"TypeError" can give a misleading message

[markon]

BPO	15098
Nosy	@bitdancer

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2012-06-17.15:43:49.702>
created_at = <Date 2012-06-17.15:39:27.897>
labels = ['interpreter-core', 'type-bug']
title = '"TypeError" can give a misleading message'
updated_at = <Date 2012-06-17.15:43:49.701>
user = 'https://bugs.python.org/markon'

bugs.python.org fields:

activity = <Date 2012-06-17.15:43:49.701>
actor = 'r.david.murray'
assignee = 'none'
closed = True
closed_date = <Date 2012-06-17.15:43:49.702>
closer = 'r.david.murray'
components = ['Interpreter Core']
creation = <Date 2012-06-17.15:39:27.897>
creator = 'markon'
dependencies = []
files = []
hgrepos = []
issue_num = 15098
keywords = []
message_count = 2.0
messages = ['163072', '163073']
nosy_count = 2.0
nosy_names = ['r.david.murray', 'markon']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue15098'
versions = ['Python 2.7']

[markon]

Suppose that you have an instance method that takes 2 arguments: one is required, while the other is a keyword argument.

If you call that method without passing the required argument, but instead you only set the keyword argument, then you will get a TypeError exception, claiming this ...
-> TypeError: 'method' takes at least 2 arguments (2 given)

(I am referring to this particular method: http://www.voidspace.org.uk/python/mock/mock.html#mock.Mock.mock_add_spec)

@patch('xyz.subprocess.Popen')
def test_xyz(self, mocked_popen):
mocked_popen.mock_add_spec(spec_set=True)

I think the right error message should be different, in particular should be this:
-> TypeError: 'method' takes at least 2 arguments (1 given)

[bitdancer]

This is fixed in Python3:

>>> def foo(a, b=None):
...   pass
... 
>>> foo(b=1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: foo() missing 1 required positional argument: 'a'