Question on unit testing
Goal: The goal is to use pyUnit in testCalc.py to unit test the simpleCalc object in calculator.py.
Problem: I cannot successfully import the simpleCalc object from calculator.py into testCalc.py when testCalc is run from a separate directory in the project.
Background: The unit test in testCalc.py runs perfectly fine when it's included in the same directory as calculator.py, but when I move it into a separate folder and try to import the simpleCalc object defined in calculator.py, I get an error. I am trying to learn how to use the pyUnit unit testing framework in a simple project and I'm clearly missing something basic about how to import modules for unit testing in a hierarchical directory structure. The basic calculator_test project described below is a simple project that I created to practice. You can see all the posts I've gone through already at the end of this post.
Ultimate Question: How can I import the simpleCalc object into testCalc.py with the directory hierarchy described below?
Github: https://github.com/jaybird4522/calculator_test/tree/unit_test
Here's my directory structure:
calculator_test/
calculatorAlgo/
__init__.py
calculator.py
test_calculatorAlgo/
__init__.py
testCalc.py
testlib/
__init__.py
testcase.py
Here's the calculator.py file, which describes the simpleCalc object I want to unit test:
# calculator.py
class simpleCalc(object):
def __init__(self):
self.input1 = 0
self.input2 = 0
def set(self, in1, in2):
self.input1 = in1
self.input2 = in2
def subtract(self, in1, in2):
self.set(in1, in2)
result = self.input1 - self.input2
return result
Here's the testCalc.py file, which contains the unit tests:
# testCalc.py
import unittest
from calculatorAlgo.calculator import simpleCalc
class testCalc(unittest.TestCase):
# set up the tests by instantiating a simpleCalc object as calc
def setUp(self):
self.calc = simpleCalc()
def runTest(self):
self.assertEqual(self.calc.subtract(7,3),4)
if __name__ == '__main__':
unittest.main()
I have been running the unit test file with the simple command:
testCalc.py
What I've attempted so far
First Attempt
I tried simply importing the simpleCalc object based on where it's located in the directory structure:
# testCalc.py
import unittest
from .calculatorAlgo.calculator import simpleCalc
class testCalc(unittest....
And got this error:
ValueError: Attempted relative import in non-package
Second Attempt
I tried importing it without relative references:
# testCalc.py
import unittest
import simpleCalc
class testCalc(unittest....
And got this error:
ImportError: No module named simpleCalc
Third Attempt
Based on this post, http://blog.aaronboman.com/programming/testing/2016/02/11/how-to-write-tests-in-python-project-structure/, I tried creating a separate base class called testcase.py which could do the relative imports.
# testcase.py
from unittest import TestCase
from ...calculator import simpleCalc
class BaseTestCase(TestCase):
pass
And changed my imports in testCalc.py
# testCalc.py
import unittest
from testlib.testcase import BaseTestCase
class testCalc(unittest....
And got this error:
ValueError: Attempted relative import beyond toplevel package
Other Resources
Here are some of the posts I've worked through to no avail:
Import a module from a relative path
python packaging for relative imports
How to fix "Attempted relative import in non-package" even with __init__.py
Python importing works from one folder but not another
Relative imports for the billionth time
Ultimately, I feel that I'm just missing something basic, even after a lot of research. This feels like a common setup, and I'm hoping someone can tell me what I'm doing wrong, and that it might help others avoid this problem in the future.
