MAINT: improve coverage of slow path by using a user-defined dtype

1 files changed, 9 insertions, 2 deletions

diff --git a/numpy/core/tests/test_ufunc.py b/numpy/core/tests/test_ufunc.py
index 00aa48647..b228c441c 100644
--- a/numpy/core/tests/test_ufunc.py
+++ b/numpy/core/tests/test_ufunc.py
@@ -1923,12 +1923,19 @@ class TestUfunc:
         assert_(MyThing.rmul_count == 1, MyThing.rmul_count)
         assert_(MyThing.getitem_count <= 2, MyThing.getitem_count)
 
-    def test_inplace_fancy_indexing(self):
+    @pytest.mark.parametrize("a", (
+                             np.arange(10, dtype=int),
+                             np.arange(10, dtype=_rational_tests.rational),
 
-        a = np.arange(10)
+    ))
+    def test_inplace_fancy_indexing(self, a):
         np.add.at(a, [2, 5, 2], 1)
         assert_equal(a, [0, 1, 4, 3, 4, 6, 6, 7, 8, 9])
 
+        np.negative.at(a, [2, 5, 3])
+        assert_equal(a, [0, 1, -4, -3, 4, -6, 6, 7, 8, 9])
+
+        # reset a
         a = np.arange(10)
         b = np.array([100, 100, 100])
         np.add.at(a, [2, 5, 2], b)