2 files changed, 45 insertions, 0 deletions
diff --git a/numpy/core/src/multiarray/multiarray_tests.c.src b/numpy/core/src/multiarray/multiarray_tests.c.src
index f22b7462d..0aea85f66 100644
--- a/numpy/core/src/multiarray/multiarray_tests.c.src
+++ b/numpy/core/src/multiarray/multiarray_tests.c.src
@@ -557,6 +557,30 @@ fail:
 
     return NULL;
 }
+
+#if !defined(NPY_PY3K)
+static PyObject *
+int_subclass(PyObject *dummy, PyObject *args)
+{
+
+  PyObject *result = NULL;
+  PyObject *scalar_object = NULL;
+
+  if (!PyArg_UnpackTuple(args, "test_int_subclass", 1, 1, &scalar_object))
+    return NULL;
+
+  if (PyInt_Check(scalar_object))
+    result = Py_True;
+  else
+    result = Py_False;
+
+  Py_INCREF(result);
+
+  return result;
+
+}
+#endif
+
 static PyMethodDef Multiarray_TestsMethods[] = {
     {"test_neighborhood_iterator",
         test_neighborhood_iterator,
@@ -573,6 +597,11 @@ static PyMethodDef Multiarray_TestsMethods[] = {
     {"test_inplace_increment",
         inplace_increment,
         METH_VARARGS, NULL},
+#if !defined(NPY_PY3K)
+    {"test_int_subclass",
+        int_subclass,
+        METH_VARARGS, NULL},
+#endif
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 6cd24a76f..c298b4f1d 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -95,6 +95,22 @@ class TestAttributes(TestCase):
         assert_equal(self.one.dtype.str[1], 'i')
         assert_equal(self.three.dtype.str[1], 'f')
 
+    def test_int_subclassing(self):
+        # Regression test for https://github.com/numpy/numpy/pull/3526
+
+        numpy_int = np.int_(0)
+
+        if sys.version_info[0] >= 3:
+            # On Py3k int_ should not inherit from int, because it's not fixed-width anymore
+            assert_equal(isinstance(numpy_int, int), False)
+        else:
+            # Otherwise, it should inherit from int...
+            assert_equal(isinstance(numpy_int, int), True)
+
+            # ... and fast-path checks on C-API level should also work
+            from numpy.core.multiarray_tests import test_int_subclass
+            assert_equal(test_int_subclass(numpy_int), True)
+
     def test_stridesattr(self):
         x = self.one
         def make_array(size, offset, strides):