Added fix and tests for handling labels that have a prefix that can o…

…nly exist once per issue

Signed-off-by: Raghav Roy <raghavroy145@gmail.com>

prow/plugins/config.go

@@ -391,6 +391,9 @@ type Label struct {
 	// defines to which repos this applies and can be `*` for global, an org
 	// or a repo in org/repo notation.
 	RestrictedLabels map[string][]RestrictedLabel `json:"restricted_labels,omitempty"`
+	// UniquePrefixList is the list of label prefixes that can only exist
+	// once per issue,
+	UniquePrefixes []string `json:"unique_prefixes,omitempty"`
 }
 
 func (l Label) RestrictedLabelsFor(org, repo string) map[string]RestrictedLabel {
@@ -2032,7 +2035,7 @@ func getLabelConfigFromRestrictedLabelsSlice(s []RestrictedLabel, label string)
 func (c *Configuration) HasConfigFor() (global bool, orgs sets.String, repos sets.String) {
 	equals := reflect.DeepEqual(c,
 		&Configuration{Approve: c.Approve, Bugzilla: c.Bugzilla, ExternalPlugins: c.ExternalPlugins,
-			Label: Label{RestrictedLabels: c.Label.RestrictedLabels}, Lgtm: c.Lgtm, Plugins: c.Plugins,
+			Label: Label{RestrictedLabels: c.Label.RestrictedLabels, UniquePrefixes: c.Label.UniquePrefixes}, Lgtm: c.Lgtm, Plugins: c.Plugins,
 			Triggers: c.Triggers, Welcome: c.Welcome})
 
 	if !equals || c.Bugzilla.Default != nil {

prow/plugins/label/label.go

@@ -1,12 +1,9 @@
 /*
 Copyright 2016 The Kubernetes Authors.
-
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
-
     http://www.apache.org/licenses/LICENSE-2.0
-
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -49,6 +46,20 @@ func init() {
 	plugins.RegisterPullRequestHandler(PluginName, handlePullRequest, helpProvider)
 }
 
+// returns a list of labels for every label prefix that can only exist once per issue
+func getExistingUniquePrefixlabels(config plugins.Label, labels []github.Label) map[string][]string {
+	labelsMap := make(map[string][]string)
+	prefixList := config.UniquePrefixes
+	for _, prefix := range prefixList {
+		for _, label := range labels {
+			if matched, _ := regexp.MatchString(prefix, label.Name); matched {
+				labelsMap[prefix] = append(labelsMap[prefix], label.Name)
+			}
+		}
+	}
+	return labelsMap
+}
+
 func configString(labels []string) string {
 	var formattedLabels []string
 	for _, label := range labels {
@@ -168,7 +179,15 @@ func handleComment(gc githubClient, log *logrus.Entry, config plugins.Label, e *
 	if err != nil {
 		return err
 	}
-
+	var labelsMap = make(map[string][]string)
+	for _, label := range labels {
+		labelSplit := strings.Split(label.Name, "/")
+		// The second check (labelSplit[0] == "priority") can be removed or extended in the future to generalise
+		// the functionality of removing labels of the same class
+		if len(labelSplit) == 2 && labelSplit[0] == "priority" {
+			labelsMap[labelSplit[0]] = append(labelsMap[labelSplit[0]], labelSplit[1])
+		}
+	}
 	RepoLabelsExisting := sets.String{}
 	for _, l := range repoLabels {
 		RepoLabelsExisting.Insert(strings.ToLower(l.Name))
@@ -180,6 +199,7 @@ func handleComment(gc githubClient, log *logrus.Entry, config plugins.Label, e *
 		labelsToAdd             []string
 		labelsToRemove          []string
 		nonMemberTriageAccepted bool
+		labelPrefix             string
 	)
 
