Show a pretty progressbar when uploading and downloading an image.

Add a new module that contain generic wrapper for file and iterator, which
are used to wrap image to upload and the request body iterator in upload and
download cases repectively, to show and advance a pretty progress bar when this
laters are consumed, The progress bar is triggered by adding a --progress command
line argument to commands: image-create, image-download or image-update.

Change-Id: I2ba42fd0c58f4fa087adb568ec3f08246cae3759
bug fix: LP#1112309
blueprint: progressbar-when-uploading

tests/test_http.py

@@ -13,6 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import errno
 import httplib
 import socket
 import StringIO
@@ -241,8 +242,42 @@ class TestHostResolutionError(testtools.TestCase):
 
 
 class TestResponseBodyIterator(testtools.TestCase):
+
     def test_iter_default_chunk_size_64k(self):
         resp = utils.FakeResponse({}, StringIO.StringIO('X' * 98304))
         iterator = http.ResponseBodyIterator(resp)
         chunks = list(iterator)
         self.assertEqual(chunks, ['X' * 65536, 'X' * 32768])
+
+    def test_integrity_check_with_correct_checksum(self):
+        resp = utils.FakeResponse({}, StringIO.StringIO('CCC'))
+        body = http.ResponseBodyIterator(resp)
+        body.set_checksum('defb99e69a9f1f6e06f15006b1f166ae')
+        list(body)
+
+    def test_integrity_check_with_wrong_checksum(self):
+        resp = utils.FakeResponse({}, StringIO.StringIO('BB'))
+        body = http.ResponseBodyIterator(resp)
+        body.set_checksum('wrong')
+        try:
+            list(body)
+            self.fail('integrity checked passed with wrong checksum')
+        except IOError as e:
+            self.assertEqual(errno.EPIPE, e.errno)
+
+    def test_set_checksum_in_consumed_iterator(self):
+        resp = utils.FakeResponse({}, StringIO.StringIO('CCC'))
+        body = http.ResponseBodyIterator(resp)
+        list(body)
+        # Setting checksum for an already consumed iterator should raise an
+        # AttributeError.
+        self.assertRaises(
+            AttributeError, body.set_checksum,
+            'defb99e69a9f1f6e06f15006b1f166ae')
+
+    def test_body_size(self):
+        size = 1000000007
+        resp = utils.FakeResponse(
+            {'content-length': str(size)}, StringIO.StringIO('BB'))
+        body = http.ResponseBodyIterator(resp)
+        self.assertEqual(len(body), size)