Fixes to frontend tests.

Mostly robustness and isolation improvements.

IPython/frontend/prefilterfrontend.py

@@ -64,13 +64,18 b' class PrefilterFrontEnd(LineFrontEndBase):'
 
     debug = False
     
-    def __init__(self, ipython0=None, *args, **kwargs):
+    def __init__(self, ipython0=None, argv=None, *args, **kwargs):
         """ Parameters:
             -----------
 
             ipython0: an optional ipython0 instance to use for command
             prefiltering and completion.
+
+            argv : list, optional
+              Used as the instance's argv value.  If not given, [] is used.
         """
+        if argv is None:
+            argv = []
         # This is a hack to avoid the IPython exception hook to trigger
         # on exceptions (https://bugs.launchpad.net/bugs/337105)
         # XXX: This is horrible: module-leve monkey patching -> side
@@ -98,7 +103,7 b' class PrefilterFrontEnd(LineFrontEndBase):'
             old_rawinput = __builtin__.raw_input
             __builtin__.raw_input = my_rawinput
             # XXX: argv=[] is a bit bold.
-            ipython0 = make_IPython(argv=[], 
+            ipython0 = make_IPython(argv=argv, 
                                     user_ns=self.shell.user_ns,
                                     user_global_ns=self.shell.user_global_ns)
             __builtin__.raw_input = old_rawinput

IPython/frontend/tests/test_prefilterfrontend.py

@@ -12,14 +12,16 b' __docformat__ = "restructuredtext en"'
 #  in the file COPYING, distributed as part of this software.
 #-------------------------------------------------------------------------------
 
+from copy import copy, deepcopy
 from cStringIO import StringIO
 import string
 
 from nose.tools import assert_equal
 
-from IPython.ipapi import get as get_ipython0
 from IPython.frontend.prefilterfrontend import PrefilterFrontEnd
-from copy import copy, deepcopy
+from IPython.ipapi import get as get_ipython0
+from IPython.testing.plugin.ipdoctest import default_argv
+
 
 def safe_deepcopy(d):
     """ Deep copy every key of the given dict, when possible. Elsewhere
@@ -45,7 +47,7 b' class TestPrefilterFrontEnd(PrefilterFrontEnd):'
 
     def __init__(self):
         self.out = StringIO()
-        PrefilterFrontEnd.__init__(self)
+        PrefilterFrontEnd.__init__(self,argv=default_argv())
         # Some more code for isolation (yeah, crazy)
         self._on_enter()
         self.out.flush()
@@ -64,7 +66,7 b' def isolate_ipython0(func):'
     """ Decorator to isolate execution that involves an iptyhon0.
 
         Notes
-        ------
+        -----
 
         Apply only to functions with no arguments. Nose skips functions
         with arguments.
@@ -153,6 +155,12 b' def test_magic():'
         This test is fairly fragile and will break when magics change.
     """
     f = TestPrefilterFrontEnd()
+    # Before checking the interactive namespace, make sure it's clear (it can
+    # otherwise pick up things stored in the user's local db)
+    f.input_buffer += '%reset -f'
+    f._on_enter()
+    f.complete_current_input()
+    # Now, run the %who magic and check output
     f.input_buffer += '%who'
     f._on_enter()
     out_value = f.out.getvalue()