replacing magic numbers with consts, opting for list-based rather than string-based stuff in most places

onetimepad.py

@@ -1,5 +1,10 @@
 import random
 
+PAD_MODULO = 3
+DEFAULT_PAD_WIDTH = 72
+CIPHER_FLOOR = 1
+CIPHER_CEIL = 25
+
 
 def encode(msg, pad):
     return msg
@@ -9,27 +14,34 @@ def decode(msg, pad):
     return msg
 
 
-def create_pad(length, width=72):
+def create_pad(length, width=DEFAULT_PAD_WIDTH):
+    return '\n'.join(create_pad_lines(length, width=width))
+
+
+def create_pad_lines(length, width=DEFAULT_PAD_WIDTH):
     chars = _create_chars_for_pad(length)
     lines = _chunk_chars_into_lines(chars, width=width)
-    return '\n\n\n'.join(lines)
+    for line in lines:
+        yield line
+        yield ''
+        yield ''
 
 
 def _create_chars_for_pad(length):
     chars = []
     for char in range(length):
-        chars.append(_AS_ALPHA[random.randint(1, 25)])
+        chars.append(_AS_ALPHA[random.randint(CIPHER_FLOOR, CIPHER_CEIL)])
     return ''.join(chars)
 
 
-def _chunk_chars_into_lines(chars, width=72):
+def _chunk_chars_into_lines(chars, width=DEFAULT_PAD_WIDTH):
     lines = []
     for chunk in _as_line_chunks(chars, width=width):
         lines.append(chunk)
     return lines
 
 
-def _as_line_chunks(chars, width=72):
+def _as_line_chunks(chars, width=DEFAULT_PAD_WIDTH):
     chunk = []
     for char in chars:
         chunk.append(char)
@@ -57,11 +69,11 @@ def _get_textwidth(text):
 
 
 def _is_padline(lineno):
-    return not lineno % 3
+    return not lineno % PAD_MODULO
 
 
 def _is_txtline(lineno):
-    return (lineno % 2 and not lineno % 3)
+    return (lineno % 2 and not lineno % PAD_MODULO)
 
 
 def _is_cipherline(lineno):
@@ -73,7 +85,7 @@ def _mk_as_alpha():
     a_chr = ord('A')
     past_j = False
 
-    for char in range(26):
+    for char in range(CIPHER_CEIL + 1):
         letter = chr(a_chr + char)
         if letter != 'J':
             key = char + (1 if not past_j else 0)

test_onetimepad.py

@@ -5,6 +5,7 @@ import onetimepad as OT
 class TestOneTimePad(unittest.TestCase):
     msg = ('HOWMUCHCHUCKCOULDAWOODCHUCKCHUCKIFA'
            'WOODCHUCKCOULDCHUCKWOOD' * 50)
+    _padsize = 2000
 
     def test_mk_as_alpha_excludes_j(self):
         self.assertTrue('J' not in OT._AS_ALPHA.values())
@@ -14,13 +15,17 @@ class TestOneTimePad(unittest.TestCase):
 
     def test_creates_pad_of_desired_length(self):
         for width in (72, 33, 99, 111):
-            pad = OT.create_pad(2000, width=width)
-            lines = [line.strip('.') for line in pad.split('\n\n\n')]
-            self.assertEqual(2000, len(''.join(lines)))
+            pad = OT.create_pad(self._padsize, width=width)
+            lines = [line.strip('.') for line in pad.split()]
+            actual = len(''.join(lines))
+            self.assertEqual(self._padsize, len(''.join(lines)),
+                             'pad of {0} chars created at width '
+                             '{1}, actual={2}'.format(self._padsize,
+                                                      width, actual))
 
     def test_two_out_of_every_three_lines_are_empty_on_new_pad(self):
-        pad = OT.create_pad(2000)
-        for lineno, line in enumerate(pad.splitlines()):
+        pad = OT.create_pad_lines(2000)
+        for lineno, line in enumerate(pad):
             line = line.strip()
             if OT._is_padline(lineno):
                 self.assertTrue(bool(len(line)),