TestCase that unifies representations str/unicode and int/long

pretty_testcase.py

# -*- coding: utf-8 -*-
import pprint
import unittest


class PrettyDiffPrinter(pprint.PrettyPrinter):
    """A pprint subclass to hide some differences
    that usually don't matter in tests

    """
    _original_pformat = None

    def _repr(self, object, context, level):
        if isinstance(object, long):
            # If object is a long, don't represent it with a trailing 'L'
            # (unless it doesn't fit in a python int)
            object = int(object)
        elif isinstance(object, unicode):
            # If object is an unicode string, but ASCII only,
            # don't represent it with the leading 'u'
            try:
                object = object.encode('ascii')
            except UnicodeEncodeError:
                pass

        return pprint.PrettyPrinter._repr(self, object, context, level)

    def ppformat(self, object, *unused):
        # method  replacing the pprint.pformat static one during patch
        return self.pformat(object)

    def __enter__(self):
        self._original_pformat = pprint.pformat
        pprint.pformat = self.ppformat

    def __exit__(self, *unused):
        pprint.pformat = self._original_pformat


class PrettyTestCase(unittest.TestCase):
    _printer = PrettyDiffPrinter()

    def assertDictEqual(self, *args, **kwargs):
        with self._printer:
            return super(PrettyTestCase, self).assertDictEqual(*args, **kwargs)

    def assertSequenceEqual(self, *args, **kwargs):
        with self._printer:
            return super(PrettyTestCase, self) \
                .assertSequenceEqual(*args, **kwargs)


class DemoTest(PrettyTestCase):
    def test_fail_dict(self):
        # Expect, as defined by test creator
        expect = {'water': 3,
                  'base': u'café',
                  'fruits': {'oranges': 1, 'apples': 3},
                  'vegetables': {'carrots': 2, 'potatoes': 4},
                  }

        # Result, as actually returned by the library being tested
        result = {u'water': 3,
                  u'base': u'café',
                  u'fruits': {u'oranges': 1, u'apples': 3},
                  u'vegetables': {u'carrots': 2, u'potatoes': 5},
                  }

        self.assertEqual(result, expect)

    def test_fail_list(self):
        # Expect, as defined by test creator
        expect = [
            {'value': 1},
            {'value': 2},
            {'value': 3},
            {'value': 4},
            {'value': 5},
            {'value': 6}]

        # Result, as actually returned by the library being tested
        result = [
            {'value': 1L},
            {'value': 3L},
            {'value': 3L},
            {'value': 4L},
            {'value': 5L},
            {'value': 6L}]

        self.assertEqual(result, expect)


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

    
"""
======================================================================
FAIL: test_fail_dict (pretty_testcase.DemoTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "pretty_testcase.py", line 70, in test_fail_dict
    self.assertEqual(result, expect)
AssertionError: {u'water': 3, u'vegetables': {u'potatoes': 5, u'carrots': 2}, u'base': u'caf\xe9 [truncated]... != {'water': 3, 'vegetables': {'potatoes': 4, 'carrots': 2}, 'base': u'caf\xe9', 'f [truncated]...
  {'base': u'caf\xe9',
   'fruits': {'apples': 3, 'oranges': 1},
-  'vegetables': {'carrots': 2, 'potatoes': 5},
?                                           ^

+  'vegetables': {'carrots': 2, 'potatoes': 4},
?                                           ^

   'water': 3}

======================================================================
FAIL: test_fail_list (pretty_testcase.DemoTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "pretty_testcase.py", line 91, in test_fail_list
    self.assertEqual(result, expect)
AssertionError: Lists differ: [{'value': 1L}, {'value': 3L},... != [{'value': 1}, {'value': 2}, {...

First differing element 1:
{'value': 3L}
{'value': 2}

  [{'value': 1},
-  {'value': 3},
?            ^

+  {'value': 2},
?            ^

   {'value': 3},
   {'value': 4},
   {'value': 5},
   {'value': 6}]

----------------------------------------------------------------------
Ran 2 tests in 0.002s

FAILED (failures=2)

"""