在单元测试中导入库的位置？ 蟒蛇

Question

I have to write a test file like this:

import unittest

from mylibrary import some_crazy_func

class TestSomething(unittest.TestCase):
    def test_some_crazy_func_that_needs_io_open(self):
        # Opens file
        # Calls function
        # assert outputs

But I'm unsure where is the "pythonic location" where I should import the library (let's say io ).

Should it be at the top:

import io
import unittest

from mylibrary import some_crazy_func

class TestSomething(unittest.TestCase):
    def test_some_crazy_func_that_needs_io_open(self):
         expected = ['abc', 'def', 'xyz']
         with io.open('somestaticfile.txt', 'r') as fin:
             outputs = [some_crazy_func(line) for line in fin]
         assert outputs == expected

Or within the TestCase 's function:

import unittest

from mylibrary import some_crazy_func

class TestSomething(unittest.TestCase):
    def test_some_crazy_func_that_needs_io_open(self):
         import io
         expected = ['abc', 'def', 'xyz']
         with io.open('somestaticfile.txt', 'r') as fin:
             outputs = [some_crazy_func(line) for line in fin]
         assert outputs == expected

Or is it before the TestCase function and at the object initialization:

import unittest

from mylibrary import some_crazy_func

class TestSomething(unittest.TestCase):
    import io
    def test_some_crazy_func_that_needs_io_open(self):
         expected = ['abc', 'def', 'xyz']
         with io.open('somestaticfile.txt', 'r') as fin:
             outputs = [some_crazy_func(line) for line in fin]
         assert outputs == expected

Answer 1

See PEP8: https://www.python.org/dev/peps/pep-0008/#id23

It states,

Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants.