[Fix] Trigger 'unlabeled' event when label is Deleted from PR (#34316)

This pull request updates the handling of issue label events in
workflows to distinguish between label additions and deletions,
introduces corresponding test cases, and extends the `IssuePayload`
structure to support this functionality.

### Enhancements to issue label event handling:
* Updated `matchIssuesEvent` in `modules/actions/workflows.go` to
differentiate between "labeled" and "unlabeled" events based on whether
labels were added or removed.
* Added a new field, `RemovedLabels`, to the `IssuePayload` struct in
`modules/structs/hook.go` to track labels that were removed during an
issue event.

### Testing improvements:
* Added `TestMatchIssuesEvent` in `modules/actions/workflows_test.go` to
cover scenarios such as label addition, label deletion, and label
clearing, ensuring the correct event type is triggered.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/actions/workflows.go

@@ -377,20 +377,28 @@ func matchIssuesEvent(issuePayload *api.IssuePayload, evt *jobparser.Event) bool
 			// Actions with the same name:
 			// opened, edited, closed, reopened, assigned, unassigned, milestoned, demilestoned
 			// Actions need to be converted:
-			// label_updated -> labeled
+			// label_updated -> labeled (when adding) or unlabeled (when removing)
 			// label_cleared -> unlabeled
 			// Unsupported activity types:
 			// deleted, transferred, pinned, unpinned, locked, unlocked
 
-			action := issuePayload.Action
-			switch action {
+			actions := []string{}
+			switch issuePayload.Action {
 			case api.HookIssueLabelUpdated:
-				action = "labeled"
-			case api.HookIssueLabelCleared:
-				action = "unlabeled"
+				if len(issuePayload.Changes.AddedLabels) > 0 {
+					actions = append(actions, "labeled")
 				}
+				if len(issuePayload.Changes.RemovedLabels) > 0 {
+					actions = append(actions, "unlabeled")
+				}
+			case api.HookIssueLabelCleared:
+				actions = append(actions, "unlabeled")
+			default:
+				actions = append(actions, string(issuePayload.Action))
+			}
+
 			for _, val := range vals {
-				if glob.MustCompile(val, '/').Match(string(action)) {
+				if slices.ContainsFunc(actions, glob.MustCompile(val, '/').Match) {
 					matchTimes++
 					break
 				}

