Quickcheck-dynamic test fails.

[zmrocze]

Summary

Quickcheck-dynamic test fails. This happens sort of rarely.

Steps to reproduce the behavior

1. run on main or next-node

cabal run quickcheck-dynamic-test -- --quickcheck-replay=912838

Actual Result

dynamic logic
  registry model example
    prop_Registry: FAIL (0.06s)
      *** Failed! Assertion failed (after 5 tests):
      Actions 
       [Var 1 := Spawn,
        Var 2 := WhereIs "b",
        Var 3 := KillThread (Var 1),
        Var 4 := WhereIs "e",
        Var 5 := Register "e" (Var 1),
        Var 6 := Spawn,
        Var 7 := WhereIs "d"]
      
      Execution
      
      
      State: RegState {tids = [Var 1], regs = [], dead = []}
      
      
      State: RegState {tids = [Var 1], regs = [], dead = []}
      
      
      State: RegState {tids = [Var 1], regs = [], dead = [Var 1]}
      
      
      State: RegState {tids = [Var 1], regs = [], dead = [Var 1]}
      
      
      State: RegState {tids = [Var 1], regs = [], dead = [Var 1]}
      
      Use --quickcheck-replay=912838 to reproduce.

1 out of 1 tests failed (0.06s)

Expected Result

test passes

Describe the approach you would take to fix this

No response

System info

main branch on 61de89d
or
next-node branch on b8d3a89

[zmrocze]

--quickcheck-replay=957679 also fails

[UlfNorell]

As far as I can tell, the failure is caused by a thread still being alive 1ms after it was killed. It only happens for the very first test, so it might be caused by the run-time system not being warmed up properly. A work-around that seems to work is to add a test that waits 100ms before testing the actual property:

testProperty "Wait for run-time system to warm up??" $ withMaxSuccess 1 $ ioProperty $ do
  True <$ threadDelay 100000

IMO this is a bad test for the StateModel framework; there's no reason to involve IO and concurrency. It would be better to write a mock-up implementation of the registry example using a simple state monad and run the tests on that instead.

[ghost]

@UlfNorell Thanks!