Handling null and empty setting name parameter in DefaultNameResolver

src/Microsoft.Azure.WebJobs.Host/DefaultNameResolver.cs

@@ -16,7 +16,7 @@ public class DefaultNameResolver : INameResolver
 
         public DefaultNameResolver(IConfiguration configuration)
         {
-            _configuration = configuration;
+            _configuration = configuration ?? throw new System.ArgumentNullException(nameof(configuration));
         }
 
         /// <summary>
@@ -26,6 +26,11 @@ public DefaultNameResolver(IConfiguration configuration)
         /// <returns>The token value from App Settings or environment variables. If the token is not found, null is returned.</returns>
         public virtual string Resolve(string name)
         {
+            if (string.IsNullOrEmpty(name))
+            {
+                return null;
+            }
+
             return _configuration[name];
         }
     }

test/Microsoft.Azure.WebJobs.Host.UnitTests/DefaultNameResolverTests.cs

@@ -0,0 +1,29 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using Microsoft.Extensions.Configuration;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace Microsoft.Azure.WebJobs.Host.UnitTests
+{
+    public class DefaultNameResolverTests
+    {
+        [Fact]
+        public void Resolve_WithNullOrEmptyNameParameter_ReturnsNull()
+        {
+            var configuration = new ConfigurationBuilder().Build();
+            var resolver = new DefaultNameResolver(configuration);
+
+            // Assert we null returns null
+            string result = resolver.Resolve(null);
+            Assert.Null(result);
+
+            // Assert empty returns null
+            result = resolver.Resolve(string.Empty);
+            Assert.Null(result);
+        }
+    }
+}