Fix warning CA1062#DefaultCacheKeyStrategy

src/Polly/Caching/DefaultCacheKeyStrategy.cs

@@ -4,16 +4,22 @@ namespace Polly.Caching;
 /// <summary>
 /// The default cache key strategy for <see cref="CachePolicy"/>.  Returns the property <see cref="Context.OperationKey"/>.
 /// </summary>
-#pragma warning disable CA1062 // Validate arguments of public methods
 public class DefaultCacheKeyStrategy : ICacheKeyStrategy
 {
     /// <summary>
     /// Gets the cache key from the given execution context.
     /// </summary>
     /// <param name="context">The execution context.</param>
     /// <returns>The cache key.</returns>
-    public string GetCacheKey(Context context) =>
-        context.OperationKey;
+    public string GetCacheKey(Context context)
+    {
+        if (context is null)
+        {
+            throw new ArgumentNullException(nameof(context));
+        }
+
+        return context.OperationKey;
+    }
 
     /// <summary>
     /// Gets an instance of the <see cref="DefaultCacheKeyStrategy"/>.

test/Polly.Specs/Caching/DefaultCacheKeyStrategySpecs.cs

@@ -2,6 +2,14 @@
 
 public class DefaultCacheKeyStrategySpecs
 {
+    [Fact]
+    public void Should_throw_when_context_is_null()
+    {
+        Context context = null!;
+        Action action = () => DefaultCacheKeyStrategy.Instance.GetCacheKey(context);
+        action.Should().Throw<ArgumentNullException>().And.ParamName.Should().Be("context");
+    }
+
     [Fact]
     public void Should_return_Context_OperationKey_as_cache_key()
     {