Handles branch delete event on github

When a branch is deleted via repository UI, a push event
is triggered and the payload will have a zero hash value

Hence, this patch handles the deletion of branch deletion and
returns early from ParsePayload function without further
processing which in turn also avoids unnecessary log noise

Signed-off-by: PuneetPunamiya <ppunamiy@redhat.com>

Author: PuneetPunamiya

pkg/provider/github/parse_payload.go

@@ -259,6 +259,16 @@ func (v *Provider) processEvent(ctx context.Context, event *info.Event, eventInt
 		if gitEvent.GetRepo() == nil {
 			return nil, errors.New("error parsing payload the repository should not be nil")
 		}
+
+		// When a branch is deleted via repository UI, it triggers a push event.
+		// However, Pipelines as Code does not support handling branch delete events,
+		// so we return an error here to indicate this unsupported operation.
+		if gitEvent.After != nil {
+			if provider.IsZeroSHA(*gitEvent.After) {
+				return nil, fmt.Errorf("branch %s has been deleted, exiting", gitEvent.GetRef())
+			}
+		}
+
 		processedEvent.Organization = gitEvent.GetRepo().GetOwner().GetLogin()
 		processedEvent.Repository = gitEvent.GetRepo().GetName()
 		processedEvent.DefaultBranch = gitEvent.GetRepo().GetDefaultBranch()

pkg/provider/github/parse_payload_test.go

@@ -204,6 +204,20 @@ func TestParsePayLoad(t *testing.T) {
 			payloadEventStruct: github.PushEvent{},
 			wantErrString:      "error parsing payload the repository should not be nil",
 		},
+		{
+			name:          "branch/deleted",
+			eventType:     "push",
+			triggerTarget: triggertype.Push.String(),
+			payloadEventStruct: github.PushEvent{
+				Repo: &github.PushEventRepository{
+					Owner: &github.User{Login: github.Ptr("foo")},
+					Name:  github.Ptr("pushRepo"),
+				},
+				Ref:   github.Ptr("test"),
+				After: github.Ptr("0000000000000000000000000000000000000000"),
+			},
+			wantErrString: "branch test has been deleted, exiting",
+		},
 		{
 			// specific run from a check_suite
 			name:          "good/rerequest check_run on pull request",

pkg/provider/provider.go

@@ -186,3 +186,7 @@ func GetCheckName(status StatusOpts, pacopts *info.PacOpts) string {
 	}
 	return status.OriginalPipelineRunName
 }
+
+func IsZeroSHA(sha string) bool {
+	return sha == "0000000000000000000000000000000000000000"
+}