reproduce 'signalWithStart' failure

'signalWithStart' fails when the first thing executed is an Activity
that is scheduled, takes some amount of time to finish executing, and
is awaited _before_ the signal handler is installed.

Author: jkachmar

sdk/test/IntegrationSpec.hs

@@ -1482,6 +1482,31 @@ needsClient = do
                 2
             lift $ C.waitWorkflowResult wfH `shouldReturn` 25
 
+      it "works with workflow that starts an activity before installing the signal handler" $ \TestEnv {..} -> do
+        let conf = provideCallStack $ configure () (discoverDefinitions @() $$(discoverInstances) $$(discoverInstances)) baseConf
+        withWorker conf $ do
+          let opts =
+                (C.startWorkflowOptions taskQueue)
+                  { C.workflowIdReusePolicy = Just W.WorkflowIdReusePolicyAllowDuplicate
+                  , C.timeouts =
+                      C.TimeoutOptions
+                        { C.runTimeout = Just $ seconds 4
+                        , C.executionTimeout = Nothing
+                        , C.taskTimeout = Nothing
+                        }
+                  }
+          useClient $ do
+            liftIO $ putStrLn "signalWithStart call"
+            wfH <-
+              C.signalWithStart
+                SignalWithActivityWorkflow
+                "signalWithStartWithActivity"
+                opts
+                signalWithArgs
+                0
+                
+            lift $ C.waitWorkflowResult wfH `shouldReturn` 0
+
   --     specify "works as intended and returns correct runId" pending
   describe "RetryPolicy" $ do
     specify "is used for retryable failures" $ \TestEnv {..} -> do

sdk/test/IntegrationSpec/Signals.hs

@@ -9,10 +9,11 @@
 
 module IntegrationSpec.Signals where
 
-import Control.Exception
-import Control.Monad
-import Control.Monad.Logger
+import Control.Concurrent (threadDelay)
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Logger (logDebug)
 import RequireCallStack (provideCallStack)
+import Temporal.Activity (Activity)
 import Temporal.Duration
 import Temporal.Payload
 import Temporal.TH
@@ -53,3 +54,23 @@ signalWithArgsWorkflow init = provideCallStack do
 
 
 registerWorkflow 'signalWithArgsWorkflow
+
+
+signalWithActivityA :: Activity () ()
+signalWithActivityA =  liftIO $ threadDelay 1_000_000
+
+registerActivity 'signalWithActivityA
+
+signalWithActivityWorkflow :: Workflow Int
+signalWithActivityWorkflow = provideCallStack do
+  executeActivity SignalWithActivityA (defaultStartActivityOptions $ StartToClose $ seconds 2)
+
+  var <- newStateVar []
+  setSignalHandler signalWithArgs $ \i -> do
+    $(logDebug) "updating value and unblocking workflow"
+    readStateVar var >>= \s -> writeStateVar var (i : s)
+
+  waitCondition  (not . null) <$> readStateVar var
+  head <$> readStateVar var
+
+registerWorkflow 'signalWithActivityWorkflow