FIX: type of body for MockupResponse

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * [#75](https://gitlab.indiscale.com/caosdb/src/caosdb-pylib/-/issues/75), [#103](https://gitlab.indiscale.com/caosdb/src/caosdb-pylib/-/issues/103) Fixed JSON schema to allow more sections, and correct requirements for
   password method.
+- `read()` of MockupResponse returns now an appropriate type on modern systems
 
 ### Security ###
 

src/caosdb/connection/mockup.py

@@ -26,6 +26,7 @@ up a tcp connection."""
 
 from __future__ import unicode_literals, print_function
 from io import StringIO
+from sys import hexversion
 from .connection import CaosDBServerConnection, CaosDBHTTPResponse
 
 
@@ -56,7 +57,10 @@ class MockUpResponse(CaosDBHTTPResponse):
 
     def read(self, size=-1):
         """Return the body of the response."""
-        return self.response.read(size)
+        if hexversion < 0x03000000:
+            return self.response.read(size)
+        else:
+            return self.response.read(size).encode()
 
     def getheader(self, name, default=None):
         """Get the contents of the header `name`, or `default` if there is no