TestSummaryDecay() failed

[Jumpmanhere]

No description provided.

[Jumpmanhere]

When I run the TestSummaryDecay() function of the summary_test.go file every 300 times, there are normally a few times failed.
    Does anyone else encounter this problem?  
    Actually, I'm not so sure about the test logic --- how do we decide the number 20 here as the condition "math.abs(got - want) > 20" 
    and why assign the AgeBucket with the value 10 in this test?

func TestSummaryDecay(t *testing.T) {
if testing.Short() {
t.Skip("Skipping test in short mode.")
// More because it depends on timing than because it is particularly long...
}

sum := NewSummary(SummaryOpts{
	Name:       "test_summary",
	Help:       "helpless",
	MaxAge:     100 * time.Millisecond,
	Objectives: map[float64]float64{0.1: 0.001},
	AgeBuckets: 10,
})

m := &dto.Metric{}
i := 0
tick := time.NewTicker(time.Millisecond)
for range tick.C {
	i++
	sum.Observe(float64(i))
	if i%10 == 0 {
		sum.Write(m)
		if got, want := *m.Summary.Quantile[0].Value, math.Max(float64(i)/10, float64(i-90)); math.Abs(got-want) > 20 {
			t.Errorf("%d. got %f, want %f", i, got, want)
		}
		m.Reset()
	}
	if i >= 1000 {
		break
	}
}
tick.Stop()
// Wait for MaxAge without observations and make sure quantiles are NaN.
time.Sleep(100 * time.Millisecond)
sum.Write(m)
if got := *m.Summary.Quantile[0].Value; !math.IsNaN(got) {
	t.Errorf("got %f, want NaN after expiration", got)
}

}

[bwplotka]

It's indeed flaky - it's covered in #765

Help welcome! - closing this one as dup.

[RubanChristian]

Try Mar