cleanup

Signed-off-by: Tim Vaillancourt <[email protected]>

go/vt/discovery/topology_watcher.go

@@ -386,18 +386,24 @@ func (fbk *FilterByKeyspace) IsIncluded(tablet *topodata.Tablet) bool {
 	return exist
 }
 
-// TODO:
+// FilterByTabletTags is a filter that filters tablets by tablet tag key/values.
 type FilterByTabletTags struct {
 	tags map[string]string
 }
 
+// NewFilterByTabletTags creates a new FilterByTabletTags. All tablets that match
+// all tablet tags will be forwarded to the TopologyWatcher's consumer.
 func NewFilterByTabletTags(tabletTags map[string]string) *FilterByTabletTags {
-	return &FilterByTabletTags{tags: tabletTags}
+	return &FilterByTabletTags{
+		tags: tabletTags,
+	}
 }
 
 // IsIncluded returns true if the tablet's tags match what we expect.
 func (fbtg *FilterByTabletTags) IsIncluded(tablet *topodata.Tablet) bool {
-	if tablet.Tags == nil {
+	if fbtg.tags == nil {
+		return true
+	} else if tablet.Tags == nil {
 		return false
 	}
 	for key, val := range fbtg.tags {

go/vt/discovery/topology_watcher_test.go

@@ -579,11 +579,16 @@ func TestFilterByKeyspaceSkipsIgnoredTablets(t *testing.T) {
 }
 
 func TestNewFilterByTabletTags(t *testing.T) {
+	// no required tags == true
+	filter := NewFilterByTabletTags(nil)
+	assert.True(t, filter.IsIncluded(&topodatapb.Tablet{}))
+
 	tags := map[string]string{
 		"instance_type": "i3.xlarge",
 		"some_key":      "some_value",
 	}
-	filter := NewFilterByTabletTags(tags)
+	filter = NewFilterByTabletTags(tags)
+
 	assert.False(t, filter.IsIncluded(&topodatapb.Tablet{
 		Tags: nil,
 	}))