Alerting: tests for ticker (#47986)

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Yuriy Tseretyan 2022-04-21 14:58:05 -04:00 committed by GitHub
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@ -1,121 +1,119 @@
package alerting
// import (
// "testing"
// "time"
//
// "github.com/benbjohnson/clock"
// )
//
// func inspectTick(tick time.Time, last time.Time, offset time.Duration, t *testing.T) {
// if !tick.Equal(last.Add(time.Duration(1) * time.Second)) {
// t.Fatalf("expected a tick 1 second more than prev, %s. got: %s", last, tick)
// }
// }
//
// returns the new last tick seen
// func assertAdvanceUntil(ticker *Ticker, last, desiredLast time.Time, offset, wait time.Duration, t *testing.T) time.Time {
// for {
// select {
// case tick := <-ticker.C:
// inspectTick(tick, last, offset, t)
// last = tick
// case <-time.NewTimer(wait).C:
// if last.Before(desiredLast) {
// t.Fatalf("waited %s for ticker to advance to %s, but only went up to %s", wait, desiredLast, last)
// }
// if last.After(desiredLast) {
// t.Fatalf("timer advanced too far. should only have gone up to %s, but it went up to %s", desiredLast, last)
// }
// return last
// }
// }
// }
//
// func assertNoAdvance(ticker *Ticker, desiredLast time.Time, wait time.Duration, t *testing.T) {
// for {
// select {
// case tick := <-ticker.C:
// t.Fatalf("timer should have stayed at %s, instead it advanced to %s", desiredLast, tick)
// case <-time.NewTimer(wait).C:
// return
// }
// }
// }
//
// func TestTickerRetro1Hour(t *testing.T) {
// offset := time.Duration(10) * time.Second
// last := time.Unix(0, 0)
// mock := clock.NewMock()
// mock.Add(time.Duration(1) * time.Hour)
// desiredLast := mock.Now().Add(-offset)
// ticker := NewTicker(last, offset, mock)
//
// last = assertAdvanceUntil(ticker, last, desiredLast, offset, time.Duration(10)*time.Millisecond, t)
// assertNoAdvance(ticker, last, time.Duration(500)*time.Millisecond, t)
//
// }
//
// func TestAdvanceWithUpdateOffset(t *testing.T) {
// offset := time.Duration(10) * time.Second
// last := time.Unix(0, 0)
// mock := clock.NewMock()
// mock.Add(time.Duration(1) * time.Hour)
// desiredLast := mock.Now().Add(-offset)
// ticker := NewTicker(last, offset, mock)
//
// last = assertAdvanceUntil(ticker, last, desiredLast, offset, time.Duration(10)*time.Millisecond, t)
// assertNoAdvance(ticker, last, time.Duration(500)*time.Millisecond, t)
//
// // lowering offset should see a few more ticks
// offset = time.Duration(5) * time.Second
// ticker.updateOffset(offset)
// desiredLast = mock.Now().Add(-offset)
// last = assertAdvanceUntil(ticker, last, desiredLast, offset, time.Duration(9)*time.Millisecond, t)
// assertNoAdvance(ticker, last, time.Duration(500)*time.Millisecond, t)
//
// // advancing clock should see even more ticks
// mock.Add(time.Duration(1) * time.Hour)
// desiredLast = mock.Now().Add(-offset)
// last = assertAdvanceUntil(ticker, last, desiredLast, offset, time.Duration(8)*time.Millisecond, t)
// assertNoAdvance(ticker, last, time.Duration(500)*time.Millisecond, t)
//
// }
//
// func getCase(lastSeconds, offsetSeconds int) (time.Time, time.Duration) {
// last := time.Unix(int64(lastSeconds), 0)
// offset := time.Duration(offsetSeconds) * time.Second
// return last, offset
// }
//
// func TestTickerNoAdvance(t *testing.T) {
//
// // it's 00:01:00 now. what are some cases where we don't want the ticker to advance?
