Rename expected error in tests for another specific error case

Author: saxbophone

basest/exceptions.py

@@ -2,9 +2,20 @@
 # -*- coding: utf-8 -*-
 
 
+class ImproperUsageError(ValueError):
+    """
+    This exception is raised when an attempt is made to encode data using a
+    larger output base than the input base AND when the length of the input
+    data is not exactly divisible by the input ratio.
+
+    This cannot be allowed because such options would cause data corruption.
+    """
+    pass
+
+
 class InvalidSymbolTableError(ValueError):
     """
-    This exception being raised indicates that the symbol table and/or padding
-    symbol supplied to an encoding/decoding operation are invalid.
+    This exception is raised when the symbol table and/or padding symbol
+    supplied to an encoding/decoding operation are invalid.
     """
     pass

tests/core/test_encode_decode_raw.py

@@ -9,6 +9,7 @@
 from ddt import data, ddt, unpack
 
 from basest.core import decode_raw, encode_raw
+from basest.exceptions import ImproperUsageError
 
 
 @ddt
@@ -80,9 +81,9 @@ def test_encode_raw_invalid_input_ratio(
         input ratio. This is because such an action normally can be solved with
         padding, however padding can only be used successfully on the 'smaller'
         side of the transformation, in any other case data corruption occurs.
-        If this is attempted, then ValueError should be raised.
+        If this is attempted, then ImproperUsageError should be raised.
         """
-        with self.assertRaises(ValueError):
+        with self.assertRaises(ImproperUsageError):
             encode_raw(
                 input_base=input_base, output_base=output_base,
                 input_ratio=input_ratio, output_ratio=output_ratio,