python global name 'collections' is not defined even I imported collections

Question

The following is config.py:

from collections import OrderedDict
def test_config(fileName):
    tp_dict = collections.OrderedDict()
    with open("../../config/" + fileName, 'r') as myfile:
        file_str = myfile.read().replace(' ', '').split('\n')
    tp_list = []
    for i, x in enumerate(file_str):
        x = x.strip()
        try:
            key = x[:x.index(':')].strip()
            value = x[x.index(':')+1:]
            if key == 'testpoint':
                pass
            else:
                tp_dict[key] = value.strip().split(',')
        except ValueError,e:
            pass
        if i % 4 == 0 and i != 0:
            tp_list.append(tp_dict.copy())   
    return tp_list

I'm using the function in another file test.py:

import config
a = config.test_config('test.txt')

NameError: global name 'collections' is not defined

But if I copy paste the whole code from config.py to the top of test.py, and then use the function, then I have no error(See code below). Can anybody explain this to me please? I'm so so so confused. Thank you very much!

"""
This is test.py
"""
from collections import OrderedDict
def test_config(fileName):
    tp_dict = collections.OrderedDict()
    with open("../../config/" + fileName, 'r') as myfile:
        file_str = myfile.read().replace(' ', '').split('\n')
    tp_list = []
    for i, x in enumerate(file_str):
        x = x.strip()
        try:
            key = x[:x.index(':')].strip()
            value = x[x.index(':')+1:]
            if key == 'testpoint':
                pass
            else:
                tp_dict[key] = value.strip().split(',')
        except ValueError,e:
            pass
        if i % 4 == 0 and i != 0:
            tp_list.append(tp_dict.copy())   
    return tp_list
a = test_config('test.txt')

Solution 1

Change from collections import OrderedDict to import collections.

Solution 2

Option 1: Change

from collections import OrderedDict

to

import collections

option 2:

Change

collections.OrderedDict()

to

OrderedDict()

Solution 3

You don't import collections, you only import from collections. Simply write OrderedDict instead of collections.OrderedDict.

Comments

[Catherine]

You're right. But why it doesn't complain an error in the test.py then?