Adding optional stream argument to DownloadBase.

google/resumable_media/_download.py

@@ -37,6 +37,8 @@ class DownloadBase(object):
 
     Args:
         media_url (str): The URL containing the media to be downloaded.
+        stream (IO[bytes]): A write-able stream (i.e. file-like object) that
+            the downloaded resource can be written to.
         start (int): The first byte in a range to be downloaded.
         end (int): The last byte in a range to be downloaded.
         headers (Optional[Mapping[str, str]]): Extra headers that should
@@ -48,8 +50,10 @@ class DownloadBase(object):
         end (Optional[int]): The last byte in a range to be downloaded.
     """
 
-    def __init__(self, media_url, start=None, end=None, headers=None):
+    def __init__(self, media_url, stream=None,
+                 start=None, end=None, headers=None):
         self.media_url = media_url
+        self._stream = stream
         self.start = start
         self.end = end
         if headers is None:
@@ -109,6 +113,8 @@ class Download(DownloadBase):
 
     Args:
         media_url (str): The URL containing the media to be downloaded.
+        stream (IO[bytes]): A write-able stream (i.e. file-like object) that
+            the downloaded resource can be written to.
         start (int): The first byte in a range to be downloaded. If not
             provided, but ``end`` is provided, will download from the
             beginning to ``end`` of the media.
@@ -166,6 +172,9 @@ def _process_response(self, response):
     def consume(self, transport):
         """Consume the resource to be downloaded.
 
+        If a ``stream`` is attached to this download, then the downloaded
+        resource will be written to the stream.
+
         Args:
             transport (object): An object which can make authenticated
                 requests.
@@ -211,9 +220,8 @@ def __init__(self, media_url, chunk_size, stream,
                 u'On a chunked download the starting '
                 u'value cannot be negative.')
         super(ChunkedDownload, self).__init__(
-            media_url, start=start, end=end, headers=headers)
+            media_url, stream=stream, start=start, end=end, headers=headers)
         self.chunk_size = chunk_size
-        self._stream = stream
         self._bytes_downloaded = 0
         self._total_bytes = None
         self._invalid = False

google/resumable_media/requests/download.py

@@ -28,6 +28,8 @@ class Download(_helpers.RequestsMixin, _download.Download):
 
     Args:
         media_url (str): The URL containing the media to be downloaded.
+        stream (IO[bytes]): A write-able stream (i.e. file-like object) that
+            the downloaded resource can be written to.
         start (int): The first byte in a range to be downloaded. If not
             provided, but ``end`` is provided, will download from the
             beginning to ``end`` of the media.

tests/unit/test__download.py

@@ -32,6 +32,7 @@ class TestDownloadBase(object):
     def test_constructor_defaults(self):
         download = _download.DownloadBase(EXAMPLE_URL)
         assert download.media_url == EXAMPLE_URL
+        assert download._stream is None
         assert download.start is None
         assert download.end is None
         assert download._headers == {}
@@ -43,8 +44,10 @@ def test_constructor_explicit(self):
         end = 10001
         headers = {u'foof': u'barf'}
         download = _download.DownloadBase(
-            EXAMPLE_URL, start=start, end=end, headers=headers)
+            EXAMPLE_URL, stream=mock.sentinel.stream,
+            start=start, end=end, headers=headers)
         assert download.media_url == EXAMPLE_URL
+        assert download._stream is mock.sentinel.stream
         assert download.start == start
         assert download.end == end
         assert download._headers is headers