Add healthcheck code

relay/healthcheck/sender_test.go

@@ -0,0 +1,66 @@
+package healthcheck
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestNewHealthPeriod(t *testing.T) {
+	// override the health check interval to speed up the test
+	healthCheckInterval = 1 * time.Second
+	healthCheckTimeout = 100 * time.Millisecond
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	hc := NewSender(ctx)
+
+	iterations := 0
+	for i := 0; i < 3; i++ {
+		select {
+		case <-hc.HealthCheck:
+			iterations++
+			hc.OnHCResponse()
+		case <-hc.Timeout:
+			t.Fatalf("health check is timed out")
+		case <-time.After(healthCheckInterval + 100*time.Millisecond):
+			t.Fatalf("health check not received")
+		}
+	}
+}
+
+func TestNewHealthFailed(t *testing.T) {
+	// override the health check interval to speed up the test
+	healthCheckInterval = 1 * time.Second
+	healthCheckTimeout = 500 * time.Millisecond
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	hc := NewSender(ctx)
+
+	select {
+	case <-hc.Timeout:
+	case <-time.After(healthCheckInterval + healthCheckTimeout + 100*time.Millisecond):
+		t.Fatalf("health check is not timed out")
+	}
+}
+
+func TestNewHealthcheckStop(t *testing.T) {
+
+	ctx, cancel := context.WithCancel(context.Background())
+	hc := NewSender(ctx)
+
+	time.Sleep(1 * time.Second)
+	cancel()
+
+	select {
+	case <-hc.HealthCheck:
+		t.Fatalf("is not closed")
+	case <-hc.Timeout:
+		t.Fatalf("is not closed")
+	case <-ctx.Done():
+		// expected
+	case <-time.After(1 * time.Second):
+		t.Fatalf("is not exited")
+	}
+}