Moving MD5 hash method from regression to storage helpers.

May make sense to swap out for `hashlib.md5` (though they seem to
be equivalent).

In preparation for googleapis#547.

gcloud/storage/_helpers.py

@@ -17,6 +17,9 @@
 These are *not* part of the API.
 """
 
+from Crypto.Hash import MD5
+import base64
+
 
 class _PropertyMixin(object):
     """Abstract mixin for cloud storage classes with associated propertties.
@@ -187,3 +190,14 @@ def _setter(self, value):
         self._patch_properties({fieldname: value})
 
     return property(_getter, _setter)
+
+
+def _base64_md5hash(bytes_to_sign):
+    """Get MD5 hash of bytes (as base64).
+
+    :type bytes_to_sign: bytes
+    :param bytes_to_sign: Bytes used to compute an MD5 hash (as base64).
+    """
+    hash = MD5.new(data=bytes_to_sign)
+    digest_bytes = hash.digest()
+    return base64.b64encode(digest_bytes)

gcloud/storage/test__helpers.py

@@ -237,6 +237,35 @@ def _patch_properties(self, mapping):
         self.assertEqual(test._patched, {'solfege': 'Latido'})
 
 
+class Test__base64_md5hash(unittest2.TestCase):
+
+    def _callFUT(self, bytes_to_sign):
+        from gcloud.storage._helpers import _base64_md5hash
+        return _base64_md5hash(bytes_to_sign)
+
+    def test_it(self):
+        BYTES_TO_SIGN = b'FOO'
+        SIGNED_CONTENT = self._callFUT(BYTES_TO_SIGN)
+        self.assertEqual(SIGNED_CONTENT, b'kBiQqOnIz21aGlQrIp/r/w==')
+
+    def test_it_with_stubs(self):
+        from gcloud._testing import _Monkey
+        from gcloud.storage import _helpers as MUT
+
+        BASE64 = _Base64()
+        DIGEST_VAL = object()
+        BYTES_TO_SIGN = object()
+        MD5 = _MD5(DIGEST_VAL)
+
+        with _Monkey(MUT, base64=BASE64, MD5=MD5):
+            SIGNED_CONTENT = self._callFUT(BYTES_TO_SIGN)
+
+        self.assertTrue(SIGNED_CONTENT is DIGEST_VAL)
+        self.assertEqual(BASE64._called_b64encode, [DIGEST_VAL])
+        self.assertEqual(MD5._new_called, [BYTES_TO_SIGN])
+        self.assertEqual(MD5.hash_obj.num_digest_calls, 1)
+
+
 class _Connection(object):
 
     def __init__(self, *responses):
@@ -247,3 +276,34 @@ def api_request(self, **kw):
         self._requested.append(kw)
         response, self._responses = self._responses[0], self._responses[1:]
         return response
+
+
+class _MD5Hash(object):
+
+    def __init__(self, digest_val):
+        self.digest_val = digest_val
+        self.num_digest_calls = 0
+
+    def digest(self):
+        self.num_digest_calls += 1
+        return self.digest_val
+
+class _MD5(object):
+
+    def __init__(self, digest_val):
+        self.hash_obj = _MD5Hash(digest_val)
+        self._new_called = []
+
+    def new(self, data=None):
+        self._new_called.append(data)
+        return self.hash_obj
+
+
+class _Base64(object):
+
+    def __init__(self):
+        self._called_b64encode = []
+
+    def b64encode(self, value):
+        self._called_b64encode.append(value)
+        return value

regression/storage.py

@@ -12,15 +12,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from Crypto.Hash import MD5
-import base64
 import httplib2
 import tempfile
 import time
 import unittest2
 
 from gcloud import exceptions
 from gcloud import storage
+from gcloud.storage._helpers import _base64_md5hash
 from gcloud.storage import _implicit_environ
 
 
@@ -96,18 +95,12 @@ class TestStorageFiles(unittest2.TestCase):
         }
     }
 
-    @staticmethod
-    def _get_base64_md5hash(filename):
-        with open(filename, 'rb') as file_obj:
-            hash = MD5.new(data=file_obj.read())
-        digest_bytes = hash.digest()
-        return base64.b64encode(digest_bytes)
-
     @classmethod
     def setUpClass(cls):
         super(TestStorageFiles, cls).setUpClass()
         for file_data in cls.FILES.values():
-            file_data['hash'] = cls._get_base64_md5hash(file_data['path'])
+            with open(file_data['path'], 'rb') as file_obj:
+                file_data['hash'] = _base64_md5hash(file_obj.read())
         cls.bucket = SHARED_BUCKETS['test_bucket']
 
     def setUp(self):