Add conflict_handler parameter as attribut in Command class

Adding conflict_handler as attribut in the Command class in order to be
able to take control of this parameter and change to different behavior
that argparse is handling: error / resolve / ignore.

Callers will be able to override it and get a proper Parser object.

Change-Id: I327ece99a04bc8b2ebfa554dea643b1f2a456336

2 files changed, 48 insertions, 1 deletions

diff --git a/cliff/command.py b/cliff/command.py
index f8d0501..0a02525 100644
--- a/cliff/command.py
+++ b/cliff/command.py
@@ -74,6 +74,7 @@ class Command(object, metaclass=abc.ABCMeta):
     """
 
     deprecated = False
+    conflict_handler = 'ignore'
 
     _description = ''
     _epilog = None
@@ -156,7 +157,7 @@ class Command(object, metaclass=abc.ABCMeta):
             epilog=self.get_epilog(),
             prog=prog_name,
             formatter_class=_argparse.SmartHelpFormatter,
-            conflict_handler='ignore',
+            conflict_handler=self.conflict_handler,
         )
         for hook in self._hooks:
             hook.obj.get_parser(parser)
diff --git a/cliff/tests/test_command.py b/cliff/tests/test_command.py
index 29c8c33..c9513d0 100644
--- a/cliff/tests/test_command.py
+++ b/cliff/tests/test_command.py
@@ -172,3 +172,49 @@ class TestArgumentParser(base.TestBase):
         args = parser.parse_args(['-z', 'foo', 'a', 'b'])
         self.assertEqual(args.zippy, 'foo')
         self.assertEqual(args.zero, 'zero-default')
+
+    def test_with_conflict_handler(self):
+        cmd = TestCommand(None, None)
+        cmd.conflict_handler = 'resolve'
+        parser = cmd.get_parser('NAME')
+        self.assertEqual(parser.conflict_handler, 'resolve')
+
+    def test_raise_conflict_argument_error(self):
+        cmd = TestCommand(None, None)
+        parser = cmd.get_parser('NAME')
+        parser.add_argument(
+            '-f', '--foo',
+            dest='foo',
+            default='foo',
+        )
+        self.assertRaises(
+            argparse.ArgumentError,
+            parser.add_argument,
+            '-f',
+        )
+
+    def test_resolve_conflict_argument(self):
+        cmd = TestCommand(None, None)
+        cmd.conflict_handler = 'resolve'
+        parser = cmd.get_parser('NAME')
+        parser.add_argument(
+            '-f', '--foo',
+            dest='foo',
+            default='foo',
+        )
+        parser.add_argument(
+            '-f', '--foo',
+            dest='foo',
+            default='bar',
+        )
+        args = parser.parse_args(['a', 'b'])
+        self.assertEqual(args.foo, 'bar')
+
+    def test_wrong_conflict_handler(self):
+        cmd = TestCommand(None, None)
+        cmd.conflict_handler = 'wrong'
+        self.assertRaises(
+            ValueError,
+            cmd.get_parser,
+            'NAME',
+        )