Wait for file playback workers before restart

fileplayback/player_regression_test.go

@@ -0,0 +1,24 @@
+package fileplayback
+
+import (
+	"testing"
+	"time"
+)
+
+// Regression: Stop returned before the previous ffmpeg worker exited, allowing
+// a subsequent PlayFile to replace shared state while old audio was still sent.
+func TestStopWaitsForPlaybackWorker(t *testing.T) {
+	p := &Player{playing: true, stopChan: make(chan struct{})}
+	p.wg.Add(1)
+	done := make(chan error, 1)
+	go func() { done <- p.Stop() }()
+	select {
+	case <-done:
+		t.Fatal("Stop returned before playback worker ended")
+	case <-time.After(20 * time.Millisecond):
+	}
+	p.wg.Done()
+	if err := <-done; err != nil {
+		t.Fatal(err)
+	}
+}