Revisions subject to comments on PR #100

Additionally, reverted FakeSystemExit subclassing Exception, but added
an explicit __init__ so that we can emulate the SystemExit.code
functionality without having to change the superclass.

pubs/pubs_cmd.py

@@ -69,7 +69,6 @@ def execute(raw_args=sys.argv):
                                          prog="pubs", add_help=True)
         parser.add_argument('--version', action='version', version=__version__)
         subparsers = parser.add_subparsers(title="valid commands", dest="command")
-        #subparsers.required = True
 
         # Populate the parser with core commands
         for cmd_name, cmd_mod in CORE_CMDS.items():
@@ -86,11 +85,11 @@ def execute(raw_args=sys.argv):
 
         # Parse and run appropriate command
         # if no command, print help and exit peacefully (as '--help' does)
-        args = parser.parse_args(remaining_args)
+        args = parser.parse_args(remaining_args) 
-
         if not args.command:
-            parser.print_help()
+            ui.error("Too few arguments!\n")
-            sys.exit(0)
+            parser.print_help(file=sys.stderr)
+            sys.exit(2)
 
         args.prog = "pubs"  # FIXME?
         args.func(conf, args)

tests/test_usecase.py

@@ -29,14 +29,21 @@ PRINT_OUTPUT   = False
 CAPTURE_OUTPUT = True
 
 
-class FakeSystemExit(SystemExit):
+class FakeSystemExit(Exception):
     """\
     SystemExit exceptions are replaced by FakeSystemExit in the execute_cmds()
     function, so they can be catched by ExpectedFailure tests in Python 2.x.
 
     If a code is expected to raise SystemExit, catch FakeSystemExit instead.
+
+    Added explicit __init__ so SystemExit.code functionality could be emulated.
+    Taking form from https://stackoverflow.com/a/26938914/1634191
     """
-    pass
+    def __init__(self, message, code=None, *args):
+        self.message = message
+        self.code = code
+
+        super(FakeSystemExit, self).__init__(message, *args)
 
 
 # code for fake fs
@@ -131,7 +138,7 @@ class CommandTestCase(fake_env.TestFakeFs):
             exc_class, exc, tb = sys.exc_info()
             if sys.version_info.major == 2:
                 # using six to avoid a SyntaxError in Python 3.x
-                six.reraise(FakeSystemExit, *exc.args, exc_traceback=tb)
+                six.reraise(FakeSystemExit, FakeSystemExit(*exc.args), tb)
             else:
                 raise FakeSystemExit(*exc.args).with_traceback(tb)
 
@@ -189,6 +196,13 @@ class URLContentTestCase(DataCommandTestCase):
 
 class TestAlone(CommandTestCase):
 
+    def test_alone_misses_command(self):
+        with self.assertRaises(FakeSystemExit) as cm:
+            self.execute_cmds(['pubs'])
+            self.assertEqual(cm.exception.code, 2)
+
+
+    @unittest.skipIf(sys.version_info.major == 2, "not supported for Python2")
     def test_alone_prints_help(self):
         # capturing the output of `pubs --help` is difficult because argparse
         # raises as SystemExit(0) after calling `print_help`, and this gets
@@ -196,15 +210,14 @@ class TestAlone(CommandTestCase):
         # `pubs --help` isn't too easy unless substantially reorganization of
         # the parser and testing context is made.  instead, the exit codes of
         # the two usecases are compared.
-        self.execute_cmds(['pubs init'])
 
         with self.assertRaises(FakeSystemExit) as cm1:
             self.execute_cmds(['pubs'])
 
         with self.assertRaises(FakeSystemExit) as cm2:
-            self.execute_cmds(['pubs --help'])
+            self.execute_cmds(['pubs', '--help'])
 
-        self.assertEqual(cm1.exception.code, cm2.exception.code, 0)
+        self.assertEqual(cm1.exception.code, cm2.exception.code, 2)
 
 
 class TestInit(CommandTestCase):