create a test for parts of #48

test/FediChordSpec.hs

@@ -148,6 +148,27 @@ spec = do
         it "does not fail on nodes without neighbours (initial state)" $ do
             (FORWARD nodeset) <- queryLocalCache <$> exampleLocalNode <*> cacheWith4Entries <*> pure 3 <*> pure (toNodeID 11)
             Set.map (nid . remoteNode ) nodeset `shouldBe` Set.fromList [nid4, nid2, nid3]
+    describe "successors and predecessors do not disturb the ring characteristics of EpiChord operations (see #48)" $ do
+        let
+            emptyCache = initCache
+            -- implicitly relies on kNieghbours to be <= 3
+            thisNid = toNodeID 1000
+            thisNode = setNid thisNid <$> exampleLocalNode
+            nid2 = toNodeID 1003
+            node2 = exampleNodeState { nid = nid2}
+            nid3 = toNodeID 1010
+            node3 = exampleNodeState { nid = nid3}
+            nid4 = toNodeID 1020
+            node4 = exampleNodeState { nid = nid4}
+            nid5 = toNodeID 1025
+            node5 = exampleNodeState { nid = nid5}
+            allRemoteNodes = [node2, node3, node4, node5]
+        it "lookups also work for slices larger than 1/2 key space" $ do
+            node <- setSuccessors allRemoteNodes . setPredecessors allRemoteNodes <$> thisNode
+            -- do lookup on empty cache but with successors for a key > 1/2 key space
+            -- succeeding the node
+            queryLocalCache node emptyCache 1 (nid5 + 10) `shouldBe` FOUND (toRemoteNodeState node)
+
 
     describe "Messages can be encoded to and decoded from ASN.1" $ do
         -- define test messages