Test float cast in _norm_args (#105)

Provide integral data to `_norm_args` to test that it does cast this to
float.

tests/test_dask_image/test_ndfourier/test__utils.py

@@ -1,6 +1,8 @@
 # -*- coding: utf-8 -*-
 
 
+import numbers
+
 import pytest
 
 import dask.array as da
@@ -11,6 +13,8 @@
 @pytest.mark.parametrize(
     "a, s, n, axis", [
         (da.ones((3, 4), chunks=(3, 4)), da.ones((2,), chunks=(2,)), -1, -1),
+        (da.ones((3, 4), dtype='i8', chunks=(3, 4)),
+         da.ones((2,), dtype='i8', chunks=(2,)), -1, -1),
     ]
 )
 def test_norm_args(a, s, n, axis):
@@ -20,3 +24,6 @@ def test_norm_args(a, s, n, axis):
 
     assert isinstance(a2, da.Array)
     assert isinstance(s2, da.Array)
+
+    assert issubclass(a2.real.dtype.type, numbers.Real)
+    assert issubclass(s2.dtype.type, numbers.Real)