Implement changes suggested by @jamadden.

src/zope/app/publisher/xmlrpc/README.rst

@@ -244,7 +244,7 @@ If you need to raise an error, the prefered way to do it is via an
   ...         self.request = request
   ...
   ...     def your_fault(self):
-  ...         return xmlrpclib.Fault(42, "It's your fault 😢!")
+  ...         return xmlrpclib.Fault(42, u"It's your fault \N{SNOWMAN}!")
 
 Now we'll register it as a view:
 
@@ -271,21 +271,18 @@ Now, when we call it, we get a proper XML-RPC fault:
 
   >>> try:
   ...     from xmlrpc.client import Fault
-  ...     expected = '<Fault 42: "It\'s your fault 😢!">'
+  ...     expected = '<Fault 42: "It\'s your fault \N{SNOWMAN}!">'
   ... except ImportError:  # PY2
   ...     from xmlrpclib import Fault
-  ...     expected = '<Fault 42: u"It\'s your fault \U0001f622!">'
+  ...     expected = '<Fault 42: u"It\'s your fault \u2603!">'
   >>> proxy = ServerProxy(wsgi_app, "http://mgr:mgrpw@localhost/")
   >>> # When dropping PY2 we can come back here to asserting the text of the
   >>> # exception:
   >>> try:
   ...     proxy.your_fault()
   ... except Fault as e:
-  ...     assert str(e) == expected, str(e)
-  ... except Exception as e:
-  ...     raise AssertionError('Raised %s instead of `Fault`!')
-  ... else:
-  ...     raise AssertionError('Nothing raised.')
+  ...     str(e) == expected
+  True
 
 
 DateTime values

src/zope/app/publisher/xmlrpc/testing.py

@@ -76,9 +76,10 @@ def request(self, host, handler, request_body, verbose=0):
                 headers)
 
         body = response.getBody()
-        if not isinstance(errmsg, bytes):
-            # Python 3
-            errmsg = errmsg.encode("ascii")
+        body = body if isinstance(body, bytes) else body.encode('latin-1')
+        errmsg = (errmsg
+                  if isinstance(errmsg, bytes)
+                  else errmsg.encode('ascii'))  # HTTP response lines are ASCII
         content = b'HTTP/1.0 ' + errmsg + b'\n\n' + body
 
         res = httplib.HTTPResponse(FakeSocket(content))