Merge pull request #4615 from niboshi/bp-4551-argument-exception-message

[backport] Improve chainer.utils.argument exception message

chainer/utils/argument.py

@@ -1,3 +1,6 @@
+import inspect
+
+
 def check_unexpected_kwargs(kwargs, **unexpected):
     for key, message in unexpected.items():
         if key in kwargs:
@@ -8,8 +11,11 @@ def parse_kwargs(kwargs, *name_and_values):
     values = [kwargs.pop(name, default_value)
               for name, default_value in name_and_values]
     if kwargs:
-        args = ', '.join(["'%s'" % arg for arg in kwargs.keys()])
-        raise TypeError('got unexpected keyword argument(s) %s' % args)
+        caller = inspect.stack()[1]
+        args = ', '.join(repr(arg) for arg in sorted(kwargs.keys()))
+        message = caller[3] + \
+            '() got unexpected keyword argument(s) {}'.format(args)
+        raise TypeError(message)
     return tuple(values)
 
 

tests/chainer_tests/utils_tests/test_argument.py

@@ -0,0 +1,24 @@
+import unittest
+
+import six
+
+from chainer import testing
+from chainer.utils.argument import parse_kwargs
+
+
+class TestArgument(unittest.TestCase):
+
+    def test_parse_kwargs(self):
+
+        def test(**kwargs):
+            return parse_kwargs(kwargs, ('foo', 1), ('bar', 2))
+
+        self.assertEqual(test(), (1, 2))
+        self.assertEqual(test(bar=1, foo=2), (2, 1))
+
+        msg = "test\(\) got unexpected keyword argument\(s\) 'ham', 'spam'"
+        with six.assertRaisesRegex(self, TypeError, msg):
+            test(spam=1, ham=2)
+
+
+testing.run_module(__name__, __file__)