BUG: Allow `unravel_index(0, ())` to return ()

Fixes gh-580

1 files changed, 12 insertions, 1 deletions

diff --git a/numpy/lib/tests/test_index_tricks.py b/numpy/lib/tests/test_index_tricks.py
index 452b3d6a2..1d5efef86 100644
--- a/numpy/lib/tests/test_index_tricks.py
+++ b/numpy/lib/tests/test_index_tricks.py
@@ -3,7 +3,8 @@ from __future__ import division, absolute_import, print_function
 import numpy as np
 from numpy.testing import (
     run_module_suite, assert_, assert_equal, assert_array_equal,
-    assert_almost_equal, assert_array_almost_equal, assert_raises
+    assert_almost_equal, assert_array_almost_equal, assert_raises,
+    assert_raises_regex
     )
 from numpy.lib.index_tricks import (
     mgrid, ndenumerate, fill_diagonal, diag_indices, diag_indices_from,
@@ -114,6 +115,16 @@ class TestRavelUnravelIndex(object):
         assert_(y.flags.writeable)
 
 
+    def test_0d(self):
+        # gh-580
+        x = np.unravel_index(0, ())
+        assert_equal(x, ())
+
+        assert_raises_regex(ValueError, "0d array", np.unravel_index, [0], ())
+        assert_raises_regex(
+            ValueError, "out of bounds", np.unravel_index, [1], ())
+
+
 class TestGrid(object):
     def test_basic(self):
         a = mgrid[-1:1:10j]