diff --git a/src/Wolfgang.Etl.TestKit.Xunit/EtlScenarioOfT.cs b/src/Wolfgang.Etl.TestKit.Xunit/EtlScenarioOfT.cs
index 3cc99add..5aa968cb 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/EtlScenarioOfT.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/EtlScenarioOfT.cs
@@ -23,8 +23,8 @@ public sealed class EtlScenario<T>
     where T : notnull
 {
     private readonly T[] _items;
-    private (int Index, System.Exception Exception, bool Skip)? _extractorFault;
-    private (int Index, System.Exception Exception, bool Skip)? _loaderFault;
+    private (int Index, Exception Exception, bool Skip)? _extractorFault;
+    private (int Index, Exception Exception, bool Skip)? _loaderFault;
     private TransformerBase<T, T, Report>? _transformer;
 
 
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAndCancellationAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAndCancellationAsyncContractTests.cs
index ee5fa11e..0a96b172 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAndCancellationAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAndCancellationAsyncContractTests.cs
@@ -204,7 +204,7 @@ public void ExtractAsync_with_null_progress_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.ExtractAsync((IProgress<TProgress>)null!);
+            _ = sut.ExtractAsync(null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
@@ -282,7 +282,7 @@ public void ExtractAsync_with_null_progress_and_token_throws_ArgumentNullExcepti
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.ExtractAsync((IProgress<TProgress>)null!, CancellationToken.None);
+            _ = sut.ExtractAsync(null!, CancellationToken.None);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAsyncContractTests.cs
index 98951a62..763e4c87 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/ExtractWithProgressAsyncContractTests.cs
@@ -91,7 +91,7 @@ public void ExtractAsync_with_null_progress_throws_ArgumentNullException()
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
             // The exception is thrown when the method is called, before enumeration starts.
-            _ = sut.ExtractAsync((IProgress<TProgress>)null!);
+            _ = sut.ExtractAsync(null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/ExtractorBaseContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/ExtractorBaseContractTests.cs
index 368f0760..1328c219 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/ExtractorBaseContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/ExtractorBaseContractTests.cs
@@ -328,7 +328,7 @@ public void ExtractAsync_with_null_progress_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.ExtractAsync((IProgress<TProgress>)null!);
+            _ = sut.ExtractAsync(null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
@@ -443,7 +443,7 @@ public void ExtractAsync_with_null_progress_and_token_throws_ArgumentNullExcepti
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.ExtractAsync((IProgress<TProgress>)null!, CancellationToken.None);
+            _ = sut.ExtractAsync(null!, CancellationToken.None);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAndCancellationAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAndCancellationAsyncContractTests.cs
index cf089350..0bb7ca7e 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAndCancellationAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAndCancellationAsyncContractTests.cs
@@ -213,7 +213,7 @@ public async Task LoadAsync_with_null_progress_throws_ArgumentNullException_Asyn
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>
         (
-            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!)
+            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), null!)
         ).ConfigureAwait(false);
 
         Assert.Equal("progress", ex.ParamName);
@@ -292,7 +292,7 @@ public async Task LoadAsync_with_null_progress_and_token_throws_ArgumentNullExce
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>
         (
-            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!, CancellationToken.None)
+            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), null!, CancellationToken.None)
         ).ConfigureAwait(false);
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAsyncContractTests.cs
index ffa3b418..315d97af 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/LoadWithProgressAsyncContractTests.cs
@@ -76,7 +76,7 @@ public async Task LoadAsync_with_null_progress_throws_ArgumentNullException_Asyn
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>
         (
-            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!)
+            () => sut.LoadAsync(AsyncEnumerable.Empty<TItem>(), null!)
         ).ConfigureAwait(false);
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/LoaderBaseContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/LoaderBaseContractTests.cs
index 8ca5a054..5468014c 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/LoaderBaseContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/LoaderBaseContractTests.cs
@@ -143,7 +143,7 @@ public async Task LoadAsync_with_null_items_throws_ArgumentNullException_Async()
         var sut = CreateSut();
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync((IAsyncEnumerable<TItem>)null!)).ConfigureAwait(false);
+            sut.LoadAsync(null!)).ConfigureAwait(false);
 
