[Storage] Make Specialized Blob Clients retrieval mockable.

sdk/storage/Azure.Storage.Blobs/src/AppendBlobClient.cs

@@ -1589,23 +1589,7 @@ public static AppendBlobClient GetAppendBlobClient(
             this BlobContainerClient client,
             string blobName)
         {
-            if (client.ClientSideEncryption != default)
-            {
-                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(AppendBlobClient));
-            }
-
-            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(client.Uri)
-            {
-                BlobName = blobName
-            };
-
-            return new AppendBlobClient(
-                blobUriBuilder.ToUri(),
-                client.Pipeline,
-                client.Version,
-                client.ClientDiagnostics,
-                client.CustomerProvidedKey,
-                client.EncryptionScope);
+            return client.GetAppendBlobClientInternal(blobName);
         }
     }
 }

sdk/storage/Azure.Storage.Blobs/src/BlobContainerClient.cs

@@ -405,6 +405,98 @@ public virtual BlobClient GetBlobClient(string blobName)
                 EncryptionScope);
         }
 
+        /// <summary>
+        /// Create a new <see cref="BlockBlobClient"/> object by
+        /// concatenating <paramref name="blobName"/> to
+        /// the end of the <see cref="Uri"/>. The new
+        /// <see cref="BlockBlobClient"/>
+        /// uses the same request policy pipeline as the
+        /// <see cref="BlobContainerClient"/>.
+        /// </summary>
+        /// <param name="blobName">The name of the block blob.</param>
+        /// <returns>A new <see cref="BlockBlobClient"/> instance.</returns>
+        protected internal virtual BlockBlobClient GetBlockBlobClientInternal(string blobName)
+        {
+            if (ClientSideEncryption != default)
+            {
+                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(BlockBlobClient));
+            }
+
+            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(Uri)
+            {
+                BlobName = blobName
+            };
+
+            return new BlockBlobClient(
+                blobUriBuilder.ToUri(),
+                Pipeline,
+                Version,
+                ClientDiagnostics,
+                CustomerProvidedKey,
+                EncryptionScope);
+        }
+
+        /// <summary>
+        /// Create a new <see cref="AppendBlobClient"/> object by
+        /// concatenating <paramref name="blobName"/> to
+        /// the end of the <see cref="BlobContainerClient.Uri"/>. The new
+        /// <see cref="AppendBlobClient"/>
+        /// uses the same request policy pipeline as the
+        /// <see cref="BlobContainerClient"/>.
+        /// </summary>
+        /// <param name="blobName">The name of the append blob.</param>
+        /// <returns>A new <see cref="AppendBlobClient"/> instance.</returns>
+        protected internal virtual AppendBlobClient GetAppendBlobClientInternal(string blobName)
+        {
+            if (ClientSideEncryption != default)
+            {
+                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(AppendBlobClient));
+            }
+
+            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(Uri)
+            {
+                BlobName = blobName
+            };
+
+            return new AppendBlobClient(
+                blobUriBuilder.ToUri(),
+                Pipeline,
+                Version,
+                ClientDiagnostics,
+                CustomerProvidedKey,
+                EncryptionScope);
+        }
+
+        /// <summary>
+        /// Create a new <see cref="PageBlobClient"/> object by
+        /// concatenating <paramref name="blobName"/> to
+        /// the end of the <see cref="BlobContainerClient.Uri"/>. The new
+        /// <see cref="PageBlobClient"/>
+        /// uses the same request policy pipeline as the
+        /// <see cref="BlobContainerClient"/>.
+        /// </summary>
+        /// <param name="blobName">The name of the page blob.</param>
+        /// <returns>A new <see cref="PageBlobClient"/> instance.</returns>
+        protected internal virtual PageBlobClient GetPageBlobClientInternal(string blobName)
+        {
+            if (ClientSideEncryption != default)
+            {
+                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(PageBlobClient));
+            }
+
+            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(Uri)
+            {
+                BlobName = blobName
+            };
+
+            return new PageBlobClient(
+                blobUriBuilder.ToUri(),
+                Pipeline,
+                Version,
+                ClientDiagnostics,
+                CustomerProvidedKey,
+                EncryptionScope);
+        }
 
         /// <summary>
         /// Sets the various name fields if they are currently null.

sdk/storage/Azure.Storage.Blobs/src/BlockBlobClient.cs

@@ -2232,23 +2232,7 @@ public static BlockBlobClient GetBlockBlobClient(
             this BlobContainerClient client,
             string blobName)
         {
-            if (client.ClientSideEncryption != default)
-            {
-                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(BlockBlobClient));
-            }
-
-            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(client.Uri)
-            {
-                BlobName = blobName
-            };
-
-            return new BlockBlobClient(
-                blobUriBuilder.ToUri(),
-                client.Pipeline,
-                client.Version,
-                client.ClientDiagnostics,
-                client.CustomerProvidedKey,
-                client.EncryptionScope);
+            return client.GetBlockBlobClientInternal(blobName);
         }
     }
 }

sdk/storage/Azure.Storage.Blobs/src/PageBlobClient.cs

@@ -3114,23 +3114,7 @@ public static PageBlobClient GetPageBlobClient(
             this BlobContainerClient client,
             string blobName)
         {
-            if (client.ClientSideEncryption != default)
-            {
-                throw Errors.ClientSideEncryption.TypeNotSupported(typeof(PageBlobClient));
-            }
-
-            BlobUriBuilder blobUriBuilder = new BlobUriBuilder(client.Uri)
-            {
-                BlobName = blobName
-            };
-
-            return new PageBlobClient(
-                blobUriBuilder.ToUri(),
-                client.Pipeline,
-                client.Version,
-                client.ClientDiagnostics,
-                client.CustomerProvidedKey,
-                client.EncryptionScope);
+            return client.GetPageBlobClientInternal(blobName);
         }
     }
 }

sdk/storage/Azure.Storage.Blobs/tests/ContainerClientTests.cs

@@ -5,7 +5,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Reflection.Metadata;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -17,6 +16,8 @@
 using Azure.Storage.Sas;
 using Azure.Storage.Test;
 using Azure.Storage.Test.Shared;
+using Moq;
+using Moq.Protected;
 using NUnit.Framework;
 
 namespace Azure.Storage.Blobs.Test
@@ -2512,6 +2513,33 @@ public async Task GetBlobClients_SpecialCharacters(string blobName)
             Assert.AreEqual(blobName, pageBlobClientFromConnectionString.Name);
         }
 
+        [Test]
+        public void CanMockBlobClientsRetrieval()
+        {
+            // Arrange
+            string blobName = "test";
+            Mock<BlobContainerClient> containerClientMock = new Mock<BlobContainerClient>();
+            Mock<BlockBlobClient> blockBlobClientMock = new Mock<BlockBlobClient>();
+            Mock<AppendBlobClient> appendBlobClientMock = new Mock<AppendBlobClient>();
+            Mock<PageBlobClient> pageBlobClientMock = new Mock<PageBlobClient>();
+            containerClientMock.Protected().Setup<BlockBlobClient>("GetBlockBlobClientInternal", blobName).Returns(blockBlobClientMock.Object);
+            containerClientMock.Protected().Setup<AppendBlobClient>("GetAppendBlobClientInternal", blobName).Returns(appendBlobClientMock.Object);
+            containerClientMock.Protected().Setup<PageBlobClient>("GetPageBlobClientInternal", blobName).Returns(pageBlobClientMock.Object);
+
+            // Act
+            var blockBlobClient = containerClientMock.Object.GetBlockBlobClient(blobName);
+            var appendBlobClient = containerClientMock.Object.GetAppendBlobClient(blobName);
+            var pageBlobClient = containerClientMock.Object.GetPageBlobClient(blobName);
+
+            // Assert
+            Assert.IsNotNull(blockBlobClient);
+            Assert.AreSame(blockBlobClientMock.Object, blockBlobClient);
+            Assert.IsNotNull(appendBlobClient);
+            Assert.AreSame(appendBlobClientMock.Object, appendBlobClient);
+            Assert.IsNotNull(pageBlobClient);
+            Assert.AreSame(pageBlobClientMock.Object, pageBlobClient);
+        }
+
         #region Secondary Storage
         [Test]
         public async Task ListContainersSegmentAsync_SecondaryStorageFirstRetrySuccessful()