Add healthcheck code

relay/healthcheck/receiver_test.go

@@ -0,0 +1,42 @@
+package healthcheck
+
+import (
+	"testing"
+	"time"
+)
+
+func TestNewReceiver(t *testing.T) {
+	heartbeatTimeout = 5 * time.Second
+	r := NewReceiver()
+
+	select {
+	case <-r.OnTimeout:
+		t.Error("unexpected timeout")
+	case <-time.After(1 * time.Second):
+
+	}
+}
+
+func TestNewReceiverNotReceive(t *testing.T) {
+	heartbeatTimeout = 1 * time.Second
+	r := NewReceiver()
+
+	select {
+	case <-r.OnTimeout:
+	case <-time.After(2 * time.Second):
+		t.Error("timeout not received")
+	}
+}
+
+func TestNewReceiverAck(t *testing.T) {
+	heartbeatTimeout = 2 * time.Second
+	r := NewReceiver()
+
+	r.Heartbeat()
+
+	select {
+	case <-r.OnTimeout:
+		t.Error("unexpected timeout")
+	case <-time.After(3 * time.Second):
+	}
+}