add some test cases around getCachedClient (#30383)

Author: ArcturusZhang

sdk/resourcemanager/Azure.ResourceManager/tests/Scenario/ArmResourceTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Threading.Tasks;
+using Azure.Core;
 using Azure.Core.TestFramework;
 using Azure.ResourceManager.Resources;
 using NUnit.Framework;
@@ -37,5 +38,46 @@ public async Task GetCachedClient()
             Assert.IsTrue(ReferenceEquals(obj1, obj2));
             Assert.IsTrue(ReferenceEquals(obj1.Client, obj2.Client));
         }
+
+        private class TestObjectWithClosure
+        {
+            public ArmClient Client { get; }
+            public ResourceIdentifier Id { get; }
+
+            public TestObjectWithClosure(ArmClient client, ResourceIdentifier id)
+            {
+                Client = client;
+                Id = id;
+            }
+        }
+
+        private class ArmClientExtensionClient : ArmResource
+        {
+            public ArmClientExtensionClient(ArmClient client, ResourceIdentifier id) : base(client, id)
+            {
+            }
+
+            public TestObjectWithClosure GetTestObject()
+            {
+                return GetCachedClient(Client => new TestObjectWithClosure(Client, Id));
+            }
+        }
+
+        [RecordedTest]
+        public async Task GetCachedClientWithClosure()
+        {
+            SubscriptionResource subscription = await Client.GetDefaultSubscriptionAsync();
+            ResourceIdentifier scope1 = new(subscription.Id + "/resourceGroups/rg1");
+            var extensionClient1 = new ArmClientExtensionClient(Client, scope1);
+            var obj1 = extensionClient1.GetTestObject();
+            var obj2 = extensionClient1.GetTestObject();
+            Assert.IsTrue(ReferenceEquals(obj1, obj2));
+            Assert.IsTrue(ReferenceEquals(obj1.Client, obj2.Client));
+            ResourceIdentifier scope2 = new(subscription.Id + "/resourceGroups/rg2");
+            var extensionClient2 = new ArmClientExtensionClient(Client, scope2);
+            var obj3 = extensionClient2.GetTestObject();
+            Assert.IsFalse(ReferenceEquals(obj1, obj3));
+            Assert.IsTrue(ReferenceEquals(obj1.Client, obj3.Client));
+        }
     }
 }