How to write a test suite for nose

Question

If i want to write an unit test, I just drop a file in my test/ subdirectory with my test class heriting from unittest.TestCase.

Now i want to use such pattern for a test suite: I have a python file in test/ with a class (extending unittest.TestSuite) which reads a file and generate test from it. I've already the code for parsing the file and generate the TestCase from them.

But nose does not detect this class. How can I make nose aware of this file and generate the tests from it ?

Answer 1

You don't specify the version of python you are using. With Python 2.7+ you can define a load_tests function in your module which will be called to create the TestSuite for the module.

However, nose ignores the load_tests protocol. If you have nose2 then it features a plugin for the load tests protocol.

Otherwise, you create a blank TestCase and populate with generated test functions. For instance:

import unittest

data = ["a", "b", "c"] # or from whatever source you want

class GeneratedTests(unittest.TestCase):

    def setUp(self):
        self.correct = "b"

def setup_module():
    for i, d in enumerate(data):
        test_driver = create_driver(d)
        name ="test_generated{}".format(i)
        setattr(GeneratedTests, name, test_driver)

def create_driver(d):
    def test_driver(self):
        self.assertEqual(d, self.correct)
    return test_driver

setup_module()

One final way you can do this is to use the subtest context manager. This is only available in 3.4+. However, you can find a poor man's replacement here. Hopefully, it should help you structure your generated tests in a more readable fashion.