accounting: fix total duration calculation

Fixes: #3498

fs/accounting/stats.go

@@ -138,7 +138,7 @@ func (s *StatsInfo) totalDuration() time.Duration {
 	var total time.Duration
 	var i, j = 0, 1
 	for i < len(timeRanges) {
-		if j < len(timeRanges)-1 {
+		if j < len(timeRanges) {
 			if timeRanges[j].start.Before(timeRanges[i].end) {
 				if timeRanges[i].end.Before(timeRanges[j].end) {
 					timeRanges[i].end = timeRanges[j].end

fs/accounting/stats_test.go

@@ -130,10 +130,40 @@ func TestStatsError(t *testing.T) {
 }
 
 func TestStatsTotalDuration(t *testing.T) {
-	time1 := time.Now().Add(-40 * time.Second)
+	startTime := time.Now()
+	time1 := startTime.Add(-40 * time.Second)
 	time2 := time1.Add(10 * time.Second)
 	time3 := time2.Add(10 * time.Second)
 	time4 := time3.Add(10 * time.Second)
+
+	t.Run("Single completed transfer", func(t *testing.T) {
+		s := NewStats()
+		s.AddTransfer(&Transfer{
+			startedAt:   time1,
+			completedAt: time2,
+		})
+
+		s.mu.Lock()
+		total := s.totalDuration()
+		s.mu.Unlock()
+
+		assert.Equal(t, 10*time.Second, total)
+	})
+
+	t.Run("Single uncompleted transfer", func(t *testing.T) {
+		s := NewStats()
+		s.AddTransfer(&Transfer{
+			startedAt: time1,
+		})
+
+		s.mu.Lock()
+		total := s.totalDuration()
+		s.mu.Unlock()
+
+		assert.Equal(t, time.Since(time1)/time.Second, total/time.Second)
+	})
+
+	t.Run("Overlapping without ending", func(t *testing.T) {
 		s := NewStats()
 		s.AddTransfer(&Transfer{
 			startedAt:   time2,
@@ -161,21 +191,29 @@ func TestStatsTotalDuration(t *testing.T) {
 		total := s.totalDuration()
 		s.mu.Unlock()
 
-	assert.True(t, 30*time.Second < total && total < 31*time.Second, total)
+		assert.Equal(t, time.Duration(30), total/time.Second)
-}
+	})
 
-func TestStatsTotalDuration2(t *testing.T) {
+	t.Run("Mixed completed and uncompleted transfers", func(t *testing.T) {
-	time1 := time.Now().Add(-40 * time.Second)
-	time2 := time1.Add(10 * time.Second)
 		s := NewStats()
 		s.AddTransfer(&Transfer{
 			startedAt:   time1,
 			completedAt: time2,
 		})
+		s.AddTransfer(&Transfer{
+			startedAt: time2,
+		})
+		s.AddTransfer(&Transfer{
+			startedAt: time3,
+		})
+		s.AddTransfer(&Transfer{
+			startedAt: time3,
+		})
 
 		s.mu.Lock()
 		total := s.totalDuration()
 		s.mu.Unlock()
 
-	assert.Equal(t, 10*time.Second, total)
+		assert.Equal(t, startTime.Sub(time1)/time.Second, total/time.Second)
+	})
 }