diff --git a/tests/test_transform.py b/tests/test_transform.py
new file mode 100644
index 0000000..ecc1a30
--- /dev/null
+++ b/tests/test_transform.py
@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+
+
+import unittest2
+from rsa._compat import b
+from rsa.transform import int2bytes
+
+
+class Test_integer_to_bytes(unittest2.TestCase):
+    def test_chunk_size(self):
+        self.assertEqual(int2bytes(123456789, 6),
+                         b('\x00\x00\x07[\xcd\x15'))
+        self.assertEqual(int2bytes(123456789, 7),
+                         b('\x00\x00\x00\x07[\xcd\x15'))
+
+    def test_raises_OverflowError_when_chunk_size_is_insufficient(self):
+        self.assertRaises(OverflowError, int2bytes, 123456789, 3)
+        self.assertRaises(OverflowError, int2bytes, 299999999999, 4)
+
+    def test_raises_ValueError_when_negative_integer(self):
+        self.assertRaises(ValueError, int2bytes, -1)
+
+    def test_raises_TypeError_when_not_integer(self):
+        self.assertRaises(TypeError, int2bytes, None)