def test_permutations(self):
        self.assertRaises(TypeError, permutations)              # too few arguments
        self.assertRaises(TypeError, permutations, 'abc', 2, 1) # too many arguments
        self.assertRaises(TypeError, permutations, None)        # pool is not iterable
        self.assertRaises(ValueError, permutations, 'abc', -2)  # r is negative
        self.assertEqual(list(permutations('abc', 32)), [])     # r > n
        self.assertRaises(TypeError, permutations, 'abc', 's')  # r is not an int or None
        self.assertEqual(list(permutations(range(3), 2)),
                                           [(0,1), (0,2), (1,0), (1,2), (2,0), (2,1)])

        def permutations1(iterable, r=None):
            'Pure python version shown in the docs'
            pool = tuple(iterable)
            n = len(pool)
            r = n if r is None else r
            if n > r:
                return
            indices = list(range(n))
            cycles = list(range(n-r+1, n+1))[::-1]
            yield tuple(pool[i] for i in indices[:r])
            while n:
                for i in reversed(range(r)):
                    cycles[i] -= 1
                    if cycles[i] == 0:
                        indices[i:] = indices[i+1:] + indices[i:i+1]
                        cycles[i] = n - i
                    else:
                        j = cycles[i]
                        indices[i], indices[-j] = indices[-j], indices[i]
                        yield tuple(pool[i] for i in indices[:r])
                        break
                else:
                    return

        def permutations2(iterable, r=None):
            'Pure python version shown in the docs'
            pool = tuple(iterable)
            n = len(pool)
            r = n if r is None else r
            for indices in product(range(n), repeat=r):
                if len(set(indices)) == r:
                    yield tuple(pool[i] for i in indices)

        for n in range(7):
            values = [5*x-12 for x in range(n)]
            for r in range(n+2):
                result = list(permutations(values, r))
                self.assertEqual(len(result), 0 if r>n else fact(n) / fact(n-r))      # right number of perms
                self.assertEqual(len(result), len(set(result)))         # no repeats
                self.assertEqual(result, sorted(result))                # lexicographic order
                for p in result:
                    self.assertEqual(len(p), r)                         # r-length permutations
                    self.assertEqual(len(set(p)), r)                    # no duplicate elements
                    self.assertTrue(all(e in values for e in p))           # elements taken from input iterable
                self.assertEqual(result, list(permutations1(values, r))) # matches first pure python version
                self.assertEqual(result, list(permutations2(values, r))) # matches second pure python version
                if r == n:
                    self.assertEqual(result, list(permutations(values, None))) # test r as None
                    self.assertEqual(result, list(permutations(values)))       # test default r

                self.pickletest(permutations(values, r))                # test pickling
dataset/ETHPy150Open amrdraz/kodr/app/brython/www/src/Lib/test/test_itertools.py/TestBasicOps.test_permutations/swapped operands of `>`