Expand function snippet tests for kwargs

tests/snippets/func_defaults.py

@@ -10,11 +10,19 @@ except TypeError:
 else:
     assert False, 'no TypeError raised: 1 arg to no_args'
 
+try:
+    no_args(kw='should fail')
+except TypeError:
+    pass
+else:
+    assert False, 'no TypeError raised: kwarg to no_args'
+
 
 def one_arg(arg):
-    pass
+    return arg
 
 one_arg('one_arg')
+assert "arg" == one_arg(arg="arg")
 
 try:
     one_arg()
@@ -23,6 +31,13 @@ except TypeError:
 else:
     assert False, 'no TypeError raised: no args to one_arg'
 
+try:
+    one_arg(wrong_arg='wont work')
+except TypeError:
+    pass
+else:
+    assert False, 'no TypeError raised: incorrect kwarg to one_arg'
+
 try:
     one_arg('one_arg', 'two_arg')
 except TypeError:
@@ -30,12 +45,27 @@ except TypeError:
 else:
     assert False, 'no TypeError raised: two args to one_arg'
 
+try:
+    one_arg('one_arg', extra_arg='wont work')
+except TypeError:
+    pass
+else:
+    assert False, 'no TypeError raised: extra kwarg to one_arg'
+
+try:
+    one_arg('one_arg', arg='duplicate')
+except TypeError:
+    pass
+else:
+    assert False, 'no TypeError raised: same pos and kwarg to one_arg'
+
 
 def one_default_arg(arg="default"):
     return arg
 
 assert 'default' == one_default_arg()
 assert 'arg' == one_default_arg('arg')
+assert 'kwarg' == one_default_arg(arg='kwarg')
 
 try:
     one_default_arg('one_arg', 'two_arg')
@@ -64,3 +94,18 @@ except TypeError:
     pass
 else:
     assert False, 'no TypeError raised: three args to one_normal_one_default_arg'
+
+
+def two_pos(a, b):
+    return (a, b)
+
+assert ('a', 'b') == two_pos('a', 'b')
+assert ('a', 'b') == two_pos(b='b', a='a')
+
+
+def kwargs_are_variable(x=[]):
+    x.append(1)
+    return x
+
+assert [1] == kwargs_are_variable()
+assert [1, 1] == kwargs_are_variable()