         Assert.Equal("items", ex.ParamName);
     }
@@ -217,7 +217,7 @@ public async Task LoadAsync_with_token_and_null_items_throws_ArgumentNullExcepti
         var sut = CreateSut();
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync((IAsyncEnumerable<TItem>)null!, CancellationToken.None)).ConfigureAwait(false);
+            sut.LoadAsync(null!, CancellationToken.None)).ConfigureAwait(false);
 
         Assert.Equal("items", ex.ParamName);
     }
@@ -338,7 +338,7 @@ public async Task LoadAsync_with_progress_and_null_items_throws_ArgumentNullExce
         var progress = new SynchronousProgress<TProgress>(_ => { });
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync((IAsyncEnumerable<TItem>)null!, progress)).ConfigureAwait(false);
+            sut.LoadAsync(null!, progress)).ConfigureAwait(false);
 
         Assert.Equal("items", ex.ParamName);
     }
@@ -353,7 +353,7 @@ public async Task LoadAsync_with_null_progress_throws_ArgumentNullException_Asyn
         var sut = CreateSut();
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync(CreateInputItemsAsync(), (IProgress<TProgress>)null!)).ConfigureAwait(false);
+            sut.LoadAsync(CreateInputItemsAsync(), null!)).ConfigureAwait(false);
 
         Assert.Equal("progress", ex.ParamName);
     }
@@ -473,7 +473,7 @@ public async Task LoadAsync_with_progress_and_token_and_null_items_throws_Argume
         var progress = new SynchronousProgress<TProgress>(_ => { });
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync((IAsyncEnumerable<TItem>)null!, progress, CancellationToken.None)).ConfigureAwait(false);
+            sut.LoadAsync(null!, progress, CancellationToken.None)).ConfigureAwait(false);
 
         Assert.Equal("items", ex.ParamName);
     }
@@ -488,7 +488,7 @@ public async Task LoadAsync_with_progress_and_token_and_null_progress_throws_Arg
         var sut = CreateSut();
 
         var ex = await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            sut.LoadAsync(CreateInputItemsAsync(), (IProgress<TProgress>)null!, CancellationToken.None)).ConfigureAwait(false);
+            sut.LoadAsync(CreateInputItemsAsync(), null!, CancellationToken.None)).ConfigureAwait(false);
 
         Assert.Equal("progress", ex.ParamName);
     }
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAndCancellationAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAndCancellationAsyncContractTests.cs
index 26b99f73..29116a77 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAndCancellationAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAndCancellationAsyncContractTests.cs
@@ -205,7 +205,7 @@ public void TransformAsync_with_null_progress_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!);
+            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
@@ -282,7 +282,7 @@ public void TransformAsync_with_null_progress_and_token_throws_ArgumentNullExcep
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!, CancellationToken.None);
+            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), null!, CancellationToken.None);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAsyncContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAsyncContractTests.cs
index 5f67be11..a9412217 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAsyncContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/TransformWithProgressAsyncContractTests.cs
@@ -76,7 +76,7 @@ public void TransformAsync_with_null_progress_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), (IProgress<TProgress>)null!);
+            _ = sut.TransformAsync(AsyncEnumerable.Empty<TItem>(), null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/src/Wolfgang.Etl.TestKit.Xunit/TransformerBaseContractTests.cs b/src/Wolfgang.Etl.TestKit.Xunit/TransformerBaseContractTests.cs
index 68d9fbcd..f5e18b31 100644
--- a/src/Wolfgang.Etl.TestKit.Xunit/TransformerBaseContractTests.cs
+++ b/src/Wolfgang.Etl.TestKit.Xunit/TransformerBaseContractTests.cs
@@ -170,7 +170,7 @@ public void TransformAsync_with_null_items_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync((IAsyncEnumerable<TItem>)null!);
+            _ = sut.TransformAsync(null!);
         });
 
         Assert.Equal("items", ex.ParamName);
@@ -244,7 +244,7 @@ public void TransformAsync_with_token_and_null_items_throws_ArgumentNullExceptio
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync((IAsyncEnumerable<TItem>)null!, CancellationToken.None);
+            _ = sut.TransformAsync(null!, CancellationToken.None);
         });
 
