Develop Reference

How to import a class from another file in python?

Im new to python and have looked at various stack overflow posts. i feel like this should work but it doesnt. How do you import a class from another file in python?
This folder structure
src/example/ClassExample
src/test/ClassExampleTest
I have this class
class ClassExample:
def __init__(self):
pass
def helloWorld(self):
return "Hello World!"
I have this test class
import unittest
from example import ClassExample
class ClassExampleTest(unittest.TestCase):
def test_HelloWorld(self):
hello = ClassExample()
self.assertEqual("Hello World!", hello.helloWorld())
if __name__ == '__main__':
unittest.main()
When the unit test runs the object is None:
AttributeError: 'NoneType' object has no attribute 'helloWorld'
What's wrong with this? How do you import a class in python?

If you're using Python 3, then imports are absolute by default. This means that import example will look for an absolute package named example, somewhere in the module search path.
So instead, you probably want a relative import. This is useful when you want to import a module that is relative the module doing the importing. In this case:
from ..example.ClassExample import ClassExample
I'm assuming that your folders are Python packages, meaning that they contain __init__.py files. So your directory structure would look like this.
src
|-- __init__.py
|-- example
| |-- __init__.py
| |-- ClassExample.py
|-- test
| |-- __init__.py
| |-- ClassExampleTest.py

Allure-report empty when allure-results have multiple result folders

The allure-results folders is in the following structure.
allure-results/
|-- assertions1
| |-- 2f429779-3c86-4958-8e8b-e9a03a25cd20-attachment.txt
| |-- 312890b7-fd56-4c65-bee9-14d76ff4a58e-testsuite.xml
| |-- 3f385845-14cc-4411-86c2-06e35a76b2ad-attachment.txt
| |-- 59f04042-8f20-4c11-b611-b5364e892556-attachment.txt
| |-- 8829ef83-06d2-425d-b5c6-dc2e09b8b3b2-attachment.svg
| `-- e37938ed-0c9b-4ac4-99d5-0e80f240a79e-attachment.txt
|-- assertions2
| |-- 0adb3f17-3e46-48e3-bdc9-9603b6d31084-attachment.txt
| |-- 0fd3980a-d55b-49b8-8bdd-c56b7282008d-attachment.txt
| |-- 20f132d1-8b4d-453c-9cea-53c7f59ff12e-attachment.svg
| |-- 2ed67517-f700-4cac-85f3-93aac1529828-attachment.txt
| |-- 45246942-4479-468a-bf29-72f2f19dfce9-testsuite.xml
| |-- 80b5e955-6cc3-4ce6-a954-ce46f554b810-attachment.txt
| |-- a01f2abf-52fa-47ff-99c0-a43a5bd0756b-attachment.txt
| |-- ce094c0b-256a-4bf6-92b3-17d2fadff3ca-attachment.txt
| |-- e95eedf9-0d8f-49d6-8fd6-c02d4e1181bd-attachment.txt
| `-- f7891f5d-e115-4031-a56a-203bb2f73d38-attachment.txt
|-- environment.xml
|-- assertions3
| |-- c052da82-213b-4db2-8a33-7e96e501907c-testsuite.xml
| `-- fd72c264-f037-4a02-b797-5407dd50a297-attachment.txt
|-- assertions4
| |-- 8d8df3dd-47e1-416e-acb7-6ef62d529c0f-attachment.txt
| `-- c2dadf11-fcbc-4027-97bc-98849be24540-testsuite.xml
|-- assertions5
| |-- ea11687b-7846-4bbb-923c-8cc62f7c69b5-attachment.txt
| `-- f24ddf31-a3f8-4feb-bf07-ba6465ee4555-testsuite.xml
`-- assertions6
|-- 08d24268-a755-4969-aa3b-5660951fd21d-testsuite.xml
`-- 6b4590bf-4df7-4e39-941e-63e1f902968a-attachment.txt
We can see that there are multiple testsuite results in it along with environment.xml.
I am trying to generate an allure report for it. Latest allurecommandline is installed.
When I try to run the following command, the allure report is empty.
allure generate allure-results/
It works when I give an individual result directory.
allure generate allure-results/assertions1
I am looking for a way to make allure generate a report based on all the testsuite results folders present in the allure-results.
The testsuite results are generated using python nosetests.

You shouldn't create subdirectories. Every file should be in the allure-results directory (without subdirectories). For that reason, the files have random file names.
Like this:

Not sure if this is the best solution.
I used the following and it worked.
allure generate allure-results/*
Note: In order to get the environment.xml to be parsed by the allure, move it to another folder inside the results. I moved it to "allure-results/environment/environment.xml".

