switch to iterators and client polling

pkg/client/client_test.go

@@ -144,21 +144,21 @@ func TestClientWingbitsEndpoints(t *testing.T) {
 	}
 }
 
-func TestStreamAircraft(t *testing.T) {
+func TestPollAircraft(t *testing.T) {
 	c := newTestClient(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
+	ctx := t.Context()
 
-	ch := c.StreamAircraft(ctx, time.Hour)
-	select {
-	case u := <-ch:
-		if u.Err != nil || u.Value == nil || len(u.Value.Aircraft) == 0 {
-			t.Fatalf("first update bad: %v", u.Err)
+	// A long interval means the iterator only yields its immediate first sample;
+	// breaking out must stop polling cleanly (no goroutine, no hang).
+	var got int
+	for report, err := range c.PollAircraft(ctx, time.Hour, readsb.WithPosition()) {
+		if err != nil || report == nil || len(report.Aircraft) == 0 {
+			t.Fatalf("first poll bad: %v", err)
 		}
-	case <-time.After(5 * time.Second):
-		t.Fatal("no first update")
+		got++
+		break
 	}
-	cancel()
-	for range ch { // channel must drain and close after cancellation
+	if got != 1 {
+		t.Fatalf("expected exactly one sample before break, got %d", got)
 	}
 }