Add packed recarray tests
diff --git a/example/example20.py b/example/example20.py
index d1bc942..0e42c68 100644
--- a/example/example20.py
+++ b/example/example20.py
@@ -2,23 +2,24 @@
 from __future__ import print_function
 
 import numpy as np
-from example import create_rec_simple
+from example import create_rec_simple, create_rec_packed
 
 
 def check_eq(arr, data, dtype):
     np.testing.assert_equal(arr, np.array(data, dtype=dtype))
 
-dtype = np.dtype({'names': ['x', 'y', 'z'],
-                  'formats': ['?', 'u4', 'f4'],
-                  'offsets': [0, 4, 8]})
-base_dtype = np.dtype([('x', '?'), ('y', 'u4'), ('z', 'f4')])
+simple_dtype = np.dtype({'names': ['x', 'y', 'z'],
+                         'formats': ['?', 'u4', 'f4'],
+                         'offsets': [0, 4, 8]})
+packed_dtype = np.dtype([('x', '?'), ('y', 'u4'), ('z', 'f4')])
 
-arr = create_rec_simple(3)
-assert arr.dtype == dtype
-check_eq(arr, [(False, 0, 0.0), (True, 1, 1.5), (False, 2, 3.0)], dtype)
-check_eq(arr, [(False, 0, 0.0), (True, 1, 1.5), (False, 2, 3.0)], base_dtype)
+for func, dtype in [(create_rec_simple, simple_dtype), (create_rec_packed, packed_dtype)]:
+    arr = func(3)
+    assert arr.dtype == dtype
+    check_eq(arr, [(False, 0, 0.0), (True, 1, 1.5), (False, 2, 3.0)], simple_dtype)
+    check_eq(arr, [(False, 0, 0.0), (True, 1, 1.5), (False, 2, 3.0)], packed_dtype)
 
-arr = create_rec_simple(0)
-assert arr.dtype == dtype
-check_eq(arr, [], dtype)
-check_eq(arr, [], base_dtype)
+    arr = func(0)
+    assert arr.dtype == dtype
+    check_eq(arr, [], simple_dtype)
+    check_eq(arr, [], packed_dtype)