Add basic end-to-end signing and verification tests.

dkim/tests/data/test.message

@@ -0,0 +1,8 @@
+Received: from localhost
+Message-ID: <example@example.com>
+Date: Mon, 01 Jan 2011 01:02:03 +0400
+From: Test User <test@example.com>
+To: somebody@example.com
+Subject: Testing
+
+This is a test message.

dkim/tests/data/test.private

@@ -0,0 +1,15 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----

dkim/tests/data/test.txt

@@ -0,0 +1 @@
+v=DKIM1; g=*; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDkHlOQoBTzWRiGs5V6NpP3idY6Wk08a5qhdR6wy5bdOKb2jLQiY/J16JYi0Qvx/byYzCNb3W91y3FutACDfzwQ/BC/e/8uBsCR+yz1Lxj+PL6lHvqMKrM3rG4hstT5QjvHO9PzoxZyVYLzBfO2EeC3Ip3G+2kryOTIKT+l/K4w3QIDAQAB

dkim/tests/test_dkim.py

@@ -1,8 +1,18 @@
+import os.path
 import unittest
 
 import dkim
 
 
+def read_test_data(filename):
+    """Get the content of the given test data file.
+
+    The files live in dkim/tests/data.
+    """
+    path = os.path.join(os.path.dirname(__file__), 'data', filename)
+    return open(path).read()
+
+
 class TestFold(unittest.TestCase):
 
     def test_short_line(self):
@@ -16,5 +26,29 @@ class TestFold(unittest.TestCase):
             "foo"*24 + "\r\n foo", dkim.fold("foo" * 25))
 
 
+class TestSignAndVerify(unittest.TestCase):
+    """End-to-end signature and verification tests."""
+
+    def setUp(self):
+        self.message = read_test_data("test.message")
+        self.key = read_test_data("test.private")
+
+    def dnsfunc(self, domain):
+        self.assertEqual('test._domainkey.example.com.', domain)
+        return read_test_data("test.txt")
+
+    def test_verifies(self):
+        # A message verifies after being signed.
+        sig = dkim.sign(self.message, "test", "example.com", self.key)
+        res = dkim.verify(sig + self.message, dnsfunc=self.dnsfunc)
+        self.assertTrue(res)
+
+    def test_altered_body_fails(self):
+        # An altered body fails verification.
+        sig = dkim.sign(self.message, "test", "example.com", self.key)
+        res = dkim.verify(sig + self.message + "foo", dnsfunc=self.dnsfunc)
+        self.assertFalse(res)
+
+
 if __name__ == '__main__':
     unittest.main()