Correctly generate non-mod 1024 parts in generator

Also move implementation to utils and add unit tests.

s3tests/functional/utils.py

@@ -1,4 +1,6 @@
+import random
 import requests
+import string
 import time
 
 from nose.tools import eq_ as eq
@@ -18,6 +20,25 @@ def assert_raises(excClass, callableObj, *args, **kwargs):
             excName = str(excClass)
         raise AssertionError("%s not raised" % excName)
 
+def generate_random(size, part_size=5*1024*1024):
+    """
+    Generate the specified number random data.
+    (actually each MB is a repetition of the first KB)
+    """
+    chunk = 1024
+    allowed = string.ascii_letters
+    for x in range(0, size, part_size):
+        strpart = ''.join([allowed[random.randint(0, len(allowed) - 1)] for _ in xrange(chunk)])
+        s = ''
+        left = size - x
+        this_part_size = min(left, part_size)
+        for y in range(this_part_size / chunk):
+            s = s + strpart
+        s = s + strpart[:(this_part_size % chunk)]
+        yield s
+        if (x == size):
+            return
+
 # syncs all the regions except for the one passed in
 def region_sync_meta(targets, region):