modules/actions/workflows_test.go

@@ -154,3 +154,184 @@ func TestDetectMatched(t *testing.T) {
 		})
 	}
 }
+
+func TestMatchIssuesEvent(t *testing.T) {
+	testCases := []struct {
+		desc      string
+		payload   *api.IssuePayload
+		yamlOn    string
+		expected  bool
+		eventType string
+	}{
+		{
+			desc: "Label deletion should trigger unlabeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{},
+				},
+				Changes: &api.ChangesPayload{
+					RemovedLabels: []*api.Label{
+						{ID: 123, Name: "deleted-label"},
+					},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [unlabeled]",
+			expected:  true,
+			eventType: "unlabeled",
+		},
+		{
+			desc: "Label deletion with existing labels should trigger unlabeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{
+						{ID: 456, Name: "existing-label"},
+					},
+				},
+				Changes: &api.ChangesPayload{
+					AddedLabels: nil,
+					RemovedLabels: []*api.Label{
+						{ID: 123, Name: "deleted-label"},
+					},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [unlabeled]",
+			expected:  true,
+			eventType: "unlabeled",
+		},
+		{
+			desc: "Label addition should trigger labeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{
+						{ID: 123, Name: "new-label"},
+					},
+				},
+				Changes: &api.ChangesPayload{
+					AddedLabels: []*api.Label{
+						{ID: 123, Name: "new-label"},
+					},
+					RemovedLabels: []*api.Label{}, // Empty array, no labels removed
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [labeled]",
+			expected:  true,
+			eventType: "labeled",
+		},
+		{
+			desc: "Label clear should trigger unlabeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelCleared,
+				Issue: &api.Issue{
+					Labels: []*api.Label{},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [unlabeled]",
+			expected:  true,
+			eventType: "unlabeled",
+		},
+		{
+			desc: "Both adding and removing labels should trigger labeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+				},
+				Changes: &api.ChangesPayload{
+					AddedLabels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+					RemovedLabels: []*api.Label{
+						{ID: 123, Name: "deleted-label"},
+					},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [labeled]",
+			expected:  true,
+			eventType: "labeled",
+		},
+		{
+			desc: "Both adding and removing labels should trigger unlabeled event",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+				},
+				Changes: &api.ChangesPayload{
+					AddedLabels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+					RemovedLabels: []*api.Label{
+						{ID: 123, Name: "deleted-label"},
+					},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [unlabeled]",
+			expected:  true,
+			eventType: "unlabeled",
+		},
+		{
+			desc: "Both adding and removing labels should trigger both events",
+			payload: &api.IssuePayload{
+				Action: api.HookIssueLabelUpdated,
+				Issue: &api.Issue{
+					Labels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+				},
+				Changes: &api.ChangesPayload{
+					AddedLabels: []*api.Label{
+						{ID: 789, Name: "new-label"},
+					},
+					RemovedLabels: []*api.Label{
+						{ID: 123, Name: "deleted-label"},
+					},
+				},
+			},
+			yamlOn:    "on:\n  issues:\n    types: [labeled, unlabeled]",
+			expected:  true,
+			eventType: "multiple",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			evts, err := GetEventsFromContent([]byte(tc.yamlOn))
+			assert.NoError(t, err)
+			assert.Len(t, evts, 1)
+
+			// Test if the event matches as expected
+			assert.Equal(t, tc.expected, matchIssuesEvent(tc.payload, evts[0]))
+
+			// For extra validation, check that action mapping works correctly
+			if tc.eventType == "multiple" {
+				// Skip direct action mapping validation for multiple events case
+				// as one action can map to multiple event types
+				return
+			}
+
+			// Determine expected action for single event case
+			var expectedAction string
+			switch tc.payload.Action {
+			case api.HookIssueLabelUpdated:
+				if tc.eventType == "labeled" {
+					expectedAction = "labeled"
+				} else if tc.eventType == "unlabeled" {
+					expectedAction = "unlabeled"
+				}
+			case api.HookIssueLabelCleared:
+				expectedAction = "unlabeled"
+			default:
+				expectedAction = string(tc.payload.Action)
+			}
+
+			assert.Equal(t, expectedAction, tc.eventType, "Event type should match expected")
+		})
+	}
+}

modules/structs/hook.go

@@ -418,6 +418,10 @@ type ChangesPayload struct {
 	Body *ChangesFromPayload `json:"body,omitempty"`
 	// Changes made to the reference
 	Ref *ChangesFromPayload `json:"ref,omitempty"`
+	// Changes made to the labels added
+	AddedLabels []*Label `json:"added_labels"`
+	// Changes made to the labels removed
+	RemovedLabels []*Label `json:"removed_labels"`
 }
 
 // PullRequestPayload represents a payload information of pull request event.

services/actions/notifier.go

@@ -169,7 +169,7 @@ func (n *actionsNotifier) IssueChangeAssignee(ctx context.Context, doer *user_mo
 		hookEvent = webhook_module.HookEventPullRequestAssign
 	}
 
-	notifyIssueChange(ctx, doer, issue, hookEvent, action)
+	notifyIssueChange(ctx, doer, issue, hookEvent, action, nil, nil)
 }
 
 // IssueChangeMilestone notifies assignee to notifiers
@@ -188,11 +188,11 @@ func (n *actionsNotifier) IssueChangeMilestone(ctx context.Context, doer *user_m
 		hookEvent = webhook_module.HookEventPullRequestMilestone
 	}
 
-	notifyIssueChange(ctx, doer, issue, hookEvent, action)
+	notifyIssueChange(ctx, doer, issue, hookEvent, action, nil, nil)
 }
 
 func (n *actionsNotifier) IssueChangeLabels(ctx context.Context, doer *user_model.User, issue *issues_model.Issue,
-	_, _ []*issues_model.Label,
+	addedLabels, removedLabels []*issues_model.Label,
 ) {
 	ctx = withMethod(ctx, "IssueChangeLabels")
 
