Closes Bears-R-Us#3677: Occasional failures of test_string_broadcast (B…

…ears-R-Us#3678)

This PR fixes Bears-R-Us#3677 by regenerating `keys` if not all elements appear at least once

Co-authored-by: Tess Hayes <stress-tess@users.noreply.github.com>

tests/string_test.py

@@ -877,6 +877,10 @@ def test_inferred_type(self):
 
  def test_string_broadcast(self):
  keys = ak.randint(0, 10, 100, int)
+ while ak.unique(keys).size != 10:
+ # keep generating until every element appears at least once
+ keys = ak.randint(0, 10, 100, int)
+
  g = ak.GroupBy(keys)
  str_vals = ak.random_strings_uniform(0, 3, 10, characters="printable")
  str_broadcast_ans = str_vals[keys]