fix tests

satella/random.py

@@ -13,14 +13,17 @@ def shuffle_together(*args: tp.Sequence) -> tp.List[tp.List]:
 
     >>> a = [1, 2, 3]
     >>> b = ['a', 'b', 'c']
-    >>> c = permute_together(a, b)
+    >>> c = shuffle_together(a, b)
 
     Might equal
 
     >>> c == [[3, 1, 2], ['c', 'a', 'b']]
-    """
 
-    indices = list(range(len(args[0])))
+    """
+    try:
+        indices = list(range(len(args[0])))
+    except IndexError:
+        return []  # empty array
 
     random.shuffle(indices)
-    return [[arg[i] for arg, i in zip(arg, indices)] for arg in args]
+    return [[arg[i] for i in indices] for arg in args]

tests/test_random.py

@@ -5,6 +5,9 @@ from satella.random import shuffle_together
 class TestRandom(unittest.TestCase):
     def test_random(self):
         a = [(1, 2, 3), ('a', 'b', 'c')]
-        b = zip(shuffle_together(*a))
+        b = zip(*shuffle_together(*a))
         self.assertEqual(set(b), {(1, 'a'), (2, 'b'), (3, 'c')})
 
+        self.assertEqual(shuffle_together(), [])
+
+