Python3: Fix return type on CooperativeReader.read

CooperativeReader.read() should return bytes. A similar change was
merged in Glance.

Change-Id: Iee3b49235be2af64eac3933e41c7e44fc1a564f4
Closes-Bug: #1818915

3 files changed, 32 insertions, 1 deletions

diff --git a/glance_store/common/utils.py b/glance_store/common/utils.py
index 9bdb387..49acccb 100644
--- a/glance_store/common/utils.py
+++ b/glance_store/common/utils.py
@@ -135,7 +135,7 @@ class CooperativeReader(object):
         try:
             return next(self.iterator)
         except StopIteration:
-            return ''
+            return b''
 
     def __iter__(self):
         return cooperative_iter(self.fd.__iter__())
diff --git a/glance_store/tests/unit/common/__init__.py b/glance_store/tests/unit/common/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/glance_store/tests/unit/common/__init__.py
diff --git a/glance_store/tests/unit/common/test_utils.py b/glance_store/tests/unit/common/test_utils.py
new file mode 100644
index 0000000..71841c8
--- /dev/null
+++ b/glance_store/tests/unit/common/test_utils.py
@@ -0,0 +1,31 @@
+# Copyright 2018 RedHat Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import tempfile
+
+from oslotest import base
+
+from glance_store.common import utils
+
+
+class TestUtils(base.BaseTestCase):
+    def test_cooperative_reader_returns_bytes(self):
+        with tempfile.TemporaryFile() as fd:
+            reader = utils.CooperativeReader(fd)
+            # Make sure CooperativeReader does not use cooperative_read instead
+            # of its own read method.
+            reader.read = utils.CooperativeReader.read
+            out = reader.read(reader)
+            self.assertEqual(out, b'')