def test_combinatorics(self):
        # Test relationships between product(), permutations(),
        # combinations() and combinations_with_replacement().

        for n in range(6):
            s = 'ABCDEFG'[:n]
            for r in range(8):
                prod = list(product(s, repeat=r))
                cwr = list(combinations_with_replacement(s, r))
                perm = list(permutations(s, r))
                comb = list(combinations(s, r))

                # Check size
                self.assertEqual(len(prod), n**r)
                self.assertEqual(len(cwr), (fact(n+r-1) / fact(n-1)/ fact(r)) if n else (not r))
                self.assertEqual(len(perm), 0 if r>n else fact(n) / fact(n-r))
                self.assertEqual(len(comb), 0 if r>n else fact(n) / fact(r) / fact(n-r))

                # Check lexicographic order without repeated tuples
                self.assertEqual(prod, sorted(set(prod)))
                self.assertEqual(cwr, sorted(set(cwr)))
                self.assertEqual(perm, sorted(set(perm)))
                self.assertEqual(comb, sorted(set(comb)))

                # Check interrelationships
                self.assertEqual(cwr, [t for t in prod if sorted(t)==list(t)]) # cwr: prods which are sorted
                self.assertEqual(perm, [t for t in prod if len(set(t))==r])    # perm: prods with no dups
                self.assertEqual(comb, [t for t in perm if sorted(t)==list(t)]) # comb: perms that are sorted
                self.assertEqual(comb, [t for t in cwr if len(set(t))==r])      # comb: cwrs without dups
                self.assertEqual(comb, list(filter(set(cwr).__contains__, perm)))     # comb: perm that is a cwr
                self.assertEqual(comb, list(filter(set(perm).__contains__, cwr)))     # comb: cwr that is a perm
                self.assertEqual(comb, sorted(set(cwr) & set(perm)))            # comb: both a cwr and a perm
dataset/ETHPy150Open amrdraz/kodr/app/brython/www/src/Lib/test/test_itertools.py/TestBasicOps.test_combinatorics/swapped operands of `/`