Fix CA1062 warnings (#2232)

Fix CA1062 warnings for `FallbackPolicy`.
App-vNext · Jul 23, 2024 · ff3b1f4 · ff3b1f4
1 parent f054ef7
commit ff3b1f4
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Showing 2 changed files with 36 additions and 3 deletions.
diff --git a/src/Polly/Fallback/FallbackPolicy.cs b/src/Polly/Fallback/FallbackPolicy.cs
@@ -4,7 +4,6 @@ namespace Polly.Fallback;
 /// <summary>
 /// A fallback policy that can be applied to delegates.
 /// </summary>
-#pragma warning disable CA1062 // Validate arguments of public methods
 public class FallbackPolicy : Policy, IFallbackPolicy
 {
     private readonly Action<Exception, Context> _onFallback;
@@ -69,13 +68,20 @@ internal FallbackPolicy(
 
     /// <inheritdoc/>
     [DebuggerStepThrough]
-    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken) =>
-        FallbackEngine.Implementation(
+    protected override TResult Implementation(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
+    {
+        if (action is null)
+        {
+            throw new ArgumentNullException(nameof(action));
+        }
+
+        return FallbackEngine.Implementation(
             action,
             context,
             ExceptionPredicates,
             ResultPredicates,
             _onFallback,
             _fallbackAction,
             cancellationToken);
+    }
 }
diff --git a/test/Polly.Specs/Fallback/FallbackTResultSpecs.cs b/test/Polly.Specs/Fallback/FallbackTResultSpecs.cs
@@ -6,6 +6,33 @@ public class FallbackTResultSpecs
 {
     #region Configuration guard condition tests
 
+    [Fact]
+    public void Should_throw_when_action_is_null()
+    {
+        var flags = BindingFlags.NonPublic | BindingFlags.Instance;
+        Func<Context, CancellationToken, EmptyStruct> action = null!;
+        PolicyBuilder<EmptyStruct> policyBuilder = new PolicyBuilder<EmptyStruct>(exception => exception);
+        Action<DelegateResult<EmptyStruct>, Context> onFallback = (_, _) => { };
+        Func<DelegateResult<EmptyStruct>, Context, CancellationToken, EmptyStruct> fallbackAction = (_, _, _) => EmptyStruct.Instance;
+
+        var instance = Activator.CreateInstance(
+            typeof(FallbackPolicy<EmptyStruct>),
+            flags,
+            null,
+            [policyBuilder, onFallback, fallbackAction],
+            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_fallback_action_is_null()
     {