         Assert.Equal("items", ex.ParamName);
@@ -363,7 +363,7 @@ public void TransformAsync_with_progress_and_null_items_throws_ArgumentNullExcep
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync((IAsyncEnumerable<TItem>)null!, progress);
+            _ = sut.TransformAsync(null!, progress);
         });
 
         Assert.Equal("items", ex.ParamName);
@@ -380,7 +380,7 @@ public void TransformAsync_with_null_progress_throws_ArgumentNullException()
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync(CreateInputItemsAsync(), (IProgress<TProgress>)null!);
+            _ = sut.TransformAsync(CreateInputItemsAsync(), null!);
         });
 
         Assert.Equal("progress", ex.ParamName);
@@ -496,7 +496,7 @@ public void TransformAsync_with_progress_and_token_and_null_items_throws_Argumen
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync((IAsyncEnumerable<TItem>)null!, progress, CancellationToken.None);
+            _ = sut.TransformAsync(null!, progress, CancellationToken.None);
         });
 
         Assert.Equal("items", ex.ParamName);
@@ -513,7 +513,7 @@ public void TransformAsync_with_progress_and_token_and_null_progress_throws_Argu
 
         var ex = Assert.Throws<ArgumentNullException>(() =>
         {
-            _ = sut.TransformAsync(CreateInputItemsAsync(), (IProgress<TProgress>)null!, CancellationToken.None);
+            _ = sut.TransformAsync(CreateInputItemsAsync(), null!, CancellationToken.None);
         });
 
         Assert.Equal("progress", ex.ParamName);
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/ClockSeamTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/ClockSeamTests.cs
index 83d40cb6..c384fbc0 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/ClockSeamTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/ClockSeamTests.cs
@@ -164,7 +164,7 @@ private sealed class ClockLoader : LoaderBase<int, EtlProgress>
 
         protected override async Task LoadWorkerAsync(IAsyncEnumerable<int> items, CancellationToken token)
         {
-            await foreach (var item in items.WithCancellation(token).ConfigureAwait(false))
+            await foreach (var _ in items.WithCancellation(token).ConfigureAwait(false))
             {
                 IncrementCurrentItemCount();
             }
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/RetrySeamTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/RetrySeamTests.cs
index 1d9d9636..57970d64 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/RetrySeamTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/RetrySeamTests.cs
@@ -240,7 +240,7 @@ protected override async IAsyncEnumerable<int> WrapWorkerExecution(
             SeamCallCount++;
             if (WorkerRuns == 1)
             {
-                await foreach (var item in base.WrapWorkerExecution(workerFactory, token).WithCancellation(token))
+                await foreach (var item in base.WrapWorkerExecution(workerFactory, token))
                 {
                     yield return item;
                 }
@@ -427,7 +427,7 @@ protected override async IAsyncEnumerable<int> WrapWorkerExecution(
             SeamCallCount++;
             if (WorkerRuns == 1)
             {
-                await foreach (var item in base.WrapWorkerExecution(workerFactory, token).WithCancellation(token))
+                await foreach (var item in base.WrapWorkerExecution(workerFactory, token))
                 {
                     yield return item;
                 }
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/SystemProgressTimerTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/SystemProgressTimerTests.cs
index 3647160c..564f691d 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/SystemProgressTimerTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/BaseClassTests/SystemProgressTimerTests.cs
@@ -97,12 +97,10 @@ public async Task Start_after_dispose_does_not_throw()
     public async Task Timer_callback_fires_during_extraction()
     {
         var elapsedCount = 0;
-        IProgressTimer? capturedTimer = null;
 
         var sut = new CapturingExtractor(
             onTimerCreated: t =>
             {
-                capturedTimer = t;
                 t.Elapsed += () => Interlocked.Increment(ref elapsedCount);
             },
             intervalMs: 30,
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/AggregateErrorsTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/AggregateErrorsTests.cs
index eb9d4d47..d325a9f7 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/AggregateErrorsTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/AggregateErrorsTests.cs
@@ -219,7 +219,7 @@ private sealed class ErroringLoader : LoaderBase<int, EtlProgress>
 
         protected override async Task LoadWorkerAsync(IAsyncEnumerable<int> items, CancellationToken token)
         {
-            await foreach (var item in items.WithCancellation(token))
+            await foreach (var _ in items.WithCancellation(token))
             {
                 IncrementCurrentItemCount();
             }
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/EtlPipelineTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/EtlPipelineTests.cs
index ca4f22da..9a1f7d5d 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/EtlPipelineTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/EtlPipelineTests/EtlPipelineTests.cs
@@ -314,7 +314,7 @@ public void From_when_stream_is_null_throws_ArgumentNullException()
     {
         Assert.Throws<ArgumentNullException>(() => EtlPipeline
             .Create()
-            .From<int>((IAsyncEnumerable<int>)null!));
+            .From<int>(null!));
     }
 
