Manage and propagate argv correctly.

All Application objects should take argv in their constructor, akin to how
the standard signature of C programs is "main(int argc, char *argv)".  This
makes it possible to initialize them from code with different command-line
options (otherwise, they end up directly accessing sys.argv[1:] via
argparse).

IPython/config/loader.py

@@ -301,18 +301,39 b' class ArgParseConfigLoader(CommandLineConfigLoader):'
     # arguments = [(('-f','--file'),dict(type=str,dest='file'))]
     arguments = ()
 
-    def __init__(self, *args, **kw):
+    def __init__(self, argv=None, *args, **kw):
         """Create a config loader for use with argparse.
 
-        The args and kwargs arguments here are passed onto the constructor
-        of :class:`argparse.ArgumentParser`.
+        With the exception of argv, other args and kwargs arguments here are
+        passed onto the constructor of :class:`argparse.ArgumentParser`.
+
+        Parameters
+        ----------
+
+        argv : optional, list
+          If given, used to read command-line arguments from, otherwise
+          sys.argv[1:] is used.
         """
         super(CommandLineConfigLoader, self).__init__()
+        if argv == None:
+            argv = sys.argv[1:]
+        self.argv = argv
         self.args = args
         self.kw = kw
 
     def load_config(self, args=None):
-        """Parse command line arguments and return as a Struct."""
+        """Parse command line arguments and return as a Struct.
+
+        Parameters
+        ----------
+
+        args : optional, list
+          If given, a list with the structure of sys.argv[1:] to parse arguments
+          from.  If not given, the instance's self.argv attribute (given at
+          construction time) is used."""
+        
+        if args is None:
+            args = self.argv
         self._create_parser()
         self._parse_args(args)
         self._convert_to_config()
@@ -337,12 +358,9 b' class ArgParseConfigLoader(CommandLineConfigLoader):'
             argument[1].setdefault('default', NoConfigDefault)
             self.parser.add_argument(*argument[0],**argument[1])
 
-    def _parse_args(self, args=None):
-        """self.parser->self.parsed_data"""
-        if args is None:
-            self.parsed_data, self.extra_args = self.parser.parse_known_args()
-        else:
-            self.parsed_data, self.extra_args = self.parser.parse_known_args(args)
+    def _parse_args(self, args):
+        """self.parser->self.parsed_data""" 
+        self.parsed_data, self.extra_args = self.parser.parse_known_args(args)
 
     def _convert_to_config(self):
         """self.parsed_data->self.config"""

IPython/core/application.py

@@ -92,11 +92,14 b' class Application(object):'
     profile_name = None
     #: User's ipython directory, typically ~/.ipython/
     ipython_dir = None
+    #: A reference to the argv to be used (typically ends up being sys.argv[1:])
+    argv = None
 
     # Private attributes
     _exiting = False
 
-    def __init__(self):
+    def __init__(self, argv=None):
+        self.argv = sys.argv[1:] if argv is None else argv
         self.init_logger()
 
     def init_logger(self):
@@ -173,7 +176,7 b' class Application(object):'
 
     def create_command_line_config(self):
         """Create and return a command line config loader."""
-        return BaseAppArgParseConfigLoader(
+        return BaseAppArgParseConfigLoader(self.argv,
             description=self.description, 
             version=release.version
         )

IPython/core/ipapp.py

@@ -344,7 +344,7 b' class IPythonApp(Application):'
 
     def create_command_line_config(self):
         """Create and return a command line config loader."""
-        return IPythonAppCLConfigLoader(
+        return IPythonAppCLConfigLoader(self.argv,
             description=self.description, 
             version=release.version
         )
@@ -565,7 +565,8 b' class IPythonApp(Application):'
         if self.master_config.Global.interact:
             self.log.debug("Starting IPython's mainloop...")
             self.shell.mainloop()
-
+        else:
+            self.log.debug("IPython not interactive, start_app is no-op...")
 
 
 def load_default_config(ipython_dir=None):
@@ -584,4 +585,3 b' def launch_new_instance():'
     """Create and run a full blown IPython instance"""
     app = IPythonApp()
     app.start()
-