BUG: Add missing check for 0-sized array in ravel_multi_index

In wrap and clip modes ravel_multi_index crashes or gave
invalid results if input arrays were empty but the shape not.

1 files changed, 18 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_index_tricks.py b/numpy/lib/tests/test_index_tricks.py
index a5cdda074..dbe445c2c 100644
--- a/numpy/lib/tests/test_index_tricks.py
+++ b/numpy/lib/tests/test_index_tricks.py
@@ -175,6 +175,24 @@ class TestRavelUnravelIndex(object):
         assert_raises_regex(
             ValueError, "out of bounds", np.unravel_index, [1], ())
 
+    @pytest.mark.parametrize("mode", ["clip", "wrap", "raise"])
+    def test_empty_array_ravel(self, mode):
+        res = np.ravel_multi_index(
+                    np.zeros((3, 0), dtype=np.intp), (2, 1, 0), mode=mode)
+        assert(res.shape == (0,))
+
+        with assert_raises(ValueError):
+            np.ravel_multi_index(
+                    np.zeros((3, 1), dtype=np.intp), (2, 1, 0), mode=mode)
+
+    def test_empty_array_unravel(self):
+        res = np.unravel_index(np.zeros(0, dtype=np.intp), (2, 1, 0))
+        # res is a tuple of three empty arrays
+        assert(len(res) == 3)
+        assert(all(a.shape == (0,) for a in res))
+
+        with assert_raises(ValueError):
+            np.unravel_index([1], (2, 1, 0))
 
 class TestGrid(object):
     def test_basic(self):