Filtering fix for consistency in handling empty string as value (#5273)

* filter-fix for empty string filters, dataschema added

* merged 2 similar if cases

* test added to check for consistency in filtering optional attributes and extensions

* comment added for this change

* gofmt done

pkg/eventfilter/attributes/filter.go

@@ -45,6 +45,7 @@ func (attrs attributesFilter) Filter(ctx context.Context, event cloudevents.Even
 		"subject":         event.Subject(),
 		"id":              event.ID(),
 		"time":            event.Time().String(),
+		"dataschema":      event.DataSchema(),
 		"schemaurl":       event.DataSchema(),
 		"datacontenttype": event.DataContentType(),
 		"datamediatype":   event.DataMediaType(),
@@ -59,8 +60,10 @@ func (attrs attributesFilter) Filter(ctx context.Context, event cloudevents.Even
 	for k, v := range attrs {
 		var value interface{}
 		value, ok := ce[k]
-		// If the attribute does not exist in the event, return false.
-		if !ok {
+		// If the attribute does not exist in the event (extension context attributes) or if the event attribute
+		// has an empty string value (optional attributes) - which means it was never set in the incoming event,
+		// return false.
+		if !ok || (v == eventingv1.TriggerAnyFilter && value == "") {
 			logging.FromContext(ctx).Debug("Attribute not found", zap.String("attribute", k))
 			return eventfilter.FailFilter
 		}

pkg/eventfilter/attributes/filter_test.go

@@ -31,6 +31,7 @@ const (
 	eventSource    = `/mycontext`
 	extensionName  = `myextension`
 	extensionValue = `my-extension-value`
+	subjectValue   = `mysubject`
 )
 
 func TestAttributesFilter_Filter(t *testing.T) {
@@ -72,6 +73,29 @@ func TestAttributesFilter_Filter(t *testing.T) {
 			event:  makeEventWithExtension(extensionName, extensionValue),
 			want:   eventfilter.PassFilter,
 		},
+		"Any Extension with attribs - without Extension in Event": {
+			filter: attributesWithExtension(eventType, eventSource, ""),
+			want:   eventfilter.FailFilter,
+		},
+		"Any Extension with attribs - with Extension in Event": {
+			filter: attributesWithExtension(eventType, eventSource, ""),
+			event:  makeEventWithExtension(extensionName, extensionValue),
+			want:   eventfilter.PassFilter,
+		},
+		"Subject with attribs": {
+			filter: attributesWithSubject(eventType, eventSource, subjectValue),
+			event:  makeEventWithSubject(subjectValue),
+			want:   eventfilter.PassFilter,
+		},
+		"Any Subject with attribs - without Subject in Event": {
+			filter: attributesWithSubject(eventType, eventSource, ""),
+			want:   eventfilter.FailFilter,
+		},
+		"Any Subject with attribs - with Subject in Event": {
+			filter: attributesWithSubject(eventType, eventSource, ""),
+			event:  makeEventWithSubject(subjectValue),
+			want:   eventfilter.PassFilter,
+		},
 		"Any with attribs - Arrival extension": {
 			filter: attributes("", ""),
 			event:  makeEventWithExtension(broker.EventArrivalTime, "2019-08-26T23:38:17.834384404Z"),
@@ -111,6 +135,12 @@ func makeEventWithExtension(extName, extValue string) *cloudevents.Event {
 	return e
 }
 
+func makeEventWithSubject(sub string) *cloudevents.Event {
+	e := makeEvent()
+	e.SetSubject(sub)
+	return e
+}
+
 func attributes(t, s string) map[string]string {
 	return map[string]string{
 		"type":   t,
@@ -125,3 +155,11 @@ func attributesWithExtension(t, s, e string) map[string]string {
 		extensionName: e,
 	}
 }
+
+func attributesWithSubject(t, s, sub string) map[string]string {
+	return map[string]string{
+		"type":    t,
+		"source":  s,
+		"subject": sub,
+	}
+}