 
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/NullGuardOnChainedStagesTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/NullGuardOnChainedStagesTests.cs
index 6817af1a..d22b576a 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/NullGuardOnChainedStagesTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/NullGuardOnChainedStagesTests.cs
@@ -70,7 +70,7 @@ public void TransformStage_Load_cancel_null_throws()
     {
         Assert.Throws<ArgumentNullException>
         (
-            () => MidChainStage().Load((ILoadWithCancellationAsync<int>)null!)
+            () => MidChainStage().Load(null!)
         );
     }
 
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/PipelineBehaviorTests.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/PipelineBehaviorTests.cs
index ea408d08..66e068bb 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/PipelineBehaviorTests.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/PipelineBehaviorTests.cs
@@ -113,7 +113,7 @@ public void Bare_Load_when_loader_is_null_throws()
     public void CancelOnly_Load_when_loader_is_null_throws()
     {
         var stage = Pipeline.Extract(new BareExtractor<int>(new[] { 1 }));
-        Assert.Throws<ArgumentNullException>(() => stage.Load((ILoadWithCancellationAsync<int>)null!));
+        Assert.Throws<ArgumentNullException>(() => stage.Load(null!));
     }
 
 
diff --git a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/TestDoubles/Extractors.cs b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/TestDoubles/Extractors.cs
index c6c45c77..ada096e7 100644
--- a/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/TestDoubles/Extractors.cs
+++ b/tests/Wolfgang.Etl.Abstractions.Tests.Unit/PipelineTests/TestDoubles/Extractors.cs
@@ -199,10 +199,10 @@ public async IAsyncEnumerable<T> ExtractAsync(IProgress<TProgress> progress)
     }
 
 
-    public async IAsyncEnumerable<T> ExtractAsync
+    public IAsyncEnumerable<T> ExtractAsync
     (
         IProgress<TProgress> progress,
-        [EnumeratorCancellation] CancellationToken token
+        CancellationToken token
     )
     {
         if (progress is null)
@@ -210,6 +210,18 @@ [EnumeratorCancellation] CancellationToken token
             throw new ArgumentNullException(nameof(progress));
         }
 
+        // Split so the null check runs eagerly at call time rather than being
+        // deferred to the first MoveNextAsync of the iterator (S4456).
+        return ExtractFullCoreAsync(progress, token);
+    }
+
+
+    private async IAsyncEnumerable<T> ExtractFullCoreAsync
+    (
+        IProgress<TProgress> progress,
+        [EnumeratorCancellation] CancellationToken token
+    )
+    {
         FullOverloadWasCalled = true;
         LastReceivedProgress = progress;
         LastReceivedToken = token;
diff --git a/tests/Wolfgang.Etl.TestKit.Tests.DocExamples/DocExampleCompilationTests.cs b/tests/Wolfgang.Etl.TestKit.Tests.DocExamples/DocExampleCompilationTests.cs
index fa255df0..609734a3 100644
--- a/tests/Wolfgang.Etl.TestKit.Tests.DocExamples/DocExampleCompilationTests.cs
+++ b/tests/Wolfgang.Etl.TestKit.Tests.DocExamples/DocExampleCompilationTests.cs
@@ -228,7 +228,7 @@ private static IReadOnlyList<MetadataReference> ReferenceAssemblies()
         var tree = CSharpSyntaxTree.ParseText
         (
             source,
-            new CSharpParseOptions(LanguageVersion.Latest, DocumentationMode.Parse)
+            new CSharpParseOptions(LanguageVersion.Latest)
         );
 
