Fix CA1062 warnings (#2219)

Fix CA1062 warnings for `NoOpPolicy`.

Author: Zombach

src/Polly/NoOp/NoOpPolicy.cs

@@ -4,7 +4,6 @@ namespace Polly.NoOp;
 /// <summary>
 /// A no op policy that can be applied to delegates.
 /// </summary>
-#pragma warning disable CA1062 // Validate arguments of public methods
 public class NoOpPolicy : Policy, INoOpPolicy
 {
     internal NoOpPolicy()
@@ -13,8 +12,15 @@ internal NoOpPolicy()
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        NoOpEngine.Implementation(action, context, 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 NoOpEngine.Implementation(action, context, cancellationToken);
+    }
 }
 
 /// <summary>
@@ -29,6 +35,13 @@ internal NoOpPolicy()
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        NoOpEngine.Implementation(action, context, cancellationToken);
+    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return NoOpEngine.Implementation(action, context, cancellationToken);
+    }
 }

test/Polly.Specs/NoOp/NoOpSpecs.cs

@@ -2,6 +2,25 @@
 
 public class NoOpSpecs
 {
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+
+        var instance = Activator.CreateInstance(typeof(NoOpPolicy), true)!;
+        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.WithInnerException<ArgumentNullException>("action");
+    }
+
     [Fact]
     public void Should_execute_user_delegate()
     {

test/Polly.Specs/NoOp/NoOpTResultSpecs.cs

@@ -2,6 +2,23 @@
 
 public class NoOpTResultSpecs
 {
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+
+        var instance = Activator.CreateInstance(typeof(NoOpPolicy<EmptyStruct>), true)!;
+        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.WithInnerException<ArgumentNullException>("action");
+    }
+
     [Fact]
     public void Should_execute_user_delegate()
     {