[release-1.7] Properly export trace for duplicated "finished" event (#…

…6540)

* Properly export trace for duplicated "finished" event

Fixes an issue with duplicated finished event in which case the
following error was thrown:
knative.dev/eventing/test/upgrade/prober.(*prober).getStepNoFromMsg
...
panic: runtime error: index out of range [1] with length 0

* Define FinishedEventPrefix and reuse it

Co-authored-by: Martin Gencur <mgencur@redhat.com>

test/upgrade/prober/verify.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strings"
 	"time"
 
 	"go.uber.org/zap"
@@ -101,7 +102,11 @@ func (p *prober) Verify() (eventErrs []error, eventsSent int) {
 		} else if p.config.OnDuplicate == Error {
 			eventErrs = append(eventErrs, errors.New(t))
 		}
-		p.exportStepEventTrace(i, t)
+		if strings.HasPrefix(t, event.FinishedEventPrefix) {
+			p.exportFinishedEventTrace()
+		} else {
+			p.exportStepEventTrace(i, t)
+		}
 	}
 	return eventErrs, report.EventsSent
 }
@@ -117,19 +122,23 @@ func (p *prober) exportStepEventTrace(i int, msg string) {
 	if i > exportTraceLimit {
 		return
 	}
-	stepNo := p.getStepNoFromMsg(msg)
+	stepNo, err := p.getStepNoFromMsg(msg)
+	if err != nil {
+		p.log.Warnf("Unable to get step number: %v", err)
+		return
+	}
 	if err := p.exportTrace(p.getTraceForStepEvent(stepNo), fmt.Sprintf("step-%s.json", stepNo)); err != nil {
 		p.log.Warnf("Failed to export trace for Step event #%s: %v", stepNo, err)
 	}
 }
 
-func (p *prober) getStepNoFromMsg(message string) string {
+func (p *prober) getStepNoFromMsg(message string) (string, error) {
 	r, _ := regexp.Compile(stepEventMsgPattern)
 	matches := r.FindStringSubmatch(message)
 	if len(matches) != 2 {
-		p.log.Warnf("message does not match pattern %s: %s", stepEventMsgPattern, message)
+		return "", fmt.Errorf("message does not match pattern %s: %s", stepEventMsgPattern, message)
 	}
-	return matches[1]
+	return matches[1], nil
 }
 
 func (p *prober) getTraceForStepEvent(eventNo string) []byte {

test/upgrade/prober/wathola/event/services.go

@@ -23,6 +23,8 @@ import (
 	"knative.dev/eventing/test/upgrade/prober/wathola/config"
 )
 
+const FinishedEventPrefix = "finish event"
+
 var mutex = sync.RWMutex{}
 var lastProgressReport = time.Now()
 
@@ -93,8 +95,10 @@ func (s *stepStore) Count() int {
 func (f *finishedStore) RegisterFinished(finished *Finished) {
 	if f.received > 0 {
 		f.errors.throwDuplicated(
-			"finish event should be received only once, received %d",
-			f.received+1)
+			"%s should be received only once, received %d",
+			FinishedEventPrefix, f.received+1)
+		// We don't want to record all failures again.
+		return
 	}
 	f.received++
 	f.eventsSent = finished.EventsSent