1 files changed, 48 insertions, 0 deletions
diff --git a/internal/streamrow/row_test.go b/internal/streamrow/row_test.go
new file mode 100644
index 0000000..729ba94
--- /dev/null
+++ b/internal/streamrow/row_test.go
@@ -0,0 +1,48 @@
+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)
+	}
+}