@@ -201,10 +201,10 @@ func (n *actionsNotifier) IssueChangeLabels(ctx context.Context, doer *user_mode
 		hookEvent = webhook_module.HookEventPullRequestLabel
 	}
 
-	notifyIssueChange(ctx, doer, issue, hookEvent, api.HookIssueLabelUpdated)
+	notifyIssueChange(ctx, doer, issue, hookEvent, api.HookIssueLabelUpdated, addedLabels, removedLabels)
 }
 
-func notifyIssueChange(ctx context.Context, doer *user_model.User, issue *issues_model.Issue, event webhook_module.HookEventType, action api.HookIssueAction) {
+func notifyIssueChange(ctx context.Context, doer *user_model.User, issue *issues_model.Issue, event webhook_module.HookEventType, action api.HookIssueAction, addedLabels, removedLabels []*issues_model.Label) {
 	var err error
 	if err = issue.LoadRepo(ctx); err != nil {
 		log.Error("LoadRepo: %v", err)
@@ -216,34 +216,65 @@ func notifyIssueChange(ctx context.Context, doer *user_model.User, issue *issues
 		return
 	}
 
+	var addedAPILabels []*api.Label
+	if addedLabels != nil {
+		addedAPILabels = make([]*api.Label, 0, len(addedLabels))
+		for _, label := range addedLabels {
+			addedAPILabels = append(addedAPILabels, convert.ToLabel(label, issue.Repo, doer))
+		}
+	}
+
+	// Get removed labels from context if present
+	var removedAPILabels []*api.Label
+	if removedLabels != nil {
+		removedAPILabels = make([]*api.Label, 0, len(removedLabels))
+		for _, label := range removedLabels {
+			removedAPILabels = append(removedAPILabels, convert.ToLabel(label, issue.Repo, doer))
+		}
+	}
+
 	if issue.IsPull {
 		if err = issue.LoadPullRequest(ctx); err != nil {
 			log.Error("loadPullRequest: %v", err)
 			return
 		}
-		newNotifyInputFromIssue(issue, event).
-			WithDoer(doer).
-			WithPayload(&api.PullRequestPayload{
+
+		payload := &api.PullRequestPayload{
 			Action:      action,
 			Index:       issue.Index,
 			PullRequest: convert.ToAPIPullRequest(ctx, issue.PullRequest, nil),
 			Repository:  convert.ToRepo(ctx, issue.Repo, access_model.Permission{AccessMode: perm_model.AccessModeNone}),
 			Sender:      convert.ToUser(ctx, doer, nil),
-			}).
+			Changes: &api.ChangesPayload{
+				AddedLabels:   addedAPILabels,
+				RemovedLabels: removedAPILabels,
+			},
+		}
+
+		newNotifyInputFromIssue(issue, event).
+			WithDoer(doer).
+			WithPayload(payload).
 			WithPullRequest(issue.PullRequest).
 			Notify(ctx)
 		return
 	}
+
 	permission, _ := access_model.GetUserRepoPermission(ctx, issue.Repo, issue.Poster)
-	newNotifyInputFromIssue(issue, event).
-		WithDoer(doer).
-		WithPayload(&api.IssuePayload{
+	payload := &api.IssuePayload{
 		Action:     action,
 		Index:      issue.Index,
 		Issue:      convert.ToAPIIssue(ctx, doer, issue),
 		Repository: convert.ToRepo(ctx, issue.Repo, permission),
 		Sender:     convert.ToUser(ctx, doer, nil),
-		}).
+		Changes: &api.ChangesPayload{
+			AddedLabels:   addedAPILabels,
+			RemovedLabels: removedAPILabels,
+		},
+	}
+
+	newNotifyInputFromIssue(issue, event).
+		WithDoer(doer).
+		WithPayload(payload).
 		Notify(ctx)
 }