add ability to mock start child workflow failed case (cadence-workflo…

…w#444)

internal/internal_event_handlers.go

@@ -962,7 +962,7 @@ func (weh *workflowExecutionEventHandlerImpl) handleStartChildWorkflowExecutionF
 		return nil
 	}
 
-	err := fmt.Errorf("ChildWorkflowFailed: %v", attributes.GetCause())
+	err := fmt.Errorf("start child workflow failed: %v", attributes.GetCause())
 	childWorkflow.startedCallback(WorkflowExecution{}, err)
 	childWorkflow.handle(nil, err)
 

internal/internal_workflow_testsuite.go

@@ -354,13 +354,6 @@ func (env *testWorkflowEnvironmentImpl) executeWorkflowInternal(workflowType str
 	// In case of child workflow, this executeWorkflowInternal() is run in separate goroutinue, so use postCallback
 	// to make sure workflowDef.Execute() is run in main loop.
 	env.postCallback(func() {
-		if env.isChildWorkflow() {
-			// notify parent that child workflow is started
-			env.parentEnv.postCallback(func() {
-				env.startedHandler(env.workflowInfo.WorkflowExecution, nil)
-			}, true)
-		}
-
 		env.workflowDef.Execute(env, input)
 	}, false)
 	env.startMainLoop()
@@ -968,8 +961,25 @@ func (w *workflowExecutorWrapper) Execute(ctx Context, input []byte) (result []b
 	// ExecuteUntilAllBlocked() returns).
 	env.runningCount--
 
+	childWE := env.workflowInfo.WorkflowExecution
+	var startedErr error
 	if mockRet != nil {
-		return m.executeMock(ctx, input, mockRet)
+		// workflow was mocked.
+		result, err = m.executeMock(ctx, input, mockRet)
+		if env.isChildWorkflow() && err == ErrMockStartChildWorkflowFailed {
+			childWE, startedErr = WorkflowExecution{}, err
+		}
+	}
+
+	if env.isChildWorkflow() {
+		// notify parent that child workflow is started
+		env.parentEnv.postCallback(func() {
+			env.startedHandler(childWE, startedErr)
+		}, true)
+	}
+
+	if mockRet != nil {
+		return result, err
 	}
 
 	// no mock, so call the actual workflow

internal/internal_workflow_testsuite_test.go

@@ -565,6 +565,28 @@ func (s *WorkflowTestSuiteUnitTest) Test_ChildWorkflow_Mock() {
 	s.Equal("mock_msg mock_msg mock_heartbeat", actualResult)
 }
 
+func (s *WorkflowTestSuiteUnitTest) Test_ChildWorkflow_StartFailed() {
+	workflowFn := func(ctx Context) (string, error) {
+		cwo := ChildWorkflowOptions{ExecutionStartToCloseTimeout: time.Minute}
+		ctx = WithChildWorkflowOptions(ctx, cwo)
+		err := ExecuteChildWorkflow(ctx, testWorkflowHello).GetChildWorkflowExecution().Get(ctx, nil)
+		if err != nil {
+			return "", errors.New("fail to start child")
+		}
+
+		return "should-not-go-here", nil
+	}
+
+	RegisterWorkflow(workflowFn)
+	env := s.NewTestWorkflowEnvironment()
+	env.OnWorkflow(testWorkflowHello, mock.Anything).Return("", ErrMockStartChildWorkflowFailed)
+	env.ExecuteWorkflow(workflowFn)
+
+	s.True(env.IsWorkflowCompleted())
+	s.Error(env.GetWorkflowError())
+	s.Equal("fail to start child", env.GetWorkflowError().Error())
+}
+
 func (s *WorkflowTestSuiteUnitTest) Test_ChildWorkflow_Listener() {
 	workflowFn := func(ctx Context) (string, error) {
 		ctx = WithActivityOptions(ctx, s.activityOptions)

internal/workflow_testsuite.go

@@ -22,13 +22,14 @@ package internal
 
 import (
 	"context"
+	"fmt"
 	"reflect"
 	"time"
 
-	"go.uber.org/cadence/encoded"
-
 	"github.com/stretchr/testify/mock"
 	"github.com/uber-go/tally"
+	"go.uber.org/cadence/.gen/go/shared"
+	"go.uber.org/cadence/encoded"
 	"go.uber.org/zap"
 )
 
@@ -168,6 +169,10 @@ func (t *TestWorkflowEnvironment) OnActivity(activity interface{}, args ...inter
 	return t.wrapCall(call)
 }
 
+// ErrMockStartChildWorkflowFailed is special error used to indicate the mocked child workflow should fail to start.
+// This error is also exposed as public as testsuite.ErrMockStartChildWorkflowFailed
+var ErrMockStartChildWorkflowFailed = fmt.Errorf("start child workflow failed: %v", shared.ChildWorkflowExecutionFailedCauseWorkflowAlreadyRunning)
+
 // OnWorkflow setup a mock call for workflow. Parameter workflow must be workflow function (func) or workflow name (string).
 // You must call Return() with appropriate parameters on the returned *MockCallWrapper instance. The supplied parameters to
 // the Return() call should either be a function that has exact same signature as the mocked workflow, or it should be
@@ -181,6 +186,8 @@ func (t *TestWorkflowEnvironment) OnActivity(activity interface{}, args ...inter
 //   })
 // OR return mock values with same types as workflow function's return types:
 //   t.OnWorkflow(MyChildWorkflow, mock.Anything, mock.Anything).Return("mock_result", nil)
+// You could also setup mock to simulate start child workflow failure case by returning ErrMockStartChildWorkflowFailed
+// as error.
 func (t *TestWorkflowEnvironment) OnWorkflow(workflow interface{}, args ...interface{}) *MockCallWrapper {
 	fType := reflect.TypeOf(workflow)
 	var call *mock.Call

testsuite/testsuite.go

@@ -38,3 +38,6 @@ type (
 	// MockCallWrapper is a wrapper to mock.Call. It offers the ability to wait on workflow's clock instead of wall clock.
 	MockCallWrapper = internal.MockCallWrapper
 )
+
+// ErrMockStartChildWorkflowFailed is special error used to indicate the mocked child workflow should fail to start.
+var ErrMockStartChildWorkflowFailed = internal.ErrMockStartChildWorkflowFailed