import sys
import unittest
from dynd import nd, ndt

class TestGroupBy(unittest.TestCase):
    def test_immutable(self):
        a = nd.ndobject([
                ('x', 0),
                ('y', 1),
                ('x', 2),
                ('x', 3),
                ('y', 4)],
                udtype='{A: string; B: int32}').eval_immutable()
        gb = nd.groupby(a, nd.fields(a, 'A'))
        self.assertEqual(nd.as_py(gb.groups), [{'A': 'x'}, {'A': 'y'}])
        self.assertEqual(nd.as_py(gb), [
                [{'A': 'x', 'B': 0},
                 {'A': 'x', 'B': 2},
                 {'A': 'x', 'B': 3}],
                [{'A': 'y', 'B': 1},
                 {'A': 'y', 'B': 4}]])

if __name__ == '__main__':
    unittest.main()

Add test of groupby with immutable 'by'
Add test of groupby with immutable 'by'
