shuffle alphabet and ensure min length of 3 chars

shortener/api.py

@@ -1,4 +1,5 @@
 # -*- test-case-name: shortener.tests.test_api -*-
+import random
 import string
 from urlparse import urljoin, urlparse
 
@@ -11,6 +12,8 @@
 from shortener.models import ShortenerTables, NoShortenerTables
 
 DEFAULT_ALPHABET = string.digits + string.ascii_letters
+SHORT_URL_OFFSET = 4000
+
 DEFAULT_USER_TOKEN = 'generic-user-token'
 
 
@@ -100,12 +103,17 @@ def update_short_url(self, row_id, short_url):
         finally:
             yield conn.close()
 
+    def shuffle_string(self, str):
+        shuffle = lambda seq: random.Random(1234).sample(seq, len(seq))
+        return ''.join(shuffle(list(str)))
+
     def generate_token(self, counter, alphabet=DEFAULT_ALPHABET):
         if not isinstance(counter, int):
             raise TypeError('an integer is required')
+
+        alphabet = self.shuffle_string(alphabet)
         base = len(alphabet)
-        if counter == 0:
-            return alphabet[0]
+        counter += SHORT_URL_OFFSET
 
         digits = []
         while counter > 0:

shortener/tests/test_api.py

@@ -61,7 +61,7 @@ def test_create_url_simple(self):
             pool=self.pool)
 
         result = yield treq.json_content(resp)
-        self.assertEqual(result['short_url'], 'http://wtxt.io/1')
+        self.assertEqual(result['short_url'], 'http://wtxt.io/q0r')
 
     @inlineCallbacks
     def test_create_url_no_user_token(self):
@@ -75,15 +75,15 @@ def test_create_url_no_user_token(self):
             pool=self.pool)
 
         result = yield treq.json_content(resp)
-        self.assertEqual(result['short_url'], 'http://wtxt.io/1')
+        self.assertEqual(result['short_url'], 'http://wtxt.io/q0r')
 
     @inlineCallbacks
     def test_resolve_url_simple(self):
         url = 'http://en.wikipedia.org/wiki/Cthulhu'
         yield self.service.shorten_url(url)
 
         resp = yield treq.get(
-            self.make_url('/1'),
+            self.make_url('/q0r'),
             allow_redirects=False,
             pool=self.pool)
 
@@ -107,7 +107,7 @@ def test_resolve_url_404(self):
     def test_url_shortening(self):
         long_url = 'http://en.wikipedia.org/wiki/Cthulhu'
         short_url = yield self.service.shorten_url(long_url)
-        self.assertEqual(short_url, 'http://wtxt.io/1')
+        self.assertEqual(short_url, 'http://wtxt.io/q0r')
 
     @inlineCallbacks
     def test_short_url_generation(self):
@@ -137,7 +137,7 @@ def test_resolve_url(self):
         yield self.service.shorten_url(url + '3')
         yield self.service.shorten_url(url + '4')
 
-        result = yield self.service.get_row_by_short_url('4')
+        result = yield self.service.get_row_by_short_url('q0H')
         self.assertEqual(result['long_url'], url + '4')
 
     @inlineCallbacks
@@ -147,8 +147,8 @@ def test_short_url_sequencing(self):
         for u in urls:
             yield self.service.shorten_url(u)
 
-        result = yield self.service.get_row_by_short_url('1p')
-        self.assertEqual(result['long_url'], url + '87')
+        result = yield self.service.get_row_by_short_url('qR1')
+        self.assertEqual(result['long_url'], url + '40')
 
-        result = yield self.service.get_row_by_short_url('1b')
-        self.assertEqual(result['long_url'], url + '73')
+        result = yield self.service.get_row_by_short_url('qR3')
+        self.assertEqual(result['long_url'], url + '55')