TST: np.kron tests refinement

* Added `mat` cases to smoke tests
* Changed type checks to handle new change which uses ufuncs order for
  result determination
* Added cases for `ma` to check subclass info retention

Author: ganesh-k13

numpy/lib/tests/test_shape_base.py

@@ -646,21 +646,31 @@ def test_basic(self):
 class TestKron:
     def test_return_type(self):
         class myarray(np.ndarray):
-            __array_priority__ = 0.0
+            __array_priority__ = 1.0
 
         a = np.ones([2, 2])
         ma = myarray(a.shape, a.dtype, a.data)
         assert_equal(type(kron(a, a)), np.ndarray)
         assert_equal(type(kron(ma, ma)), myarray)
-        assert_equal(type(kron(a, ma)), np.ndarray)
+        assert_equal(type(kron(a, ma)), myarray)
         assert_equal(type(kron(ma, a)), myarray)
 
-    def test_kron_smoke(self):
-        a = np.ones([3, 3])
-        b = np.ones([3, 3])
-        k = np.ones([9, 9])
+    @pytest.mark.parametrize(
+        "array_class", [np.asarray, np.mat]
+    )
+    def test_kron_smoke(self, array_class):
+        a = array_class(np.ones([3, 3]))
+        b = array_class(np.ones([3, 3]))
+        k = array_class(np.ones([9, 9]))
+
+        assert_array_equal(np.kron(a, b), k)
+
+    def test_kron_ma(self):
+        x = np.ma.array([[1, 2], [3, 4]], mask=[[0, 1], [1, 0]])
+        k = np.ma.array(np.diag([1, 4, 4, 16]),
+                mask=~np.array(np.identity(4), dtype=bool))
 
-        assert np.array_equal(np.kron(a, b), k), "Smoke test for kron failed"
+        assert_array_equal(k, np.kron(x, x))
 
     @pytest.mark.parametrize(
         "shape_a,shape_b", [