commands: Add usage to CommandError

mopidy/utils/command.py

@@ -5,7 +5,9 @@ import sys
 
 
 class CommandError(Exception):
-    pass
+    def __init__(self, message, usage=None):
+        self.message = message
+        self.usage = usage
 
 
 class ArgumentParser(argparse.ArgumentParser):
@@ -42,9 +44,12 @@ class Command(object):
     def format_usage(self, prog=None):
         actions = self._build()[1]
         prog = prog or os.path.basename(sys.argv[0])
+        return self._usage(actions, prog) + '\n'
+
+    def _usage(self, actions, prog):
         formatter = argparse.HelpFormatter(prog)
         formatter.add_usage(None, actions, [])
-        return formatter.format_help()
+        return formatter.format_help().strip()
 
     def format_help(self, prog=None):
         actions = self._build()[1]
@@ -89,16 +94,20 @@ class Command(object):
         for childname, child in self._children.items():
             child._subhelp(' '.join((name, childname)), result)
 
-    def parse(self, args):
-        return self._parse(args, argparse.Namespace(), self._defaults.copy())
+    def parse(self, args, prog=None):
+        prog = prog or os.path.basename(sys.argv[0])
+        return self._parse(
+            args, argparse.Namespace(), self._defaults.copy(), prog)
 
-    def _parse(self, args, namespace, defaults):
+    def _parse(self, args, namespace, defaults, prog):
         defaults.update(self._defaults)
-        parser = self._build()[0]
-        result, unknown = parser.parse_known_args(args, namespace)
+        parser, actions = self._build()
 
-        if unknown:
-            raise CommandError('Unknown command options.')
+        try:
+            result = parser.parse_args(args, namespace)
+        except CommandError as e:
+            e.usage = self._usage(actions, prog)
+            raise
 
         if not result._args:
             for attr, value in defaults.items():
@@ -108,8 +117,10 @@ class Command(object):
             result.command = self
             return result
 
-        child = self._children.get(result._args[0])
-        if not child:
-            raise CommandError('Invalid sub-command provided.')
+        child = result._args.pop(0)
+        if child not in self._children:
+            raise CommandError('unrecognized command: %s' % child,
+                               usage=self._usage(actions, prog))
 
-        return child._parse(result._args[1:], result, defaults)
+        return self._children[child]._parse(
+            result._args, result, defaults, ' '.join([prog, child]))

tests/utils/command_test.py

@@ -95,28 +95,46 @@ class CommandParsingTest(unittest.TestCase):
         cmd.add_argument('--bar', type=int)
 
         with self.assertRaises(command.CommandError) as cm:
-            cmd.parse(['--bar', b'zero'])
+            cmd.parse(['--bar', b'zero'], prog='foo')
 
         self.assertEqual(cm.exception.message,
                          "argument --bar: invalid int value: 'zero'")
+        self.assertEqual(cm.exception.usage, 'usage: foo [--bar BAR]')
+
+    @mock.patch('sys.argv')
+    def test_command_error_usage_prog(self, argv_mock):
+        argv_mock.__getitem__.return_value = '/usr/bin/foo'
+
+        cmd = command.Command()
+        cmd.add_argument('--bar', required=True)
+
+        with self.assertRaises(command.CommandError) as cm:
+            cmd.parse([])
+        self.assertEqual(cm.exception.usage, 'usage: foo --bar BAR')
+
+        with self.assertRaises(command.CommandError) as cm:
+            cmd.parse([], prog='baz')
+        self.assertEqual(cm.exception.usage, 'usage: baz --bar BAR')
 
     def test_missing_required(self):
         cmd = command.Command()
         cmd.add_argument('--bar', required=True)
 
         with self.assertRaises(command.CommandError) as cm:
-            cmd.parse([])
+            cmd.parse([], prog='foo')
 
         self.assertEqual(cm.exception.message, 'argument --bar is required')
+        self.assertEqual(cm.exception.usage, 'usage: foo --bar BAR')
 
     def test_missing_positionals(self):
         cmd = command.Command()
         cmd.add_argument('bar')
 
         with self.assertRaises(command.CommandError) as cm:
-            cmd.parse([])
+            cmd.parse([], prog='foo')
 
         self.assertEqual(cm.exception.message, 'too few arguments')
+        self.assertEqual(cm.exception.usage, 'usage: foo bar')
 
     def test_missing_positionals_subcommand(self):
         child = command.Command()
@@ -126,9 +144,30 @@ class CommandParsingTest(unittest.TestCase):
         cmd.add_child('bar', child)
 
         with self.assertRaises(command.CommandError) as cm:
-            cmd.parse(['bar'])
+            cmd.parse(['bar'], prog='foo')
 
         self.assertEqual(cm.exception.message, 'too few arguments')
+        self.assertEqual(cm.exception.usage, 'usage: foo bar baz')
+
+    def test_unknown_command(self):
+        cmd = command.Command()
+
+        with self.assertRaises(command.CommandError) as cm:
+            cmd.parse(['--help'], prog='foo')
+
+        self.assertEqual(
+            cm.exception.message, 'unrecognized arguments: --help')
+        self.assertEqual(cm.exception.usage, 'usage: foo')
+
+    def test_invalid_subcommand(self):
+        cmd = command.Command()
+        cmd.add_child('baz', command.Command())
+
+        with self.assertRaises(command.CommandError) as cm:
+            cmd.parse(['bar'], prog='foo')
+
+        self.assertEqual(cm.exception.message, 'unrecognized command: bar')
+        self.assertEqual(cm.exception.usage, 'usage: foo')
 
     def test_set_defaults(self):
         cmd = command.Command()