prevent Task.Cron and Task.Gate waiting to be set together (#28)

engine/create.go

@@ -111,7 +111,7 @@ func (e *Engine) verCre(tas *task.Task) (*ticker.Ticker, error) {
 			return nil, tracer.Maskf(taskCronError, "Task.Cron and Task.Root must not be configured together")
 		}
 		if tas.Gate != nil && tas.Root != nil {
-			return nil, tracer.Maskf(taskCronError, "Task.Gate and Task.Root must not be configured together")
+			return nil, tracer.Maskf(taskGateError, "Task.Gate and Task.Root must not be configured together")
 		}
 	}
 
@@ -151,7 +151,9 @@ func (e *Engine) verCre(tas *task.Task) (*ticker.Ticker, error) {
 			if tri && wai {
 				return nil, tracer.Maskf(labelValueError, "Task.Gate must not contain both of the reserved values [trigger waiting] together")
 			}
-
+			if wai && tas.Cron != nil {
+				return nil, tracer.Maskf(labelValueError, "Task.Gate must not contain the reserved value [waiting] if Task.Cron is configured")
+			}
 			if v != task.Trigger && v != task.Waiting {
 				return nil, tracer.Maskf(labelValueError, "Task.Gate must only contain one of the reserved values [trigger waiting]")
 			}

engine/create_test.go

@@ -54,7 +54,25 @@ func Test_Engine_Create_Gate_No_Error(t *testing.T) {
 				},
 			},
 		},
-		// Case 001 ensures that trigger tasks can define a multiple trigger labels.
+		// Case 001 ensures that task templates defining Task.Cron can schedule
+		// trigger tasks with Task.Gate definitions containing the reserved value
+		// "trigger".
+		{
+			tas: &task.Task{
+				Cron: &task.Cron{
+					task.Aevery: "hour",
+				},
+				Meta: &task.Meta{
+					"foo": "bar",
+				},
+				Gate: &task.Gate{
+					"foo": task.Trigger,
+					"bar": task.Trigger,
+					"baz": task.Trigger,
+				},
+			},
+		},
+		// Case 002 ensures that trigger tasks can define a multiple trigger labels.
 		{
 			tas: &task.Task{
 				Meta: &task.Meta{
@@ -67,7 +85,7 @@ func Test_Engine_Create_Gate_No_Error(t *testing.T) {
 				},
 			},
 		},
-		// Case 002 ensures that task templates can define a single waiting label.
+		// Case 003 ensures that task templates can define a single waiting label.
 		{
 			tas: &task.Task{
 				Meta: &task.Meta{
@@ -78,7 +96,7 @@ func Test_Engine_Create_Gate_No_Error(t *testing.T) {
 				},
 			},
 		},
-		// Case 003 ensures that task templates can define a multiple waiting
+		// Case 004 ensures that task templates can define a multiple waiting
 		// labels.
 		{
 			tas: &task.Task{
@@ -260,6 +278,21 @@ func Test_Engine_Create_Gate_Error(t *testing.T) {
 				},
 			},
 		},
+		// Case 012 ensures that the reserved value "waiting" in Task.Gate cannot be
+		// used together with task.Cron.
+		{
+			tas: &task.Task{
+				Cron: &task.Cron{
+					task.Aevery: "hour",
+				},
+				Meta: &task.Meta{
+					"foo": "bar",
+				},
+				Gate: &task.Gate{
+					"baz": task.Waiting,
+				},
+			},
+		},
 	}
 
 	for i, tc := range testCases {

engine/engine_lifecycle_redis_test.go

@@ -1064,8 +1064,8 @@ func Test_Engine_Lifecycle_Cron_Resolve(t *testing.T) {
 		}
 	}
 
-	// Verify the scheduled task that should contain Task.Gate, Task.Root and
-	// Task.Sync according to the task template emitting it.
+	// Verify the scheduled task that should contain Task.Gate, Task.Meta,
+	// Task.Root and Task.Sync according to the task template emitting it.
 	{
 		var tas *task.Task
 		{

engine/error.go

@@ -46,6 +46,14 @@ func IsTaskEmpty(err error) bool {
 	return errors.Is(err, taskEmptyError)
 }
 
+var taskGateError = &tracer.Error{
+	Kind: "taskGateError",
+}
+
+func IsTaskGate(err error) bool {
+	return errors.Is(err, taskGateError)
+}
+
 var taskMetaEmptyError = &tracer.Error{
 	Kind: "taskMetaEmptyError",
 }

engine/ticker.go

@@ -200,11 +200,11 @@ func (e *Engine) ticker() error {
 		// still exist, then we cannot schedule another one. Regardless, we have to
 		// update the task template's tick+1 below.
 		if !exi {
-			// Create a new scheduled task with the template's Task.Meta, Task.Root
-			// and Task.Sync reference. Note that scheduled tasks have a reserved
-			// label reference of the parents object ID in their root directory,
-			// pointing to the task template that defines their job description and
-			// scheduling information.
+			// Create a new scheduled task with the template's Task.Gate, Task.Meta,
+			// Task.Root and Task.Sync reference. Note that scheduled tasks have a
+			// reserved label reference of the parents object ID in their root
+			// directory, pointing to the task template that defines their job
+			// description and scheduling information.
 			var t *task.Task
 			{
 				t = &task.Task{