antidrift/internal/harness/async_test.go

package harness

import (
	"context"
	"sync"
	"testing"
	"time"
)

func TestAsyncRunAppliesAndNotifies(t *testing.T) {
	var mu sync.Mutex
	notified := make(chan struct{}, 1)
	a := NewAsync(&mu, func() { notified <- struct{}{} })

	var applied bool
	a.Run(time.Second,
		func(ctx context.Context) {},
		func() bool { return false },
		func() { applied = true },
	)
	select {
	case <-notified:
	case <-time.After(time.Second):
		t.Fatal("notify never fired")
	}
	mu.Lock()
	defer mu.Unlock()
	if !applied {
		t.Fatal("apply did not run")
	}
}

func TestAsyncRunStaleSkipsApplyAndNotify(t *testing.T) {
	var mu sync.Mutex
	a := NewAsync(&mu, func() { t.Fatal("notify fired on stale result") })
	done := make(chan struct{})
	a.Run(time.Second,
		func(ctx context.Context) {},
		func() bool { close(done); return true },
		func() { t.Fatal("apply ran on stale result") },
	)
	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("stale guard never evaluated")
	}
	time.Sleep(20 * time.Millisecond) // allow a wrongful notify to surface
}