Add test to verify round-trip-ability

Author: bgamari

ghc-events.cabal

@@ -126,3 +126,11 @@ test-suite write-merge
   build-depends:    ghc-events, base, bytestring
   extensions:	      RecordWildCards, NamedFieldPuns, BangPatterns, PatternGuards
   buildable:        False
+
+test-suite roundtrip
+  type:             exitcode-stdio-1.0
+  main-is:          Roundtrip.hs
+  other-modules:    Utils
+  hs-source-dirs:   ., test
+  build-depends:    ghc-events, base
+  extensions:	      RecordWildCards, NamedFieldPuns, BangPatterns, PatternGuards

test/Roundtrip.hs

@@ -0,0 +1,22 @@
+import Control.Monad
+import System.Exit
+
+import GHC.RTS.Events
+import GHC.RTS.Events.Incremental
+import Utils (files, diffLines)
+
+-- | Check that an eventlog round-trips through encoding/decoding.
+checkRoundtrip :: FilePath -> IO Bool
+checkRoundtrip logFile = do
+  putStrLn logFile
+  Right eventlog <- readEventLogFromFile logFile
+  let Right (roundtripped, _) = readEventLog $ serialiseEventLog eventlog
+  let getEvents = sortEvents . events . dat
+  if show roundtripped == show eventlog
+    then return True
+    else putStrLn "bad" >> return False
+
+main :: IO ()
+main = do
+  successes <- mapM checkRoundtrip files
+  unless (and successes) exitFailure