def test_out(self, array):
x = array(self.x)
x_dtype = x.dtype
result = isnan(x, out=x)
self.assertIs(result, x)
self.assertEqual(x_dtype, result.dtype)
def test_functionality(self, array):
expected = np.isnan(self.x)
result = isnan(array(self.x))
np.testing.assert_equal(assure_array_dense(result), expected)