Join capture worker before stopping OpenAL

gumble/gumbleopenal/stream_regression_test.go

@@ -4,6 +4,22 @@ import "testing"
 
 // Regression: audio cleanup could send a final render command after Destroy
 // had closed renderCh, panicking instead of safely discarding that work.
+// Regression: StopSource returned before the capture worker ended, allowing
+// Destroy to close the device while that worker still used it.
+func TestStopSourceWaitsForWorker(t *testing.T) {
+	stop, done := make(chan bool), make(chan struct{})
+	s := &Stream{sourceStop: stop, sourceDone: done}
+	returned := make(chan struct{})
+	go func() { _ = s.StopSource(); close(returned) }()
+	select {
+	case <-returned:
+		t.Fatal("StopSource returned before worker")
+	default:
+	}
+	close(done)
+	<-returned
+}
+
 func TestRenderRejectsWorkAfterShutdown(t *testing.T) {
 	s := &Stream{renderClosed: true}
 	called := false