Use unicode chars instead of escape sequences in json encoder

Fixes #87

Author: mdsakalu

awslambdaric/lambda_runtime_marshaller.py

@@ -12,9 +12,10 @@
 
 # simplejson's Decimal encoding allows '-NaN' as an output, which is a parse error for json.loads
 # to get the good parts of Decimal support, we'll special-case NaN decimals and otherwise duplicate the encoding for decimals the same way simplejson does
+# We also set 'ensure_ascii=False' so that the encoded json contains unicode characters instead of unicode escape sequences
 class Encoder(json.JSONEncoder):
     def __init__(self):
-        super().__init__(use_decimal=False)
+        super().__init__(use_decimal=False, ensure_ascii=False)
 
     def default(self, obj):
         if isinstance(obj, decimal.Decimal):

tests/test_lambda_runtime_marshaller.py

@@ -37,3 +37,9 @@ def test_json_serializer_is_not_default_json(self):
         self.assertTrue(hasattr(internal_json, "YOLO"))
         self.assertFalse(hasattr(stock_json, "YOLO"))
         self.assertTrue(hasattr(simplejson, "YOLO"))
+
+    def test_to_json_unicode_encoding(self):
+        response = to_json({"price": "£1.00"})
+        self.assertEqual('{"price": "£1.00"}', response)
+        self.assertNotEqual('{"price": "\\u00a31.00"}', response)
+        self.assertEqual(19, len(response.encode('utf-8')))  # would be 23 bytes if a unicode escape was returned