1 files changed, 27 insertions, 0 deletions
diff --git a/libraries/compact/tests/compact_autoexpand.hs b/libraries/compact/tests/compact_autoexpand.hs
new file mode 100644
index 0000000000..5db0bbc55f
--- /dev/null
+++ b/libraries/compact/tests/compact_autoexpand.hs
@@ -0,0 +1,27 @@
+module Main where
+
+import Control.Exception
+import System.Mem
+
+import Data.Compact
+
+assertFail :: String -> IO ()
+assertFail msg = throwIO $ AssertionFailed msg
+
+assertEquals :: (Eq a, Show a) => a -> a -> IO ()
+assertEquals expected actual =
+  if expected == actual then return ()
+  else assertFail $ "expected " ++ (show expected)
+       ++ ", got " ++ (show actual)
+
+main = do
+  -- create a compact large 4096 bytes (minus the size of header)
+  -- add a value that is 1024 cons cells, pointing to 7 INTLIKE
+  -- each cons cell is 1 word header, 1 word data, 1 word next
+  -- so total 3072 words, 12288 bytes on x86, 24576 on x86_64
+  -- it should not fit in one block
+  let val = replicate 4096 7 :: [Int]
+  str <- newCompact 1 val
+  assertEquals val (getCompact str)
+  performMajorGC
+  assertEquals val (getCompact str)