basic test for whether message splitting works

Hash2Pub/src/Hash2Pub/ASN1Coding.hs

@@ -22,7 +22,7 @@ import Hash2Pub.DHTProtocol
 
 import Debug.Trace
 
--- TODO: make this splitting function more intelligent, currently it creates many parts that are smaller than they could be
+-- TODO: make this splitting function more intelligent, currently it creates many parts that are smaller than they could be, see #18
 -- | Try splitting a payload into multiple parts to be able to reduce size of
 -- individual messages.
 -- Only some kinds of payloads can be split, and only to a limited number of parts.

Hash2Pub/test/FediChordSpec.hs

@@ -228,8 +228,17 @@ spec = do
             encodeDecodeAndCheck $ responseWith Leave lResPayload
             encodeDecodeAndCheck $ responseWith Stabilise stabResPayload
             encodeDecodeAndCheck $ responseWith Ping pingResPayload
-        it "messages are encoded and decoded to ASN.1 DER properly" $ do
+        it "messages are encoded and decoded to ASN.1 DER properly" $
             deserialiseMessage (head $ serialiseMessage 652  $ responseWith Ping pingResPayload) `shouldBe` Right (responseWith Ping pingResPayload)
+        it "messages too large for a single packet can (often) be split into multiple parts" $ do
+            let largeMessage = responseWith Join $ JoinResponsePayload {
+                joinSuccessors = fromInteger <$> [-20..150]
+              , joinPredecessors = fromInteger <$> [5..11]
+              , joinCache = [ RemoteCacheEntry (exampleNodeState {nid = node}) 290001 | node <- [50602,506011..60000]]
+                                                                       }
+            -- TODO: once splitting works more efficient, test for exact number or payload, see #18
+            length (serialiseMessage 600 largeMessage) > 1 `shouldBe` True
+            length (serialiseMessage 6000 largeMessage) `shouldBe` 1
 
 
 -- some example data