 	additionalLabelSet := sets.String{}
@@ -228,12 +248,33 @@ func handleComment(gc githubClient, log *logrus.Entry, config plugins.Label, e *
 			gc.CreateComment(org, repo, e.Number, plugins.FormatResponseRaw(bodyWithoutComments, e.HTMLURL, e.User.Login, canNotSetLabelReason))
 			continue
 		}
-
-		if err := gc.AddLabel(org, repo, e.Number, labelToAdd); err != nil {
-			log.WithError(err).WithField("label", labelToAdd).Error("GitHub failed to add the label")
+		uniqueLabelsMap := getExistingUniquePrefixlabels(config, labels)
+		var labelsWithPrefixExist = false
+		for prefix := range uniqueLabelsMap {
+			if matched, _ := regexp.MatchString(prefix, labelToAdd); matched {
+				labelPrefix = prefix
+				labelsWithPrefixExist = true
+			}
+		}
+		if !github.HasLabel(labelToAdd, labels) {
+			if labelsWithPrefixExist {
+				for _, label := range uniqueLabelsMap[labelPrefix] {
+					if label != labelToAdd && github.HasLabel(label, labels) {
+						if err := gc.RemoveLabel(org, repo, e.Number, label); err != nil {
+							log.WithError(err).Errorf("GitHub failed to remove the following label: %s", label)
+						}
+					}
+				}
+				if err := gc.AddLabel(org, repo, e.Number, labelToAdd); err != nil {
+					log.WithError(err).WithField("label", labelToAdd).Error("GitHub failed to add the label")
+				}
+			} else {
+				if err := gc.AddLabel(org, repo, e.Number, labelToAdd); err != nil {
+					log.WithError(err).WithField("label", labelToAdd).Error("GitHub failed to add the label")
+				}
+			}
 		}
 	}
-
 	// Remove labels
 	for _, labelToRemove := range labelsToRemove {
 		if !github.HasLabel(labelToRemove, labels) {

prow/plugins/label/label_test.go

@@ -64,6 +64,7 @@ func TestHandleComment(t *testing.T) {
 		expectedCommentText   string
 		action                github.GenericCommentEventAction
 		teams                 map[string]map[string]fakegithub.TeamWithMembers
+		uniquePrefixList      []string
 	}
 	testcases := []testCase{
 		{
@@ -475,6 +476,17 @@ func TestHandleComment(t *testing.T) {
 			commenter:             orgMember,
 			action:                github.GenericCommentActionCreated,
 		},
+		{
+			name:                  "Add label that has a prefix that can only exist once per issue",
+			body:                  "/priority urgent",
+			repoLabels:            []string{"area/go", "priority/urgent", "priority/critical", "priority/l"},
+			issueLabels:           []string{"area/go", "priority/critical", "priority/l"},
+			expectedNewLabels:     formatWithPRInfo("priority/urgent"),
+			expectedRemovedLabels: formatWithPRInfo("priority/critical", "priority/l"),
+			commenter:             orgMember,
+			action:                github.GenericCommentActionCreated,
+			uniquePrefixList:      []string{"^priority/"},
+		},
 		{
 			name:                  "Do nothing with empty /label command",
 			body:                  "/label",
@@ -762,7 +774,7 @@ func TestHandleComment(t *testing.T) {
 				Repo:   github.Repo{Owner: github.User{Login: "org"}, Name: "repo"},
 				User:   github.User{Login: tc.commenter},
 			}
-			err := handleComment(fakeClient, logrus.WithField("plugin", PluginName), plugins.Label{AdditionalLabels: tc.extraLabels, RestrictedLabels: tc.restrictedLabels}, e)
+			err := handleComment(fakeClient, logrus.WithField("plugin", PluginName), plugins.Label{AdditionalLabels: tc.extraLabels, RestrictedLabels: tc.restrictedLabels, UniquePrefixes: tc.uniquePrefixList}, e)
 			if err != nil {
 				t.Fatalf("didn't expect error from handle comment test: %v", err)
 			}

prow/plugins/plugin-config-documented.yaml

@@ -472,6 +472,11 @@ label:
     # or a repo in org/repo notation.
     restricted_labels:
         "": null
+
+    # UniquePrefixList is the list of label prefixes that can only exist
+    # once per issue.
+    unique_prefixes:
+      - ""
 lgtm:
   - # Repos is either of the form org/repos or just org.
     repos: