Fixed bug where Listing Blobs with BlobTraits.Metadata would return B…

sdk/storage/Azure.Storage.Blobs/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 12.7.0-preview.1 (Unreleased)
 - Fixed bug where Stream returned from AppendBlobClient.OpenWrite(), BlockBlobClient.OpenWrite() and PageBlobClient.OpenWrite() did not flush while disposing preventing compatibility with using keyword.
+- Fixed bug where Listing Blobs with BlobTraits.Metadata would return BlobItems with null metadata instead of an empty dictionary if no metadata was present.
 
 ## 12.6.0 (2020-08-31)
 - Fixed bug where BlobClient.Upload(), BlockBlobClient.Upload(), AppendBlobClient.AppendBlock(), and PageBlobClient.UploadPages() would deadlock if the content stream's position was not 0.

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

@@ -59,7 +59,7 @@ internal static BlobItem ToBlobItem(this BlobItemInternal blobItemInternal)
                 IsLatestVersion = blobItemInternal.IsCurrentVersion,
                 Metadata = blobItemInternal.Metadata?.Count > 0
                     ? blobItemInternal.Metadata
-                    : null,
+                    : new Dictionary<string, string>(),
                 Tags = blobItemInternal.BlobTags.ToTagDictionary(),
                 ObjectReplicationSourceProperties = blobItemInternal.ObjectReplicationMetadata?.Count > 0
                     ? ParseObjectReplicationMetadata(blobItemInternal.ObjectReplicationMetadata)

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

@@ -1779,7 +1779,7 @@ public async Task ListBlobsFlatSegmentAsync_MaxResults()
 
             // Assert
             Assert.AreEqual(2, page.Values.Count);
-            Assert.IsTrue(page.Values.All(b => b.Metadata == null));
+            Assert.IsTrue(page.Values.All(b => b.Metadata.Count == 0));
         }
 
         [Test]
@@ -2107,6 +2107,23 @@ public async Task ListBlobsHierarchySegmentAsync_Metadata()
             AssertDictionaryEquality(metadata, item.Blob.Metadata);
         }
 
+        [Test]
+        public async Task ListBlobsHierarchySegmentAsync_Metadata_NoMetadata()
+        {
+            await using DisposingContainer test = await GetTestContainerAsync();
+
+            // Arrange
+            AppendBlobClient blob = InstrumentClient(test.Container.GetAppendBlobClient(GetNewBlobName()));
+            await blob.CreateAsync();
+
+            // Act
+            BlobHierarchyItem item = await test.Container.GetBlobsByHierarchyAsync(traits: BlobTraits.Metadata).FirstAsync();
+
+            // Assert
+            Assert.IsNotNull(item.Blob.Metadata);
+            Assert.AreEqual(0, item.Blob.Metadata.Count);
+        }
+
         [Test]
         [ServiceVersion(Min = BlobClientOptions.ServiceVersion.V2019_07_07)]
         public async Task ListBlobsHierarchySegmentAsync_EncryptionScope()