Code refactoring for panic: send on closed channel

pkg/core/track_test.go

@@ -0,0 +1,53 @@
+package core
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSenser(t *testing.T) {
+	recv := make(chan *Packet) // blocking receiver
+
+	sender := NewSender(nil, &Codec{})
+	sender.Output = func(packet *Packet) {
+		recv <- packet
+	}
+	require.Equal(t, "new", sender.State())
+
+	sender.Start()
+	require.Equal(t, "connected", sender.State())
+
+	sender.Input(&Packet{})
+	sender.Input(&Packet{})
+
+	require.Equal(t, 2, sender.Packets)
+	require.Equal(t, 0, sender.Drops)
+
+	// important to read one before close
+	// because goroutine in Start() can run with nil chan
+	// it's OK in real life, but bad for test
+	_, ok := <-recv
+	require.True(t, ok)
+
+	sender.Close()
+	require.Equal(t, "closed", sender.State())
+
+	sender.Input(&Packet{})
+
+	require.Equal(t, 2, sender.Packets)
+	require.Equal(t, 1, sender.Drops)
+
+	// read 2nd
+	_, ok = <-recv
+	require.True(t, ok)
+
+	// read 3rd
+	select {
+	case <-recv:
+		ok = true
+	default:
+		ok = false
+	}
+	require.False(t, ok)
+}