diff --git a/src/cryptobox/tests/test.cryptoboxtools.py b/src/cryptobox/tests/test.core.blockdevice.py
similarity index 65%
rename from src/cryptobox/tests/test.cryptoboxtools.py
rename to src/cryptobox/tests/test.core.blockdevice.py
index 0a03a85..003273b 100755
--- a/src/cryptobox/tests/test.cryptoboxtools.py
+++ b/src/cryptobox/tests/test.core.blockdevice.py
@@ -25,44 +25,36 @@
 __revision__ = "$Id$"
 
 
-import cryptobox.core.tools as cbx_tools
+import cryptobox.core.blockdevice as blockdevice
 from cryptobox.tests.base import CommonTestClass
+from cryptobox.core.exceptions import CBInternalError
 import os
 
 
-class CryptoBoxToolsTests(CommonTestClass):
+class CoreBlockDevice(CommonTestClass):
     """All unittests for cryptoboxtools
     """
 
     def test_find_major_minor_of_device(self):
         """check the find_major_minor_of_device function
         """
-        func = cbx_tools.find_major_minor_of_device
-        self.assertTrue(func(os.path.devnull) == (1, 3))
+        func = blockdevice.get_blockdevice
+        self.assertTrue(func('/dev/ram0').devnum == (1, 0))
         self.assertTrue(func("/dev/nothere") is None)
 
 
-    def test_find_major_minor_device(self):
-        """check the find_major_minor_device function
-        """
-        func = cbx_tools.find_major_minor_device
-        path = os.path.join(os.path.sep, "dev")
-        self.assertTrue(os.path.devnull in func(path, 1, 3))
-        self.assertFalse(os.path.devnull in func(path, 2, 3))
-        self.assertFalse(None in func(path, 17, 23))
-
-
     def test_is_part_of_blockdevice(self):
         """check the is_part_of_blockdevice function
         """
-        func = cbx_tools.is_part_of_blockdevice
+        get_device = lambda devname: blockdevice.get_blockdevice(devname)
+        func = lambda parent, child: get_device(parent).is_parent_of(get_device(child))
+        func_raw = lambda parent: get_device(parent).is_parent_of
         self.assertTrue(func(self.blockdevice, self.device))
         self.assertFalse(func(self.blockdevice, self.blockdevice))
         self.assertFalse(func(self.device, self.blockdevice))
         self.assertFalse(func(self.device, self.device))
         self.assertFalse(func(self.blockdevice, "/dev/hde1"))
-        self.assertFalse(func(None, self.blockdevice))
-        self.assertFalse(func(self.blockdevice, None))
-        self.assertFalse(func(None, ""))
-        self.assertFalse(func("loop0", "loop1"))
+        self.assertFalse(func("ram0", "ram1"))
+        self.assertFalse(func_raw(self.blockdevice), None))
+        self.assertRaises(CBInternalError, func_raw(self.blockdevice), "")