Expand the testing of invalid arguments

This is not significant advantage, but it does increase coverage. And
any coverage (even if not testing the logic too much) is better than
no coverage.

test/test_xattr.py

@@ -423,8 +423,24 @@ def testEmptyValue(self):
         xattr.set(fh, self.USER_ATTR, self.EMPTY_VAL)
         self.assertEqual(xattr.get(fh, self.USER_ATTR), self.EMPTY_VAL)
 
+    def testWrongCall(self):
+       for call in [xattr.get,
+                    xattr.list, xattr.listxattr,
+                    xattr.remove, xattr.removexattr,
+                    xattr.set, xattr.setxattr,
+                    xattr.get, xattr.getxattr]:
+           self.assertRaises(TypeError, call)
+
     def testWrongType(self):
         self.assertRaises(TypeError, xattr.get, object(), self.USER_ATTR)
+        for call in [xattr.listxattr, xattr.list]:
+            self.assertRaises(TypeError, call, object())
+        for call in [xattr.remove, xattr.removexattr,
+                     xattr.get, xattr.getxattr]:
+            self.assertRaises(TypeError, call, object(), self.USER_ATTR)
+        for call in [xattr.set, xattr.setxattr]:
+            self.assertRaises(TypeError, call, object(), self.USER_ATTR, self.USER_VAL)
+
 
     def testLargeAttribute(self):
         fh, fname = self._getfile()