Fix URI -> blob name conversion in 'Client download_blob_to_file'. (#…

…8440)

storage/google/cloud/storage/client.py

@@ -390,7 +390,7 @@ def download_blob_to_file(self, blob_or_uri, file_obj, start=None, end=None):
             if scheme != "gs":
                 raise ValueError("URI scheme must be gs")
             bucket = Bucket(self, name=netloc)
-            blob_or_uri = Blob(path, bucket)
+            blob_or_uri = Blob(path[1:], bucket)
 
             blob_or_uri.download_to_file(file_obj, client=self, start=start, end=end)
 

storage/tests/system.py

@@ -552,6 +552,23 @@ def test_copy_existing_file(self):
         copied_contents = new_blob.download_as_string()
         self.assertEqual(base_contents, copied_contents)
 
+    def test_download_blob_w_uri(self):
+        blob = self.bucket.blob("MyBuffer")
+        file_contents = b"Hello World"
+        blob.upload_from_string(file_contents)
+        self.case_blobs_to_delete.append(blob)
+
+        temp_filename = tempfile.mktemp()
+        with open(temp_filename, "wb") as file_obj:
+            Config.CLIENT.download_blob_to_file(
+                "gs://" + self.bucket.name + "/MyBuffer", file_obj
+            )
+
+        with open(temp_filename, "rb") as file_obj:
+            stored_contents = file_obj.read()
+
+        self.assertEqual(file_contents, stored_contents)
+
 
 class TestUnicode(unittest.TestCase):
     @unittest.skipIf(RUNNING_IN_VPCSC, "Test is not VPCSC compatible.")