Method assertSetEqual

Lib/unittest/case.py:1144–1185

A set-specific equality assertion. Args: set1: The first set to compare. set2: The second set to compare. msg: Optional message to use on failure instead of a list of differences. assertSetEqual uses ducktyping to support diff

(self, set1, set2, msg=None)

        self.assertSequenceEqual(tuple1, tuple2, msg, seq_type=tuple)

    def assertSetEqual(self, set1, set2, msg=None):
        """A set-specific equality assertion.

        Args:
            set1: The first set to compare.
            set2: The second set to compare.
            msg: Optional message to use on failure instead of a list of
                    differences.

        assertSetEqual uses ducktyping to support different types of sets, and
        is optimized for sets specifically (parameters must support a
        difference method).
        """
        try:
            difference1 = set1.difference(set2)
        except TypeError as e:
            self.fail('invalid type when attempting set difference: %s' % e)
        except AttributeError as e:
            self.fail('first argument does not support set difference: %s' % e)

        try:
            difference2 = set2.difference(set1)
        except TypeError as e:
            self.fail('invalid type when attempting set difference: %s' % e)
        except AttributeError as e:
            self.fail('second argument does not support set difference: %s' % e)

        if not (difference1 or difference2):
            return

        lines = []
        if difference1:
            lines.append('Items in the first set but not the second:')
            for item in difference1:
                lines.append(repr(item))
        if difference2:
            lines.append('Items in the second set but not the first:')
            for item in difference2:
                lines.append(repr(item))

        standardMsg = '\n'.join(lines)
        self.fail(self._formatMessage(msg, standardMsg))

    def assertIn(self, member, container, msg=None):
        """Just like self.assertTrue(a in b), but with a nicer default message."""