Fix/test cases with pytest (#275)

* fixed test_sycl_usm to with both pytest and unittests

Co-authored-by: Oleksandr Pavlyk <oleksandr.pavlyk@intel.com>

Author: diptorupd

dpctl/tests/test_sycl_usm.py

@@ -164,11 +164,11 @@ def test_pickling(self):
         )
 
 
-class TestMemoryUSMBase:
+class _TestMemoryUSMBase:
     """ Base tests for MemoryUSM* """
 
-    MemoryUSMClass = None
-    usm_type = None
+    def setUp(self):
+        pass
 
     @unittest.skipUnless(
         dpctl.has_sycl_platforms(), "No SYCL devices except the default host device."
@@ -217,25 +217,28 @@ def test_sycl_usm_array_interface(self):
         self.assertTrue(np.array_equal(m.copy_to_host(), hb))
 
 
-class TestMemoryUSMShared(TestMemoryUSMBase, unittest.TestCase):
+class TestMemoryUSMShared(_TestMemoryUSMBase, unittest.TestCase):
     """ Tests for MemoryUSMShared """
 
-    MemoryUSMClass = MemoryUSMShared
-    usm_type = "shared"
+    def setUp(self):
+        self.MemoryUSMClass = MemoryUSMShared
+        self.usm_type = "shared"
 
 
-class TestMemoryUSMHost(TestMemoryUSMBase, unittest.TestCase):
+class TestMemoryUSMHost(_TestMemoryUSMBase, unittest.TestCase):
     """ Tests for MemoryUSMHost """
 
-    MemoryUSMClass = MemoryUSMHost
-    usm_type = "host"
+    def setUp(self):
+        self.MemoryUSMClass = MemoryUSMHost
+        self.usm_type = "host"
 
 
-class TestMemoryUSMDevice(TestMemoryUSMBase, unittest.TestCase):
+class TestMemoryUSMDevice(_TestMemoryUSMBase, unittest.TestCase):
     """ Tests for MemoryUSMDevice """
 
-    MemoryUSMClass = MemoryUSMDevice
-    usm_type = "device"
+    def setUp(self):
+        self.MemoryUSMClass = MemoryUSMDevice
+        self.usm_type = "device"
 
 
 if __name__ == "__main__":