Merge pull request #498 from input-output-hk/ensemble/implement-liven…

…ess-in-DL

Implement liveness property in dynamic logic

cabal.project

@@ -255,5 +255,7 @@ allow-newer:
 source-repository-package
   type: git
   location: https://github.com/input-output-hk/quickcheck-dynamic
-  tag: c272906361471d684440f76c297e29ab760f6a1e
-  --sha256: 1b9ppgavqad78a2z1zxv7v4jasjz6zz0mxkr0zx0bbcd0i00jajf
+  tag: 1.1.0
+  --sha256: 17cf58b36db5xpa0h4rbv62i7zdmknhmzz0g0znlb0mglfn7w2aj
+  subdir:
+    quickcheck-dynamic

hydra-node/test/Hydra/BehaviorSpec.hs

@@ -479,6 +479,20 @@ waitUntilMatch nodes predicate =
 
   veryLong = 31557600000 -- 1000 years
 
+-- | Wait for an output matching the predicate and extracting some value. This
+-- will loop forever until a match has been found.
+waitMatch ::
+  (MonadThrow m) =>
+  TestHydraNode tx m ->
+  (ServerOutput tx -> Maybe a) ->
+  m a
+waitMatch node predicate =
+  go
+ where
+  go = do
+    next <- waitForNext node
+    maybe go pure (predicate next)
+
 -- | A thin layer around 'HydraNode' to be able to 'waitFor'.
 data TestHydraNode tx m = TestHydraNode
   { send :: ClientInput tx -> m ()