From 75a589d83340b7c5a904343e03681523acfd8557 Mon Sep 17 00:00:00 2001
From: Spencer Judge <spencer@temporal.io>
Date: Wed, 20 Jan 2021 16:31:46 -0800
Subject: [PATCH] Fix child workflow cancel invalid fsm transition (#344)

We just were missing an acceptable transition
---
 internal/internal_decision_state_machine.go |  7 +++-
 test/integration_test.go                    | 41 +++++++++++++++++++++
 test/workflow_test.go                       | 35 ++++++++++++++++++
 3 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/internal/internal_decision_state_machine.go b/internal/internal_decision_state_machine.go
index 830800568..2d35e5252 100644
--- a/internal/internal_decision_state_machine.go
+++ b/internal/internal_decision_state_machine.go
@@ -221,8 +221,10 @@ func (d commandState) String() string {
 		return "Completed"
 	case commandStateCanceledBeforeSent:
 		return "CanceledBeforeSent"
+	case commandStateCancellationCommandAccepted:
+		return "CancellationCommandAccepted"
 	default:
-		return "Unknown"
+		return fmt.Sprintf("Unknown: %d", int32(d))
 	}
 }
 
@@ -667,7 +669,8 @@ func (d *childWorkflowCommandStateMachine) handleCanceledEvent() {
 
 func (d *childWorkflowCommandStateMachine) handleCompletionEvent() {
 	switch d.state {
-	case commandStateStarted, commandStateCanceledAfterStarted, commandStateCompletedAfterCancellationCommandSent:
+	case commandStateStarted, commandStateCanceledAfterStarted,
+		commandStateCompletedAfterCancellationCommandSent, commandStateCancellationCommandAccepted:
 		d.moveState(commandStateCompleted, eventCompletion)
 	default:
 		d.commandStateMachineBase.handleCompletionEvent()
diff --git a/test/integration_test.go b/test/integration_test.go
index 5bb3d7db2..1e14211f3 100644
--- a/test/integration_test.go
+++ b/test/integration_test.go
@@ -600,6 +600,47 @@ func (ts *IntegrationTestSuite) TestCancelChildWorkflow() {
 	ts.EqualValues(expected, ts.activities.invoked())
 }
 
+func (ts *IntegrationTestSuite) TestCancelChildWorkflowUnusualTransitions() {
+	wfid := "test-cancel-child-workflow-unusual-transitions"
+	run, err := ts.client.ExecuteWorkflow(context.Background(),
+		ts.startWorkflowOptions(wfid),
+		ts.workflows.ChildWorkflowCancelUnusualTransitionsRepro)
+	ts.NoError(err)
+
+	// Give it a sec to populate the query
+	<-time.After(1 * time.Second)
+
+	v, err := ts.client.QueryWorkflow(context.Background(), run.GetID(), "", "child-workflow-id")
+	ts.NoError(err)
+
+	var childWorkflowID string
+	err = v.Get(&childWorkflowID)
+	ts.NoError(err)
+	ts.NotNil(childWorkflowID)
+	ts.NotEmpty(childWorkflowID)
+
+	err = ts.client.CancelWorkflow(context.Background(), childWorkflowID, "")
+	ts.NoError(err)
+
+	err = ts.client.CancelWorkflow(context.Background(), run.GetID(), "")
+	ts.NoError(err)
+
+	err = ts.client.SignalWorkflow(
+		context.Background(),
+		childWorkflowID,
+		"",
+		"unblock",
+		nil,
+	)
+	ts.NoError(err)
+
+	// Synchronously wait for the workflow completion. Behind the scenes the SDK performs a long poll operation.
+	// If you need to wait for the workflow completion from another process use
+	// Client.GetWorkflow API to get an instance of a WorkflowRun.
+	err = run.Get(context.Background(), nil)
+	ts.NoError(err)
+}
+
 func (ts *IntegrationTestSuite) TestCancelActivityImmediately() {
 	ts.T().Skip(`Currently fails with "PanicError": "unknown command internal.commandID{commandType:0, id:"5"}, possible causes are nondeterministic workflow definition code or incompatible change in the workflow definition`)
 	var expected []string
diff --git a/test/workflow_test.go b/test/workflow_test.go
index fa547ead4..88713e3d1 100644
--- a/test/workflow_test.go
+++ b/test/workflow_test.go
@@ -397,6 +397,39 @@ func (w *Workflows) ChildWorkflowSuccessWithParentClosePolicyAbandon(ctx workflo
 	err = ft.GetChildWorkflowExecution().Get(ctx, &childWE)
 	return childWE.ID, err
 }
+func (w *Workflows) childWorkflowWaitOnSignal(ctx workflow.Context) error {
+	workflow.GetSignalChannel(ctx, "unblock").Receive(ctx, nil)
+	return nil
+}
+
+func (w *Workflows) ChildWorkflowCancelUnusualTransitionsRepro(ctx workflow.Context) error {
+	var childWorkflowID string
+	err := workflow.SetQueryHandler(ctx, "child-workflow-id", func(input []byte) (string, error) {
+		return childWorkflowID, nil
+	})
+	if err != nil {
+		return err
+	}
+
+	cwo := workflow.ChildWorkflowOptions{WorkflowRunTimeout: time.Second * 2}
+	ctx = workflow.WithChildOptions(ctx, cwo)
+
+	childWorkflowFuture := workflow.ExecuteChildWorkflow(ctx, w.childWorkflowWaitOnSignal)
+
+	var childWorkflowExecution workflow.Execution
+	err = childWorkflowFuture.GetChildWorkflowExecution().Get(ctx, &childWorkflowExecution)
+	if err != nil {
+		return err
+	}
+	childWorkflowID = childWorkflowExecution.ID
+
+	var result string
+	err = childWorkflowFuture.Get(ctx, &result)
+	if err != nil {
+		return err
+	}
+	return nil
+}
 
 func (w *Workflows) ActivityCancelRepro(ctx workflow.Context) ([]string, error) {
 	ctx, cancelFunc := workflow.WithCancel(ctx)
@@ -1087,6 +1120,7 @@ func (w *Workflows) register(worker worker.Worker) {
 	worker.RegisterWorkflow(w.ChildWorkflowSuccess)
 	worker.RegisterWorkflow(w.ChildWorkflowSuccessWithParentClosePolicyTerminate)
 	worker.RegisterWorkflow(w.ChildWorkflowSuccessWithParentClosePolicyAbandon)
+	worker.RegisterWorkflow(w.ChildWorkflowCancelUnusualTransitionsRepro)
 	worker.RegisterWorkflow(w.ConsistentQueryWorkflow)
 	worker.RegisterWorkflow(w.ContextPropagator)
 	worker.RegisterWorkflow(w.ContinueAsNew)
@@ -1111,6 +1145,7 @@ func (w *Workflows) register(worker worker.Worker) {
 
 	worker.RegisterWorkflow(w.child)
 	worker.RegisterWorkflow(w.childForMemoAndSearchAttr)
+	worker.RegisterWorkflow(w.childWorkflowWaitOnSignal)
 	worker.RegisterWorkflow(w.sleep)
 	worker.RegisterWorkflow(w.timer)
 }