Utility to dump JSON to bytes.

src/allmydata/test/test_util.py

@@ -507,7 +507,6 @@ class JSONBytes(unittest.TestCase):
         self.assertEqual(json.loads(encoded), expected)
         self.assertEqual(jsonbytes.loads(encoded), expected)
 
-
     def test_encode_unicode(self):
         """BytesJSONEncoder encodes Unicode string as usual."""
         expected = {
@@ -515,3 +514,10 @@ class JSONBytes(unittest.TestCase):
         }
         encoded = jsonbytes.dumps(expected)
         self.assertEqual(json.loads(encoded), expected)
+
+    def test_dumps_bytes(self):
+        """jsonbytes.dumps_bytes always returns bytes."""
+        x = {u"def\N{SNOWMAN}\uFF00": 123}
+        encoded = jsonbytes.dumps_bytes(x)
+        self.assertIsInstance(encoded, bytes)
+        self.assertEqual(json.loads(encoded, encoding="utf-8"), x)

src/allmydata/util/jsonbytes.py

@@ -9,7 +9,7 @@ from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
 
-from future.utils import PY2
+from future.utils import PY2, PY3
 if PY2:
     from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401
 
@@ -51,6 +51,14 @@ def dumps(obj, *args, **kwargs):
     return json.dumps(obj, cls=BytesJSONEncoder, *args, **kwargs)
 
 
+def dumps_bytes(obj, *args, **kwargs):
+    """Encode to JSON, then encode as bytes."""
+    result = dumps(obj, *args, **kwargs)
+    if PY3:
+        result = result.encode("utf-8")
+    return result
+
+
 # To make this module drop-in compatible with json module:
 loads = json.loads