Function not defined when running tests in Python package

I am creating a Python package/library. My directory structure looks like this:
my_package/
|-- my_package/
| |-- tests/
| | |-- __init__.py
| | |-- my_tests.py
| |
| |-- __init__.py
| |-- main.py
|
|-- setup.py
I have all my functions in the main.py file:
def sum_nums(a,b):
res = a + b
return(res)
def mult_nums(a,b):
res = a * b
return(res)
def sub_nums(a,b):
res = a - b
return(res)
my_tests.py looks like this:
from unittest import TestCase
import my_package
def test_sum():
assert sum_nums(3,4) == 7
def test_mult():
assert mult_nums(3,4) == 12
def test_sub():
assert sub_nums(3,4) == -1
When I run my tests from the package root directory as follows:
python setup.py test
... I get the following error:
NameError: name 'sum_nums' is not defined
Is my package directory structure correct?
Am I missing an _ init _.py file?
Does every directory require an _ init _.py file?
Is it okay to place all my functions inside a single main.py file
without using if name == "main"?

You need to indicate that the functions under test came for the my_package package like:
from unittest import TestCase
import my_package
def test_sum():
assert my_package.sum_nums(3,4) == 7
def test_mult():
assert my_package.mult_nums(3,4) == 12
def test_sub():
assert my_package.sub_nums(3,4) == -1

tests should not be in the package so move it up one dir. See sanic or any other module in github for example. Your functions need to be available in init.py. You can import them like is done in sanic.
https://github.com/huge-success/sanic
You also need
from my_package import sum_nums, mult_nums, sub_nums
Or prefix with my_package.

ImportError: cannot import name 'foo'

I'm learning python and received my first error in line 3:
here is my code:
app.py
import logging.config
from flask import Flask, Blueprint
from platform import settings
app = Flask(__name__)
def main():
app.run(debug=settings.FLASK_DEBUG)
if __name__ == "__main__":
main()
and my file structure is like this:
project_name
|--platform
| |--api
| |--database
| |-- __init__.py
| |-- app.py
| |-- settings.py
|--logging.conf
|--requirements.txt
|--readme.md
|--setup.cfg
i use PyCharm IDE and execute in terminal: python platform\app.py
then i receive this error:
Traceback (most recent call last):
File "platform\app.py", line 4,
in
from platform import settings
ImportError: cannot import name 'settings'
any idea what's wrong here?
here is my settings.py
# Flask settings
FLASK_SERVER_NAME = 'localhost:5000'
FLASK_DEBUG = True # Do not use debug mode in production
# Flask-Restplus settings
RESTPLUS_SWAGGER_UI_DOC_EXPANSION = 'list'
RESTPLUS_VALIDATE = True
RESTPLUS_MASK_SWAGGER = False
RESTPLUS_ERROR_404_HELP = False
# MYSQL settings
MYSQL_DATABASE_URI = 'blablalba'
MYSQL_TRACK_MODIFICATIONS = False
PYMYSQL_CONNECTION = {
'host': '123.456.789.111',
'port': 3306,
'user': 'root',
'passwd': 'password',
'db': 'database'
}

You have a package named platform but you are attempting to execute a script in it. When you do that, the script is going to be run independently, with none of the package information because the script is not imported. To do a proper import and then run as a script, use the -m option:
python -m platform.app
This will import the script from the platform package, set up the dependencies correctly, etc.
Generally, you would want to place your executable script outside your main package for this exact reason. If you modify your folder structure to look like this, the command python app.py should run just fine because platform will be a recognized package:
project_name
|--platform
| |--api
| |--database
| |-- __init__.py
| |-- settings.py
|-- app.py
|--logging.conf
|--requirements.txt
|--readme.md
|--setup.cfg
Finally, as a minor nitpick, if you do decide to keep app.py at the package level rather than the project level, I would recommend using relative imports to get the settings:
from . import settings

You have everything setup fine, my guess is that you are using settings.py as a constants file. so instead of
from platform import settings
try to import the values from the file relatively (since both app.py and settings.py are in the same directory)
from settings import *
and then you can use them like
print(FLASK_SERVER_NAME)
Although this would work fine, but I like to do it a bit differently, so as to not end up scratching my head trying to figure out what constant or function comes from where. Here are my 2 cents
import settings.py as configs # or any variable name you want to use
print(configs.FLASK_SERVER_NAME)
# more understandable as now you know FLASK_SERVER_NAME is coming from configs

You can straight away use import settings instead

Get absolute path in Python

I'm having a problem with assigning static files containing resources.
My working directory structure is:
|- README.md
|- nlp
| |-- morpheme
| |-- |-- morpheme_builder.py
| |-- fsa_setup.py
| - tests
| |-- test_fsa.py
| - res
| |-- suffixes.xml
The code for fsa_setup.py is:
class FSASetup():
fsa = None
def get_suffixes():
list_suffix = list()
file = os.path.realpath("../res/suffixes.xml")
.....
if __name__ == "__main__":
FSASetup.get_suffixes()
The code for morpheme_builder.py is:
class MorphemeBuilder:
def get_all_words_from_fsa(self):
......
if __name__ == "__main__":
FSASetup.get_suffixes()
When it is called in fsa_setup.py, the file path's value is '\res\suffixes.xml' and that is correct, but when the other case realized, the file path value is '\nlp\res\suffixes.xml'.
I know how it works like this. So how can I give the path of the resource to the file.

The problem is that morpheme_builder.py is in the directory morphem. So when you say ../res/suffixes.xml it will go on directory back ... so it will go to nlp/res/suffixes.xml. What about if you use os.path.abspath("../res/suffixes.xml")?