fix: chunkwriter hangs on cancel (#239)

* fix: chunkwriter hangs on cancel

* fix: chunkwriter hangs on cancel

Co-authored-by: David Gustafson <davigust@github.com>

azblob/chunkwriting_test.go

@@ -40,6 +40,8 @@ func newFakeBlockWriter() *fakeBlockWriter {
 func (f *fakeBlockWriter) StageBlock(ctx context.Context, blockID string, r io.ReadSeeker, cond LeaseAccessConditions, md5 []byte, cpk ClientProvidedKeyOptions) (*BlockBlobStageBlockResponse, error) {
 	n := atomic.AddInt32(&f.block, 1)
 	if n == f.errOnBlock {
+		// simulate activity
+		time.Sleep(100 * time.Millisecond)
 		return nil, io.ErrNoProgress
 	}
 
@@ -220,6 +222,13 @@ func TestCopyFromReader(t *testing.T) {
 			ctx:      context.Background(),
 			fileSize: _1MiB + 500*1024,
 		},
+		{
+			desc:      "Send file(12 MiB) with default UploadStreamToBlockBlobOptions and a write error",
+			ctx:       context.Background(),
+			fileSize:  12 * _1MiB,
+			uploadErr: true,
+			err:       true,
+		},
 		{
 			desc:     "Send file(1.5 MiB) with 2 writers",
 			ctx:      context.Background(),

azblob/url_blob.go

@@ -314,7 +314,7 @@ func (b BlobURL) StartCopyFromURL(ctx context.Context, source url.URL, metadata
 		nil,
 		// immutability policy
 		nil, BlobImmutabilityPolicyModeNone, nil,
-		)
+	)
 }
 
 // AbortCopyFromURL stops a pending copy that was previously started and leaves a destination blob with 0 length and metadata.