Fix warning CA1062#BulkheadPolicy

src/Polly/Bulkhead/BulkheadPolicy.cs

@@ -4,7 +4,6 @@ namespace Polly.Bulkhead;
 /// <summary>
 /// A bulkhead-isolation policy which can be applied to delegates.
 /// </summary>
-#pragma warning disable CA1062 // Validate arguments of public methods
 public class BulkheadPolicy : Policy, IBulkheadPolicy
 {
     private readonly SemaphoreSlim _maxParallelizationSemaphore;
@@ -25,8 +24,21 @@ internal BulkheadPolicy(
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        BulkheadEngine.Implementation(action, context, _onBulkheadRejected, _maxParallelizationSemaphore, _maxQueuedActionsSemaphore, cancellationToken);
+    protected override TResult Implementation<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return BulkheadEngine.Implementation(
+            action,
+            context,
+            _onBulkheadRejected,
+            _maxParallelizationSemaphore,
+            _maxQueuedActionsSemaphore,
+            cancellationToken);
+    }
 
     /// <summary>
     /// Gets the number of slots currently available for executing actions through the bulkhead.
@@ -73,8 +85,20 @@ internal BulkheadPolicy(
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        BulkheadEngine.Implementation(action, context, _onBulkheadRejected, _maxParallelizationSemaphore, _maxQueuedActionsSemaphore, cancellationToken);
+    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return BulkheadEngine.Implementation(
+            action,
+            context,
+            _onBulkheadRejected,
+            _maxParallelizationSemaphore,
+            _maxQueuedActionsSemaphore, cancellationToken);
+    }
 
     /// <summary>
     /// Gets the number of slots currently available for executing actions through the bulkhead.

test/Polly.Specs/Bulkhead/BulkheadSpecs.cs

@@ -10,6 +10,34 @@ public BulkheadSpecs(ITestOutputHelper testOutputHelper)
 
     #region Configuration
 
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+        var maxParallelization = 1;
+        var maxQueueingActions = 1;
+        Action<Context> onBulkheadRejected = _ => { };
+
+        var instance = Activator.CreateInstance(
+            typeof(BulkheadPolicy),
+            flags,
+            null,
+            [maxParallelization, maxQueueingActions, onBulkheadRejected],
+            null)!;
+        var instanceType = instance.GetType();
+        var methods = instanceType.GetMethods(flags);
+        var methodInfo = methods.First(method => method is { Name: "Implementation", ReturnType.Name: "TResult" });
+        var generic = methodInfo.MakeGenericMethod(typeof(EmptyStruct));
+
+        var func = () => generic.Invoke(instance, [action, new Context(), CancellationToken.None]);
+
+        var exceptionAssertions = func.Should().Throw<TargetInvocationException>();
+        exceptionAssertions.And.Message.Should().Be("Exception has been thrown by the target of an invocation.");
+        exceptionAssertions.And.InnerException.Should().BeOfType<ArgumentNullException>()
+            .Which.ParamName.Should().Be("action");
+    }
+
     [Fact]
     public void Should_throw_when_maxParallelization_less_or_equal_to_zero_and_no_maxQueuingActions()
     {

test/Polly.Specs/Bulkhead/BulkheadTResultSpecs.cs

@@ -10,6 +10,33 @@ public BulkheadTResultSpecs(ITestOutputHelper testOutputHelper)
 
     #region Configuration
 
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+        var maxParallelization = 1;
+        var maxQueueingActions = 1;
+        Action<Context> onBulkheadRejected = _ => { };
+
+        var instance = Activator.CreateInstance(
+            typeof(BulkheadPolicy<EmptyStruct>),
+            flags,
+            null,
+            [maxParallelization, maxQueueingActions, onBulkheadRejected],
+            null)!;
+        var instanceType = instance.GetType();
+        var methods = instanceType.GetMethods(flags);
+        var methodInfo = methods.First(method => method is { Name: "Implementation", ReturnType.Name: "EmptyStruct" });
+
+        var func = () => methodInfo.Invoke(instance, [action, new Context(), CancellationToken.None]);
+
+        var exceptionAssertions = func.Should().Throw<TargetInvocationException>();
+        exceptionAssertions.And.Message.Should().Be("Exception has been thrown by the target of an invocation.");
+        exceptionAssertions.And.InnerException.Should().BeOfType<ArgumentNullException>()
+            .Which.ParamName.Should().Be("action");
+    }
+
     [Fact]
     public void Should_throw_when_maxParallelization_less_or_equal_to_zero_and_no_maxQueuingActions()
     {