Made hashing efficient for large files
diff --git a/tests/test_varblock.py b/tests/test_varblock.py
new file mode 100644
index 0000000..d8addb4
--- /dev/null
+++ b/tests/test_varblock.py
@@ -0,0 +1,77 @@
+'''Tests varblock operations.'''
+
+from StringIO import StringIO
+import unittest
+
+import rsa
+from rsa import varblock
+
+class VarintTest(unittest.TestCase):
+
+    def test_read_varint(self):
+        
+        encoded = '\xac\x02crummy'
+        infile = StringIO(encoded)
+
+        (decoded, read) = varblock.read_varint(infile)
+
+        # Test the returned values
+        self.assertEqual(300, decoded)
+        self.assertEqual(2, read)
+
+        # The rest of the file should be untouched
+        self.assertEqual('crummy', infile.read())
+
+    def test_read_zero(self):
+        
+        encoded = '\x00crummy'
+        infile = StringIO(encoded)
+
+        (decoded, read) = varblock.read_varint(infile)
+
+        # Test the returned values
+        self.assertEqual(0, decoded)
+        self.assertEqual(1, read)
+
+        # The rest of the file should be untouched
+        self.assertEqual('crummy', infile.read())
+
+    def test_write_varint(self):
+        
+        expected = '\xac\x02'
+        outfile = StringIO()
+
+        written = varblock.write_varint(outfile, 300)
+
+        # Test the returned values
+        self.assertEqual(expected, outfile.getvalue())
+        self.assertEqual(2, written)
+
+
+    def test_write_zero(self):
+        
+        outfile = StringIO()
+        written = varblock.write_varint(outfile, 0)
+
+        # Test the returned values
+        self.assertEqual('\x00', outfile.getvalue())
+        self.assertEqual(1, written)
+
+
+class VarblockTest(unittest.TestCase):
+
+    def test_yield_varblock(self):
+        infile = StringIO('\x01\x0512345\x06Sybren')
+
+        varblocks = list(varblock.yield_varblocks(infile))
+        self.assertEqual(['12345', 'Sybren'], varblocks)
+
+class FixedblockTest(unittest.TestCase):
+
+    def test_yield_fixedblock(self):
+
+        infile = StringIO('123456Sybren')
+
+        fixedblocks = list(varblock.yield_fixedblocks(infile, 6))
+        self.assertEqual(['123456', 'Sybren'], fixedblocks)
+