         var docComments = tree.GetRoot()
diff --git a/tests/Wolfgang.Etl.TestKit.Tests.Unit/DelayingExtractorTests.cs b/tests/Wolfgang.Etl.TestKit.Tests.Unit/DelayingExtractorTests.cs
index 44f6935f..90b4ba89 100644
--- a/tests/Wolfgang.Etl.TestKit.Tests.Unit/DelayingExtractorTests.cs
+++ b/tests/Wolfgang.Etl.TestKit.Tests.Unit/DelayingExtractorTests.cs
@@ -28,7 +28,7 @@ public void Constructor_when_delaySelector_is_null_throws_ArgumentNullException(
     {
         Assert.Throws<ArgumentNullException>
         (
-            () => new DelayingExtractor<int>(new[] { 1 }, (Func<int, TimeSpan>)null!)
+            () => new DelayingExtractor<int>(new[] { 1 }, null!)
         );
     }
 
diff --git a/tests/Wolfgang.Etl.TestKit.Tests.Unit/TestExtractorTests.cs b/tests/Wolfgang.Etl.TestKit.Tests.Unit/TestExtractorTests.cs
index 4f4c3cb9..c3fe7512 100644
--- a/tests/Wolfgang.Etl.TestKit.Tests.Unit/TestExtractorTests.cs
+++ b/tests/Wolfgang.Etl.TestKit.Tests.Unit/TestExtractorTests.cs
@@ -757,7 +757,7 @@ public void Constructor_with_indexed_factory_and_timer_when_timer_is_null_throws
     {
         var ex = Assert.Throws<ArgumentNullException>
         (
-            () => new TestExtractorWithTimer((Func<int, int>)(i => i), null!)
+            () => new TestExtractorWithTimer(i => i, null!)
         );
 
         Assert.Equal("timer", ex.ParamName);
@@ -785,7 +785,7 @@ public void Constructor_with_indexed_factory_count_and_timer_when_count_is_negat
         using var timer = new ManualProgressTimer();
         var ex = Assert.Throws<ArgumentOutOfRangeException>
         (
-            () => new TestExtractorWithTimer((Func<int, int>)(i => i), -1, timer)
+            () => new TestExtractorWithTimer(i => i, -1, timer)
         );
 
         Assert.Equal("count", ex.ParamName);
@@ -798,7 +798,7 @@ public void Constructor_with_indexed_factory_count_and_timer_when_timer_is_null_
     {
         var ex = Assert.Throws<ArgumentNullException>
         (
-            () => new TestExtractorWithTimer((Func<int, int>)(i => i), 3, null!)
+            () => new TestExtractorWithTimer(i => i, 3, null!)
         );
 
         Assert.Equal("timer", ex.ParamName);
diff --git a/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/ProgressAssertTests.cs b/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/ProgressAssertTests.cs
index 0a8ea451..6a60ea5d 100644
--- a/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/ProgressAssertTests.cs
+++ b/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/ProgressAssertTests.cs
@@ -261,7 +261,7 @@ public void FinalReportSatisfies_when_predicate_null_throws_ArgumentNullExceptio
         var capture = new ProgressCapture<int>();
 
         Assert.Throws<ArgumentNullException>(() =>
-            ProgressAssert.FinalReportSatisfies<int>(capture, null!));
+            ProgressAssert.FinalReportSatisfies(capture, null!));
     }
 
 
@@ -331,7 +331,7 @@ public void AllReportsSatisfy_when_predicate_null_throws_ArgumentNullException()
         var capture = new ProgressCapture<int>();
 
         Assert.Throws<ArgumentNullException>(() =>
-            ProgressAssert.AllReportsSatisfy<int>(capture, null!));
+            ProgressAssert.AllReportsSatisfy(capture, null!));
     }
 
 
diff --git a/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/RetryingExtractorRetryContractTests.cs b/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/RetryingExtractorRetryContractTests.cs
index 68a33c94..1011dec3 100644
--- a/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/RetryingExtractorRetryContractTests.cs
+++ b/tests/Wolfgang.Etl.TestKit.Xunit.Tests.Unit/RetryingExtractorRetryContractTests.cs
@@ -25,7 +25,7 @@ protected override Task<RetryOutcome> RunWithPermanentFaultAsync(int maxAttempts
     private static async Task<RetryOutcome> DriveAsync(RetryingExtractor<int> sut)
     {
         var itemCount = 0;
-        var succeeded = false;
+        bool succeeded;
 
         try
         {