add new watch event type

pkg/watch/watch.go

@@ -41,14 +41,18 @@ const (
 	Added    EventType = "ADDED"
 	Modified EventType = "MODIFIED"
 	Deleted  EventType = "DELETED"
+	Error    EventType = "ERROR"
 )
 
 // Event represents a single event to a watched resource.
 type Event struct {
 	Type EventType
 
-	// If Type == Deleted, then this is the state of the object
-	// immediately before deletion.
+	// Object is:
+	//  * If Type is Added or Modified: the new state of the object.
+	//  * If Type is Deleted: the state of the object immediately before deletion.
+	//  * If Type is Error: *api.Status is recommended; other types may make sense
+	//    depending on context.
 	Object runtime.Object
 }
 
@@ -94,6 +98,11 @@ func (f *FakeWatcher) Delete(lastValue runtime.Object) {
 	f.result <- Event{Deleted, lastValue}
 }
 
+// Error sends an Error event.
+func (f *FakeWatcher) Error(errValue runtime.Object) {
+	f.result <- Event{Error, errValue}
+}
+
 // Action sends an event of the requested type, for table-based testing.
 func (f *FakeWatcher) Action(action EventType, obj runtime.Object) {
 	f.result <- Event{action, obj}

pkg/watch/watch_test.go

@@ -35,6 +35,7 @@ func TestFake(t *testing.T) {
 		{Modified, testType("qux")},
 		{Modified, testType("bar")},
 		{Deleted, testType("bar")},
+		{Error, testType("error: blah")},
 	}
 
 	// Prove that f implements Interface by phrasing this as a function.
@@ -62,6 +63,7 @@ func TestFake(t *testing.T) {
 		f.Action(Modified, testType("qux"))
 		f.Modify(testType("bar"))
 		f.Delete(testType("bar"))
+		f.Error(testType("error: blah"))
 		f.Stop()
 	}