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package streamrow
import (
"sync"
"testing"
)
func TestSequencerStartsAfterSeed(t *testing.T) {
seq := NewSequencer(41)
if got, want := seq.Next(), uint64(42); got != want {
t.Fatalf("first Next() = %d, want %d", got, want)
}
if got, want := seq.Next(), uint64(43); got != want {
t.Fatalf("second Next() = %d, want %d", got, want)
}
}
func TestSequencerIsMonotonicUnderConcurrency(t *testing.T) {
seq := NewSequencer(0)
const workers = 8
const perWorker = 64
got := make(chan uint64, workers*perWorker)
var wg sync.WaitGroup
for i := 0; i < workers; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for j := 0; j < perWorker; j++ {
got <- seq.Next()
}
}()
}
wg.Wait()
close(got)
seen := make(map[uint64]struct{}, workers*perWorker)
for n := range got {
if _, ok := seen[n]; ok {
t.Fatalf("duplicate sequence number %d", n)
}
seen[n] = struct{}{}
}
if got, want := len(seen), workers*perWorker; got != want {
t.Fatalf("unique sequence count = %d, want %d", got, want)
}
}
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