022 // Use expression body for method
+#elif NET6_0_OR_GREATER                                                      
+        if (disposed)
+        {
+            throw new ObjectDisposedException(nameof(Echo));
+        }
+#endif
     }
 }

src/Pool.Tests/Fakes/EchoFactory.cs

@@ -4,24 +4,15 @@ namespace Pool.Tests.Fakes;
 internal sealed class EchoFactory
     : IPoolItemFactory<IEcho>
     , IReadyCheck<IEcho>
-
 {
-    public IEcho CreateItem()
-    {
-        return new Echo();
-    }
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("IDisposableAnalyzers.Correctness", "IDISP005:Return type should indicate that the value should be disposed", Justification = "items created by the factory are disposed by the pool or the factory")]
+    public IEcho CreateItem() => new Echo();
 
     public async Task<bool> IsReadyAsync(
         IEcho item,
-        CancellationToken cancellationToken)
-    {
-        return await Task.FromResult(item.IsReady);
-    }
+        CancellationToken cancellationToken) => await Task.FromResult(item.IsReady);
 
     public async Task MakeReadyAsync(
         IEcho item,
-        CancellationToken cancellationToken)
-    {
-        await item.MakeReadyAsync(cancellationToken);
-    }
+        CancellationToken cancellationToken) => await item.MakeReadyAsync(cancellationToken);
 }

src/Pool.Tests/GlobalSuppressions.cs

@@ -7,3 +7,4 @@
 
 [assembly: SuppressMessage("Naming", "CA1707:Identifiers should not contain underscores", Justification = "unit test naming")]
 [assembly: SuppressMessage("Style", "IDE1006:Naming Styles", Justification = "unit test naming")]
+[assembly: SuppressMessage("CodeQuality", "IDE0079:Remove unnecessary suppression", Justification = "not unnecessary")]

src/Pool.Tests/Pool.Tests.csproj

@@ -17,7 +17,7 @@
 		</PackageReference>
 		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
 		<PackageReference Include="xunit" Version="2.8.0" />
-		<PackageReference Include="Xunit.DependencyInjection" Version="9.2.1" />
+		<PackageReference Include="Xunit.DependencyInjection" Version="9.3.0" />
 		<PackageReference Include="xunit.runner.visualstudio" Version="2.8.0">
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 			<PrivateAssets>all</PrivateAssets>

src/Pool.Tests/PoolItemFactoryTests.cs

@@ -0,0 +1,29 @@
+using Microsoft.Extensions.DependencyInjection;
+using Pool.Tests.Fakes;
+
+namespace Pool.Tests;
+
+public sealed class PoolItemFactoryTests
+{
+    [Fact]
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("IDisposableAnalyzers.Correctness", "IDISP017:Prefer using", Justification = "required for test")]
+    public async Task PoolItemFactory_Doesnt_Crash_On_Dispose()
+    {
+        using var services = new ServiceCollection()
+            .AddScoped<IEcho, Echo>()
+            .BuildServiceProvider();
+
+        var factory = new DefaultPoolItemFactory<IEcho>(services);
+        var pool = new Pool<IEcho>(factory, new DefaultReadyCheck<IEcho>(), new PoolOptions { MinSize = 5 });
+        var item = await pool.LeaseAsync(CancellationToken.None);
+        Assert.NotNull(item);
+
+        await pool.ReleaseAsync(item);
+
+        // pool disposes all the items on the queue
+        pool.Dispose();
+
+        // factory disposes the scope, which also disposes the items, so the items need to protect themselves with dispose pattern
+        factory.Dispose();
+    }
+}

src/Pool.Tests/PoolTests.cs

@@ -5,28 +5,16 @@ namespace Pool.Tests;
 public sealed class PoolTests(IPool<IEcho> pool)
 {
     [Fact]
-    public void Pool_Is_Injected()
-    {
-        Assert.NotNull(pool);
-    }
+    public void Pool_Is_Injected() => Assert.NotNull(pool);
 
     [Fact]
-    public void Allocated_Matches_Min()
-    {
-        Assert.Equal(1, pool.ItemsAllocated);
-    }
+    public void Allocated_Matches_Min() => Assert.Equal(1, pool.ItemsAllocated);
 
     [Fact]
-    public void Available_Matches_Allocated()
-    {
-        Assert.Equal(pool.ItemsAllocated, pool.ItemsAvailable);
-    }
+    public void Available_Matches_Allocated() => Assert.Equal(pool.ItemsAllocated, pool.ItemsAvailable);
 
     [Fact]
-    public void Backlog_Is_Empty()
-    {
-        Assert.Equal(0, pool.QueuedLeases);
-    }
+    public void Backlog_Is_Empty() => Assert.Equal(0, pool.QueuedLeases);
 
     [Fact]
     public async Task Lease_And_Release()

src/Pool.Tests/Startup.cs

@@ -9,9 +9,7 @@ public sealed class Startup
 {
     private readonly IConfiguration configuration;
 
-    public Startup()
-    {
-        configuration = new ConfigurationBuilder()
+    public Startup() => configuration = new ConfigurationBuilder()
             .AddInMemoryCollection(new Dictionary<string, string>
             {
                 { "PoolOptions:MinSize", "1" },
@@ -20,13 +18,8 @@ public Startup()
                 { "PoolOptions:ReadyTimeout", "00:00:00.01" },
             }!)
             .Build();
-    }
 
-    public void ConfigureServices(IServiceCollection services)
-    {
-        _ = services
+    public void ConfigureServices(IServiceCollection services) => _ = services
             .AddTransientPool<IEcho, EchoFactory>(configuration)
             .AddReadyCheck<IEcho, EchoFactory>();
-
-    }
 }