Regres: Reduce scope of regres CI emails

tests/regres/main.go

@@ -263,7 +263,7 @@ func (r *regres) run() error {
 		log.Printf("Testing change '%s'\n", change.id)
 
 		// Test the latest patchset in the change, diff against parent change.
-		msg, err := r.test(change)
+		msg, alert, err := r.test(change)
 		if err != nil {
 			log.Println(cause.Wrap(err, "Failed to test changelist '%s'", change.latest))
 			time.Sleep(time.Minute)
@@ -280,9 +280,14 @@ func (r *regres) run() error {
 			log.Printf("DRY RUN: add review to change '%v':\n%v\n", change.id, msg)
 		} else {
 			log.Printf("Posting review to '%s'\n", change.id)
+			notify := "OWNER"
+			if alert {
+				notify = "OWNER_REVIEWERS"
+			}
 			_, _, err = client.Changes.SetReview(change.id, change.latest.String(), &gerrit.ReviewInput{
 				Message: msg,
 				Tag:     "autogenerated:regress",
+				Notify:  notify,
 			})
 			if err != nil {
 				return cause.Wrap(err, "Failed to post comments on change '%s'", change.id)
@@ -292,35 +297,35 @@ func (r *regres) run() error {
 	}
 }
 
-func (r *regres) test(change *changeInfo) (string, error) {
+func (r *regres) test(change *changeInfo) (string, bool, error) {
 	latest := r.newTest(change.latest)
 	defer latest.cleanup()
 
 	if err := latest.checkout(); err != nil {
-		return "", cause.Wrap(err, "Failed to checkout '%s'", change.latest)
+		return "", true, cause.Wrap(err, "Failed to checkout '%s'", change.latest)
 	}
 
 	deqpBuild, err := r.getOrBuildDEQP(latest)
 	if err != nil {
-		return "", cause.Wrap(err, "Failed to build dEQP '%v' for change", change.id)
+		return "", true, cause.Wrap(err, "Failed to build dEQP '%v' for change", change.id)
 	}
 
 	log.Printf("Testing latest patchset for change '%s'\n", change.id)
 	latestResults, testlists, err := r.testLatest(change, latest, deqpBuild)
 	if err != nil {
-		return "", cause.Wrap(err, "Failed to test latest change of '%v'", change.id)
+		return "", true, cause.Wrap(err, "Failed to test latest change of '%v'", change.id)
 	}
 
 	log.Printf("Testing parent of change '%s'\n", change.id)
 	parentResults, err := r.testParent(change, testlists, deqpBuild)
 	if err != nil {
-		return "", cause.Wrap(err, "Failed to test parent change of '%v'", change.id)
+		return "", true, cause.Wrap(err, "Failed to test parent change of '%v'", change.id)
 	}
 
 	log.Println("Comparing latest patchset's results with parent")
-	msg := compare(parentResults, latestResults)
+	msg, alert := compare(parentResults, latestResults)
 
-	return msg, nil
+	return msg, alert, nil
 }
 
 type deqpBuild struct {
@@ -972,14 +977,15 @@ func commonFailures(results *deqp.Results) []commonFailure {
 }
 
 // compare returns a string describing all differences between two
-// deqprun.Results. This string is used as the report message posted to the
-// gerrit code review.
-func compare(old, new *deqp.Results) string {
+// deqprun.Results, and a boolean indicating that this there are differences
+// that are considered important.
+// This string is used as the report message posted to the gerrit code review.
+func compare(old, new *deqp.Results) (msg string, alert bool) {
 	if old.Error != "" {
-		return old.Error
+		return old.Error, false
 	}
 	if new.Error != "" {
-		return new.Error
+		return new.Error, true
 	}
 
 	oldStatusCounts, newStatusCounts := map[testlist.Status]int{}, map[testlist.Status]int{}
@@ -996,12 +1002,15 @@ func compare(old, new *deqp.Results) string {
 		switch {
 		case !old.Status.Failing() && new.Status.Failing():
 			broken = append(broken, test)
+			alert = true
 		case !old.Status.Passing() && new.Status.Passing():
 			fixed = append(fixed, test)
 		case old.Status != new.Status:
 			changed = append(changed, test)
+			alert = true
 		case old.Status.Failing() && new.Status.Failing():
 			failing = append(failing, test) // Still broken
+			alert = true
 		}
 		totalTests++
 		if found {
@@ -1155,7 +1164,7 @@ func compare(old, new *deqp.Results) string {
 		}
 	}
 
-	return sb.String()
+	return sb.String(), alert
 }
 
 // loadTestLists loads the full test lists from the json file.