fix: harden websocket heartbeat under load

server/hdl_websock_config_test.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestConfigureWSHeartbeat(t *testing.T) {
+	originalPing, originalPong := pingPeriod, pongWait
+	t.Cleanup(func() {
+		pingPeriod, pongWait = originalPing, originalPong
+	})
+
+	if err := configureWSHeartbeat(20, 120); err != nil {
+		t.Fatal(err)
+	}
+	if pingPeriod != 20*time.Second || pongWait != 120*time.Second {
+		t.Fatalf("heartbeat ping=%s pong=%s", pingPeriod, pongWait)
+	}
+	if err := configureWSHeartbeat(90, 90); err == nil {
+		t.Fatal("expected invalid heartbeat configuration to fail")
+	}
+	if err := configureWSHeartbeat(0, 0); err != nil {
+		t.Fatal(err)
+	}
+	if pingPeriod != defaultWSPingPeriod || pongWait != defaultWSPongWait {
+		t.Fatalf("default heartbeat ping=%s pong=%s", pingPeriod, pongWait)
+	}
+}