client: detect original frappy error class

The text part of the error report contains the original error
class - convert it to the frappy error class, if possible.
This makes the error messages on the client nicer, as the
error class would be duplicated in the error message on the
client side.

Change-Id: If2e0c3eb15ac2dd1b80a851ff42e4076557a325d

frappy/errors.py

@@ -22,6 +22,9 @@
 # *****************************************************************************
 """Define (internal) SECoP Errors"""
 
+import re
+from ast import literal_eval
+
 
 class SECoPError(RuntimeError):
     silent = False   # silent = True indicates that the error is already logged
@@ -121,8 +124,27 @@ class HardwareError(SECoPError):
     name = 'HardwareError'
 
 
+FRAPPY_ERROR = re.compile(r'(.*)\(.*\)$')
+
+
 def make_secop_error(name, text):
-    errcls = EXCEPTIONS.get(name, InternalError)
+    """create an instance of SECoPError from an error report
+
+    :param name: the error class from the SECoP error report
+    :param text: the second item of a SECoP error report
+    :return: the built instance of SECoPError
+    """
+    try:
+        # try to interprete the error text as a repr(<instance of SECoPError>)
+        # as it would be created by a Frappy server
+        cls, textarg = FRAPPY_ERROR.match(text).groups()
+        errcls = locals()[cls]
+        if errcls.name == name:
+            # convert repr(<string>) to <string>
+            text = literal_eval(textarg)
+    except Exception:
+        # probably not a Frappy server, or running a different version
+        errcls = EXCEPTIONS.get(name, InternalError)
     return errcls(text)