Disallow arguments in chain mode and no longer expose leftover args.

3 files changed, 57 insertions, 1 deletions

diff --git a/CHANGES b/CHANGES
index a138957..196af80 100644
--- a/CHANGES
+++ b/CHANGES
@@ -36,6 +36,10 @@ Version 6.0
 - Unittests now always force a certain virtual terminal width.
 - Added support for allowing dashes to indicate standard streams to the
   `Path` type.
+- Multi commands in chain mode no longer propagate arguments left over
+  from parsing to the callbacks.  It's also now disallowed through an
+  exception that arguments are attached to multi commands if chain mode
+  is enabled.
 
 Version 5.1
 -----------
diff --git a/click/core.py b/click/core.py
index f7cbfc2..a580e42 100644
--- a/click/core.py
+++ b/click/core.py
@@ -927,6 +927,12 @@ class MultiCommand(Command):
         #: overridden with the :func:`resultcallback` decorator.
         self.result_callback = result_callback
 
+        if self.chain:
+            for param in self.params:
+                if isinstance(param, Argument):
+                    raise RuntimeError('Multi commands in chain mode cannot '
+                                       'have other arguments.')
+
     def collect_usage_pieces(self, ctx):
         rv = Command.collect_usage_pieces(self, ctx)
         rv.append(self.subcommand_metavar)
@@ -1041,6 +1047,9 @@ class MultiCommand(Command):
         # set to ``*`` to inform the command that subcommands are executed
         # but nothing else.
         with ctx:
+            # The master command does not receive any arguments.  That
+            # would be silly.
+            ctx.args = []
             ctx.invoked_subcommand = args and '*' or None
             Command.invoke(self, ctx)
 
@@ -1054,7 +1063,7 @@ class MultiCommand(Command):
                                            allow_extra_args=True,
                                            allow_interspersed_args=False)
                 contexts.append(sub_ctx)
-                args = sub_ctx.args
+                args, sub_ctx.args = sub_ctx.args, []
 
             rv = []
             for sub_ctx in contexts:
diff --git a/tests/test_chain.py b/tests/test_chain.py
index 9f86a8f..aee6f2d 100644
--- a/tests/test_chain.py
+++ b/tests/test_chain.py
@@ -1,4 +1,6 @@
+import sys
 import click
+import pytest
 
 
 def test_basic_chaining(runner):
@@ -152,3 +154,44 @@ def test_pipeline(runner):
         'FOO',
         'BAR',
     ]
+
+
+def test_args_and_chain(runner):
+    def debug():
+        click.echo('%s=%s' % (
+            sys._getframe(1).f_code.co_name,
+            '|'.join(click.get_current_context().args),
+        ))
+
+    @click.group(chain=True)
+    def cli():
+        debug()
+
+    @cli.command()
+    def a():
+        debug()
+
+    @cli.command()
+    def b():
+        debug()
+
+    @cli.command()
+    def c():
+        debug()
+
+    result = runner.invoke(cli, ['a', 'b', 'c'])
+    assert not result.exception
+    assert result.output.splitlines() == [
+        'cli=',
+        'a=',
+        'b=',
+        'c=',
+    ]
+
+
+def test_multicommand_no_args(runner):
+    with pytest.raises(RuntimeError):
+        @click.group(chain=True)
+        @click.argument('forbidden')
+        def cli():
+            pass