Unit Testing of parser method using pytest

Question

This is my first time using pytest. All feedback for this test case is much appreciated.

import pytest
from mock import mock_open, patch
def get_file_contents(file_data):
 with patch.object('builtins.open', mock_open(read_data=file_data)) as mock:
 with open('mocked_file') as f:
 return (line for line in f.readlines())
@pytest.fixture(scope="module")
def text_parser(request):
 from tparse import TextParser
 file_data = getattr(request.module, 'file_contents')
 tparse = TextParser(file_data)
 def fin():
 tparse.close()
 request.addfinalizer(fin)
 return tparse
def test_get_system_entry(self):
 file_data = 'dc nyc server server001 ipaddress 10.10.10.10'
 file_iterable = get_file_contents(file_data)
 assert file_iterable == file_data

Answer 1

I'm not familiar using py.test, but here are some comments I have after reading your code:

1. There are no comments - this would be helpful to the reader.
2. In text_parser, you have from tparse import TextParser. I would advise moving this import to the top of the file, for readability.
3. What is your code trying to do with these tests? What are you testing?

• fr00z1: Thanks for the feedback Ryan. I was trying to follow the examples from py.test where it seems like including the imports in text fixtures is a pattern, however had I been performing traditional unit tests, I would have moved the imports to the top of the file. However, I am in agreement with you, and will most likely move the imports to the top of the file anyway. Currently I am testing a method that parses a string returned from an iterable. So basically open a file, read each line in the file, and the method will return the entry once the pattern is found.
• fr00z1: Also, apologize for the lack of comments. Was trying to be descriptive in the code itself, however it will be something I keep in mind in the future so I can be respectful of ppls time. Thanks for taking the time to look at this.

Answer 2

I don't understand this test:

def test_get_system_entry(self):
 file_data = 'dc nyc server server001 ipaddress 10.10.10.10'
 file_iterable = get_file_contents(file_data)
 assert file_iterable == file_data

The name of the test method suggests testing of getting "system entry". Inside, I see a string (file_data), and something that appears to be an iterable (file_iterable), and a call to get_file_contents, such that this expression is expected to be true:

file_data == get_file_contents(file_data)

So, we test getting a system entry by verifying that x == get_file_contents(x) ? I don't know what to make of that.

A good unit test case should be:

• perfectly clear
• easy to read and understand without deciphering
• have a good, descriptive name

And what is the self parameter for? "self" is used as the first parameter of class methods. But the test_get_system_entry method is not within a class, and the parameter is not used anyway. This is confusing code.