github.com/envoyproxy/go-control-plane/envoy v1.36.0: v3.Cluster_ROUND_ROBIN

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0
Demonstrate these symbols/APIs:
  - github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:fa2798d650626d945a495d8146143666ff1560994b34ea793abe5ed857b64c46","contract":["Cluster_ROUND_ROBIN is defined as Cluster_LbPolicy with string representation ROUND_ROBIN and maps in enum tables","Cluster initializes with LbPolicy Cluster_ROUND_ROBIN and GetLbPolicy returns ROUND_ROBIN"],"goal":"verify github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0","kind":"HOW","packages":["pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0"],"schemaVersion":1,"symbols":["github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0","symbols":["github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN"],"verifierAdapter":"golang@1"}

module sample

go 1.23.0

require github.com/envoyproxy/go-control-plane/envoy v1.36.0

require (
	github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 // indirect
	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
	google.golang.org/protobuf v1.36.10 // indirect
)

github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443 h1:aQ3y1lwWyqYPiWZThqv1aFbZMiM9vblcSArJRf2Irls=
github.com/cncf/xds/go v0.0.0-20250501225837-2ac532fd4443/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
github.com/envoyproxy/go-control-plane/envoy v1.36.0 h1:yg/JjO5E7ubRyKX3m07GF3reDNEnfOboJ0QySbH736g=
github.com/envoyproxy/go-control-plane/envoy v1.36.0/go.mod h1:ty89S1YCCVruQAm9OtKeEkQLTb+Lkz0k8v9W0Oxsv98=
github.com/envoyproxy/protoc-gen-validate v1.2.1 h1:DEo3O99U8j4hBFwbJfrz9VtgcDfUKS7KJ7spH3d86P8=
github.com/envoyproxy/protoc-gen-validate v1.2.1/go.mod h1:d/C80l/jxXLdfEIhX1W2TmLfsJ31lvEjwamM4DxlWXU=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 h1:GFCKgmp0tecUJ0sJuv4pzYCqS9+RGSn52M3FUwPs+uo=
github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=

{
  "schemaVersion": 1,
  "goal": "verify github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN in pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/envoyproxy/go-control-plane/envoy@v1.36.0"
  ],
  "symbols": [
    "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3.Cluster_ROUND_ROBIN"
  ]
}

package main

import (
	"fmt"
	"os"

	clusterv3 "github.com/envoyproxy/go-control-plane/envoy/config/cluster/v3"
)

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract tests passed successfully.")
}

func runTests() error {
	// 1. Cluster_ROUND_ROBIN is defined as Cluster_LbPolicy with string name "ROUND_ROBIN"
	lbPolicy := clusterv3.Cluster_ROUND_ROBIN
	if lbPolicy.String() != "ROUND_ROBIN" {
		return fmt.Errorf("unexpected string representation: got %q, want %q", lbPolicy.String(), "ROUND_ROBIN")
	}

	// 2. Cluster_ROUND_ROBIN is mapped in Cluster_LbPolicy_value and Cluster_LbPolicy_name
	val, ok := clusterv3.Cluster_LbPolicy_value["ROUND_ROBIN"]
	if !ok {
		return fmt.Errorf("ROUND_ROBIN not found in Cluster_LbPolicy_value")
	}
	if clusterv3.Cluster_LbPolicy(val) != clusterv3.Cluster_ROUND_ROBIN {
		return fmt.Errorf("Cluster_LbPolicy_value mismatch: got %v, want %v", val, clusterv3.Cluster_ROUND_ROBIN)
	}
	if name, ok := clusterv3.Cluster_LbPolicy_name[int32(clusterv3.Cluster_ROUND_ROBIN)]; !ok || name != "ROUND_ROBIN" {
		return fmt.Errorf("Cluster_LbPolicy_name mismatch: got %q, want %q", name, "ROUND_ROBIN")
	}

	// 3. Cluster initializes with LbPolicy Cluster_ROUND_ROBIN and GetLbPolicy returns it
	cluster := &clusterv3.Cluster{
		Name:     "service_cluster",
		LbPolicy: clusterv3.Cluster_ROUND_ROBIN,
	}
	if cluster.GetLbPolicy() != clusterv3.Cluster_ROUND_ROBIN {
		return fmt.Errorf("GetLbPolicy mismatch: got %v, want %v", cluster.GetLbPolicy(), clusterv3.Cluster_ROUND_ROBIN)
	}

	return nil
}