Fix CA1062 warnings (#2227)

Fix warnings for `TimeoutPolicy`.

Author: Zombach

src/Polly/Timeout/TimeoutPolicy.cs

@@ -3,7 +3,6 @@
 /// <summary>
 /// A timeout policy which can be applied to delegates.
 /// </summary>
-#pragma warning disable CA1062 // Validate arguments of public methods
 public class TimeoutPolicy : Policy, ITimeoutPolicy
 {
     private readonly TimeoutStrategy _timeoutStrategy;
@@ -22,14 +21,21 @@ internal TimeoutPolicy(
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        TimeoutEngine.Implementation(
+    protected override TResult Implementation<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return TimeoutEngine.Implementation(
             action,
             context,
             _timeoutProvider,
             _timeoutStrategy,
             _onTimeout,
             cancellationToken);
+    }
 }
 
 /// <summary>
@@ -53,12 +59,19 @@ internal TimeoutPolicy(
     }
 
     /// <inheritdoc/>
-    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        TimeoutEngine.Implementation(
+    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return TimeoutEngine.Implementation(
             action,
             context,
             _timeoutProvider,
             _timeoutStrategy,
             _onTimeout,
             cancellationToken);
+    }
 }

test/Polly.Specs/Timeout/TimeoutSpecs.cs

@@ -5,6 +5,34 @@ public class TimeoutSpecs : TimeoutSpecsBase
 {
     #region Configuration
 
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+        Func<Context, TimeSpan> timeoutProvider = (_) => TimeSpan.Zero;
+        TimeoutStrategy timeoutStrategy = TimeoutStrategy.Optimistic;
+        Action<Context, TimeSpan, Task, Exception> onTimeout = (_, _, _, _) => { };
+
+        var instance = Activator.CreateInstance(
+            typeof(TimeoutPolicy),
+            flags,
+            null,
+            [timeoutProvider, timeoutStrategy, onTimeout],
+            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_timeout_is_zero_by_timespan()
     {

test/Polly.Specs/Timeout/TimeoutTResultSpecs.cs

@@ -5,6 +5,33 @@ public class TimeoutTResultSpecs : TimeoutSpecsBase
 {
     #region Configuration
 
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+        Func<Context, TimeSpan> timeoutProvider = (_) => TimeSpan.Zero;
+        TimeoutStrategy timeoutStrategy = TimeoutStrategy.Optimistic;
+        Action<Context, TimeSpan, Task, Exception> onTimeout = (_, _, _, _) => { };
+
+        var instance = Activator.CreateInstance(
+            typeof(TimeoutPolicy<EmptyStruct>),
+            flags,
+            null,
+            [timeoutProvider, timeoutStrategy, onTimeout],
+            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_timeout_is_zero_by_timespan()
     {