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package bot
import (
"sync"
"testing"
"time"
)
type fakeClock struct {
mu sync.Mutex
now time.Time
}
func (c *fakeClock) Now() time.Time {
c.mu.Lock()
defer c.mu.Unlock()
return c.now
}
func (c *fakeClock) Advance(d time.Duration) {
c.mu.Lock()
defer c.mu.Unlock()
c.now = c.now.Add(d)
}
func TestLimiterAllowsTheBurstThenStops(t *testing.T) {
clock := &fakeClock{now: time.Unix(1_700_000_000, 0)}
limiter := NewLimiterWith(3, time.Second, 30*time.Second, clock.Now)
for i := 0; i < 3; i++ {
if decision := limiter.Allow(1); !decision.Allowed {
t.Fatalf("request %d was refused inside the burst", i+1)
}
}
decision := limiter.Allow(1)
if decision.Allowed {
t.Fatal("the fourth request should be refused")
}
if !decision.Warn {
t.Fatal("the first refusal should warn the user")
}
if decision.RetryAfter <= 0 {
t.Fatalf("retry after = %v, want a positive hint", decision.RetryAfter)
}
}
func TestLimiterWarnsOncePerWindow(t *testing.T) {
clock := &fakeClock{now: time.Unix(1_700_000_000, 0)}
limiter := NewLimiterWith(1, time.Minute, 30*time.Second, clock.Now)
limiter.Allow(1)
if !limiter.Allow(1).Warn {
t.Fatal("the first refusal should warn")
}
if limiter.Allow(1).Warn {
t.Fatal("a second refusal inside the window should stay silent")
}
clock.Advance(31 * time.Second)
if !limiter.Allow(1).Warn {
t.Fatal("a refusal after the window should warn again")
}
}
func TestLimiterRefills(t *testing.T) {
clock := &fakeClock{now: time.Unix(1_700_000_000, 0)}
limiter := NewLimiterWith(2, time.Second, time.Minute, clock.Now)
limiter.Allow(1)
limiter.Allow(1)
if limiter.Allow(1).Allowed {
t.Fatal("the bucket should be empty")
}
clock.Advance(time.Second)
if !limiter.Allow(1).Allowed {
t.Fatal("one second should have bought one token")
}
if limiter.Allow(1).Allowed {
t.Fatal("only one token should have been refilled")
}
}
func TestLimiterNeverExceedsTheBurst(t *testing.T) {
clock := &fakeClock{now: time.Unix(1_700_000_000, 0)}
limiter := NewLimiterWith(2, time.Second, time.Minute, clock.Now)
limiter.Allow(1)
clock.Advance(time.Hour)
if !limiter.Allow(1).Allowed || !limiter.Allow(1).Allowed {
t.Fatal("the bucket should be full again")
}
if limiter.Allow(1).Allowed {
t.Fatal("an idle hour must not bank more than the burst")
}
}
func TestLimiterKeysAreIndependent(t *testing.T) {
clock := &fakeClock{now: time.Unix(1_700_000_000, 0)}
limiter := NewLimiterWith(1, time.Minute, time.Minute, clock.Now)
if !limiter.Allow(1).Allowed {
t.Fatal("first user refused")
}
if limiter.Allow(1).Allowed {
t.Fatal("first user should now be limited")
}
if !limiter.Allow(2).Allowed {
t.Fatal("one user's flood must not silence another")
}
}
func TestLimiterIsConcurrencySafe(t *testing.T) {
limiter := NewLimiterWith(100, time.Millisecond, time.Second, nil)
var wg sync.WaitGroup
for i := 0; i < 50; i++ {
wg.Add(1)
go func(key int64) {
defer wg.Done()
for j := 0; j < 20; j++ {
limiter.Allow(key % 5)
}
}(int64(i))
}
wg.Wait()
}
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