// mock := clock.NewMock()
// mock.Add(time.Duration(60) * time.Second)
//
// type Case struct {
// last int
// offset int
// }
//
// // note that some cases add up to now, others go into the future
// cases := []Case{
// {50, 10},
// {50, 30},
// {59, 1},
// {59, 10},
// {59, 30},
// {60, 1},
// {60, 10},
// {60, 30},
// {90, 1},
// {90, 10},
// {90, 30},
// }
// for _, c := range cases {
// last, offset := getCase(c.last, c.offset)
// ticker := NewTicker(last, offset, mock)
// assertNoAdvance(ticker, last, time.Duration(500)*time.Millisecond, t)
// }
// }
import (
"context"
"fmt"
"math/rand"
"sync"
"testing"
"time"
"github.com/benbjohnson/clock"
"github.com/stretchr/testify/require"
)
func TestTicker(t *testing.T) {
readChanOrFail := func(t *testing.T, ctx context.Context, c chan time.Time) time.Time {
t.Helper()
select {
case tick := <-c:
return tick
case <-ctx.Done():
require.Failf(t, fmt.Sprintf("%v", ctx.Err()), "timeout reading the channel")
default:
require.Failf(t, "channel is empty but it should have a tick", "")
}
return time.Time{}
}
t.Run("should not drop ticks", func(t *testing.T) {
clk := clock.NewMock()
intervalSec := rand.Int63n(100) + 10
interval := time.Duration(intervalSec) * time.Second
last := clk.Now()
ticker := NewTicker(last, 0, clk, intervalSec)
ticks := rand.Intn(9) + 1
jitter := rand.Int63n(int64(interval) - 1)
clk.Add(time.Duration(ticks)*interval + time.Duration(jitter))
w := sync.WaitGroup{}
w.Add(1)
regTicks := make([]time.Time, 0, ticks)
go func() {
for timestamp := range ticker.C {
regTicks = append(regTicks, timestamp)
if len(regTicks) == ticks {
w.Done()
}
}
}()
w.Wait()
require.Len(t, regTicks, ticks)
t.Run("ticks should monotonically increase", func(t *testing.T) {
for i := 1; i < len(regTicks); i++ {
previous := regTicks[i-1]
current := regTicks[i]
require.Equal(t, interval, current.Sub(previous))
}
})
})
t.Run("should not put anything to channel until it's time", func(t *testing.T) {
clk := clock.NewMock()
intervalSec := rand.Int63n(9) + 1
interval := time.Duration(intervalSec) * time.Second
last := clk.Now()
ticker := NewTicker(last, 0, clk, intervalSec)
expectedTick := clk.Now().Add(interval)
for {
require.Empty(t, ticker.C)
clk.Add(time.Duration(rand.Int31n(500)+100) * time.Millisecond)
if clk.Now().After(expectedTick) {
break
}
}
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
t.Cleanup(func() {
cancel()
})
actual := readChanOrFail(t, ctx, ticker.C)
require.Equal(t, expectedTick, actual)
})
t.Run("should put the tick in the channel immediately if it is behind", func(t *testing.T) {
clk := clock.NewMock()
intervalSec := rand.Int63n(9) + 1
interval := time.Duration(intervalSec) * time.Second
last := clk.Now()
ticker := NewTicker(last, 0, clk, intervalSec)
// We can expect the first tick to be at a consistent interval. Take a snapshot of the clock now, before we advance it.
expectedTick := clk.Now().Add(interval)
require.Empty(t, ticker.C)
clk.Add(interval) // advance the clock by the interval to make the ticker tick the first time.
clk.Add(interval) // advance the clock by the interval to make the ticker tick the second time.
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
t.Cleanup(func() {
cancel()
})
// Irregardless of wall time, the first tick should be initial clock + interval.
actual1 := readChanOrFail(t, ctx, ticker.C)
require.Equal(t, expectedTick, actual1)
var actual2 time.Time
require.Eventually(t, func() bool {
actual2 = readChanOrFail(t, ctx, ticker.C)
return true
}, time.Second, 10*time.Millisecond)
// Similarly, the second tick should be last tick + interval irregardless of wall time.
require.Equal(t, expectedTick.Add(interval), actual2)
})
}