Initial efforts for testing the proofofwork:

a test case, a test with data and python3 support.

src/tests/test_proofofwork.py

@@ -0,0 +1,36 @@
+"""
+Tests for proofofwork module
+"""
+
+import hashlib
+import unittest
+from binascii import unhexlify
+from struct import pack, unpack
+
+from pybitmessage import proofofwork
+
+
+class TestProofofwork(unittest.TestCase):
+    """The main test case for proofofwork"""
+
+    @classmethod
+    def setUpClass(cls):
+        proofofwork.init()
+
+    def test_empty(self):
+        """just reproducing the empty test from proofofwork.init()"""
+        self.assertEqual(
+            proofofwork._doCPoW(2**63, ""), [6485065370652060397, 4])
+
+    def test_with_target(self):
+        """Do PoW with parameters from test_openclpow and check the result"""
+        target = 54227212183
+        initialHash = unhexlify(
+            '3758f55b5a8d902fd3597e4ce6a2d3f23daff735f65d9698c270987f4e67ad590'
+            'b93f3ffeba0ef2fd08a8dc2f87b68ae5a0dc819ab57f22ad2c4c9c8618a43b3'
+        )
+        nonce = proofofwork._doCPoW(target, initialHash)[0]
+        trialValue, = unpack(
+            '>Q', hashlib.sha512(hashlib.sha512(
+                pack('>Q', nonce) + initialHash).digest()).digest()[0:8])
+        self.assertLess((nonce - trialValue), target)