Fix various problems highlighted by the test suite.

IPython/core/interactiveshell.py

@@ -2454,7 +2454,7 b' class InteractiveShell(SingletonConfigurable, Magic):'
                           # Skip our own frame in searching for locals:
                           sys._getframe(depth+1).f_locals # locals
                           )
-        return str(res).decode(res.codec)
+        return py3compat.str_to_unicode(str(res), res.codec)
 
     def mktempfile(self, data=None, prefix='ipython_edit_'):
         """Make a new tempfile and return its filename.

IPython/testing/globalipapp.py

@@ -23,12 +23,12 b' from __future__ import print_function'
 import __builtin__ as builtin_mod
 import os
 import sys
-from types import MethodType
 
 # our own
 from . import tools
 
 from IPython.utils import io
+from IPython.utils import py3compat
 from IPython.frontend.terminal.interactiveshell import TerminalInteractiveShell
 
 #-----------------------------------------------------------------------------
@@ -204,11 +204,10 b' def start_ipython():'
     # Modify the IPython system call with one that uses getoutput, so that we
     # can capture subcommands and print them to Python's stdout, otherwise the
     # doctest machinery would miss them.
-    shell.system = MethodType(xsys, shell, TerminalInteractiveShell)
+    shell.system = py3compat.MethodType(xsys, shell)
                        
 
-    shell._showtraceback = MethodType(_showtraceback, shell,
-                                      TerminalInteractiveShell)
+    shell._showtraceback = py3compat.MethodType(_showtraceback, shell)
 
     # IPython is ready, now clean up some global state...
     

IPython/utils/process.py

@@ -27,6 +27,7 b' else:'
     from ._process_posix import _find_cmd, system, getoutput
 
 from ._process_common import getoutputerror
+from IPython.utils import py3compat
 
 #-----------------------------------------------------------------------------
 # Code
@@ -115,7 +116,7 b' def arg_split(s, posix=False):'
     # At least encoding the input when it's unicode seems to help, but there
     # may be more problems lurking.  Apparently this is fixed in python3.
     is_unicode = False
-    if isinstance(s, unicode):
+    if (not py3compat.PY3) and isinstance(s, unicode):
         is_unicode = True
         s = s.encode('utf-8')
     lex = shlex.shlex(s, posix=posix)

IPython/utils/py3compat.py

@@ -1,6 +1,7 b''
 # coding: utf-8
 """Compatibility tricks for Python 3. Mainly to do with unicode."""
 import sys
+import types
 
 orig_open = open
 
@@ -43,6 +44,8 b' if sys.version_info[0] >= 3:'
         return s.isidentifier()
     
     open = orig_open
+    
+    MethodType = types.MethodType
 
 else:
     PY3 = False
@@ -83,6 +86,9 b' else:'
         
         def __exit__(self, etype, value, traceback):
             self.f.close()
+    
+    def MethodType(func, instance):
+        return types.MethodType(func, instance, type(instance))
 
 def execfile(fname, glob, loc=None):
     loc = loc if (loc is not None) else glob