Create scaffolding of ddl-simulator

Implement global server as control plane

Implement device to get their info from global server and connect each
others

pkg/leader/tree_test.go

@@ -0,0 +1,24 @@
+package leader_test
+
+import (
+	"fmt"
+	"testing"
+
+	yaml "gopkg.in/yaml.v3"
+
+	"git.pengzhan.dev/ddp-simulator/pkg/leader"
+)
+
+func TestTree(t *testing.T) {
+	l4 := leader.NewTreeNode("4", nil)
+	l3 := leader.NewTreeNode("3", nil)
+	l2 := leader.NewTreeNode("2", nil)
+	l1 := leader.NewTreeNode("1", []leader.TreeNode{*l4, *l3})
+	l0 := leader.NewTreeNode("0", []leader.TreeNode{*l1, *l2})
+
+	yamlData, err := yaml.Marshal(l0)
+	if err != nil {
+		t.Fatalf("failed to marshal yaml: %v", err)
+	}
+	fmt.Println(string(yamlData))
+}