AttributeError: '...' object has no attribute '_type_equality_funcs'

Question

I'm trying to use Python's unittest module to compare results and expected values and get test statistics in the end. However, below sample code gives me the following error:

File "...", line 16, in <module>
  run_tests.test_equal()
File "...", line 13, in test_equal
  self.assertEqual(self.result, self.expected)
File "/usr/lib/python2.7/unittest/case.py", line 512, in assertEqual
  assertion_func = self._getAssertEqualityFunc(first, second)
File "/usr/lib/python2.7/unittest/case.py", line 493, in _getAssertEqualityFunc
  asserter = self._type_equality_funcs.get(type(first))
AttributeError: 'RunTests' object has no attribute '_type_equality_funcs'

Sample code:

import unittest

class RunTests(unittest.TestCase):
   def __init__(self, result, expected):
      self.result = result
      self.expected = expected

   def runTest(self):
      test_equal(self)

   def test_equal(self):
      self.assertEqual(self.result, self.expected)

run_tests = RunTests(9, 9)
run_tests.test_equal()

if __name__ == '__main__':
   unittest.main()

How can I use the module's comparison functions on varying input values? I have found this post, but the problem appears to be different.

Thanks a lot in advance.

Andrew_Lvov · Accepted Answer · 2018-09-17 14:10:10Z

4

You skipped the call of __init__ of a base class inside your RunTests.__init__, which takes care of defining _type_equality_funcs.

def __init__(self, result, expected):
      super().__init__()
      self.result = result
      self.expected = expected

answered Sep 17, 2018 at 14:10

Andrew_Lvov

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4 Comments

canavanin Over a year ago

If I make the change you suggest I get the error "TypeError: super() takes at least 1 argument (0 given)" Googling it tells me that this is a Python 3 functionality, but I am using Python 2.7.12, and I cannot install any new modules/upgrade the Python version.

Andrew_Lvov Over a year ago

C'mon. super(subClass, instance).method(args) In your case: super(RunTests, self).__init__()

canavanin Over a year ago

Sorry for the noob-question, but I haven't used Python and OO programming in ages. Now all I get is "TypeError: __init__() takes exactly 3 arguments (2 given) " -.-

Andrew_Lvov Over a year ago

unittest framework expects that your class that inherit from TestCase` have a single-argument __init__ method which accepts methodName. So you should follow this interface. So you have to pass values somehow differently

Rahul Raut · Accepted Answer · 2018-09-17 14:31:40Z

2

you need to call __init__ method of base class. this might be useful :

    import unittest
    class RunTests(unittest.TestCase):
       def __init__(self, *args, **kwargs):
          super(RunTests, self).__init__()

       def runTest(self):
          self.test_equal()

       def test_equal(self):
          self.assertEqual(9, 9)

    run_tests = RunTests()
    run_tests.test_equal()

    if __name__ == '__main__':
       unittest.main()

answered Sep 17, 2018 at 14:31

Rahul Raut

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