Fix canceling external workflows that are children in testsuite

internal/internal_workflow_testsuite.go

@@ -2281,9 +2281,16 @@ func (env *testWorkflowEnvironmentImpl) RequestCancelChildWorkflow(_, workflowID
 
 func (env *testWorkflowEnvironmentImpl) RequestCancelExternalWorkflow(namespace, workflowID, runID string, callback ResultHandler) {
 	if env.workflowInfo.WorkflowExecution.ID == workflowID {
-		// cancel current workflow
-		env.workflowCancelHandler()
-		// check if current workflow is a child workflow
+		// The way testWorkflowEnvironment is setup today, we close the child workflow dispatcher before calling
+		// the workflowCancelHandler. A larger refactor would be needed to handle this similar to non-test code.
+		// Maybe worth doing when https://github.com/temporalio/go-sdk/issues/50 is tackled.
+		if sd, ok := env.workflowDef.(*syncWorkflowDefinition); ok && env.isChildWorkflow() {
+			sd.dispatcher.NewCoroutine(sd.rootCtx, "cancel-self", true, func(ctx Context) {
+				env.workflowCancelHandler()
+			})
+		} else {
+			env.workflowCancelHandler()
+		}
 		if env.isChildWorkflow() && env.onChildWorkflowCanceledListener != nil {
 			env.postCallback(func() {
 				env.onChildWorkflowCanceledListener(env.workflowInfo)

internal/workflow_testsuite_test.go

@@ -1232,3 +1232,37 @@ func TestDynamicWorkflows(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, "dynamic-activity - grape - cherry", result)
 }
+
+func SleepHour(ctx Context) error {
+	return Sleep(ctx, time.Hour)
+}
+
+func SleepThenCancel(ctx Context) error {
+	cwf := ExecuteChildWorkflow(
+		ctx,
+		SleepHour,
+	)
+	var res WorkflowExecution
+	if err := cwf.GetChildWorkflowExecution().Get(ctx, &res); err != nil {
+		return err
+	}
+
+	// Canceling an external workflow that causes a timer to cancel used to fail due to
+	// "illegal access from outside of workflow context"
+	err := RequestCancelExternalWorkflow(ctx, res.ID, res.RunID).Get(ctx, nil)
+	if err != nil {
+		return err
+	}
+
+	// Give the workflow time to finish canceling the child workflow
+	return Sleep(ctx, 1*time.Second)
+}
+
+func TestRequestCancelExternalWorkflowInSelector(t *testing.T) {
+	testSuite := &WorkflowTestSuite{}
+	env := testSuite.NewTestWorkflowEnvironment()
+	env.RegisterWorkflow(SleepHour)
+	env.ExecuteWorkflow(SleepThenCancel)
+	require.NoError(t, env.GetWorkflowError())
+	env.IsWorkflowCompleted()
+}