github.com/envoyproxy/protoc-gen-validate v1.0.4: validate.E_Rules

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/protoc-gen-validate/validate.E_Rules in pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4
Demonstrate these symbols/APIs:
  - github.com/envoyproxy/protoc-gen-validate/validate.E_Rules

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:sha256:3b74e298f26840bc543473600e7cfacc424adbd3a3fe34a6ec91e9798226acd0","contract":["validate.E_Rules extension descriptor identifies field number 1071 extending google.protobuf.FieldOptions with message type validate.FieldRules","proto.SetExtension associates validate.FieldRules with descriptorpb.FieldOptions and proto.HasExtension reports presence","proto.GetExtension retrieves the configured validate.FieldRules preserving constraint values","proto.ClearExtension removes validate.E_Rules from descriptorpb.FieldOptions returning presence to false","proto.Marshal and proto.Unmarshal round-trip descriptorpb.FieldOptions preserving validate.E_Rules extension data"],"goal":"verify github.com/envoyproxy/protoc-gen-validate/validate.E_Rules in pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4","kind":"HOW","packages":["pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4"],"schemaVersion":1,"symbols":["github.com/envoyproxy/protoc-gen-validate/validate.E_Rules"]},"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/protoc-gen-validate@v1.0.4"],"schemaVersion":1,"subject":"pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4","symbols":["github.com/envoyproxy/protoc-gen-validate/validate.E_Rules"],"verifierAdapter":"golang@1"}

module example.com/validate_rules

go 1.26.6

require (
	github.com/envoyproxy/protoc-gen-validate v1.0.4
	google.golang.org/protobuf v1.32.0
)

require golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect

github.com/envoyproxy/protoc-gen-validate v1.0.4 h1:gVPz/FMfvh57HdSJQyvBtF00j8JU4zdyUgIUNhlgg0A=
github.com/envoyproxy/protoc-gen-validate v1.0.4/go.mod h1:qys6tmnRsYrQqIhm2bvKZH4Blx/1gTIZ2UKVY1M+Yew=
github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
google.golang.org/protobuf v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

package main

import (
	"fmt"

	"github.com/envoyproxy/protoc-gen-validate/validate"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/descriptorpb"
)

func main() {
	opts := &descriptorpb.FieldOptions{}

	rules := &validate.FieldRules{
		Type: &validate.FieldRules_String_{
			String_: &validate.StringRules{
				MinLen: proto.Uint64(1),
				MaxLen: proto.Uint64(64),
			},
		},
	}

	proto.SetExtension(opts, validate.E_Rules, rules)

	hasRules := proto.HasExtension(opts, validate.E_Rules)
	retrieved := proto.GetExtension(opts, validate.E_Rules).(*validate.FieldRules)

	fmt.Printf("Has validation rules: %v\n", hasRules)
	fmt.Printf("String rule min length: %d\n", retrieved.GetString_().GetMinLen())
	fmt.Printf("String rule max length: %d\n", retrieved.GetString_().GetMaxLen())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/envoyproxy/protoc-gen-validate/validate.E_Rules in pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/envoyproxy/protoc-gen-validate@v1.0.4"
  ],
  "symbols": [
    "github.com/envoyproxy/protoc-gen-validate/validate.E_Rules"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/envoyproxy/protoc-gen-validate/validate"
	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/types/descriptorpb"
)

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

func runTests() error {
	// 1. validate.E_Rules extension descriptor identifies field number 1071 extending google.protobuf.FieldOptions with message type validate.FieldRules
	typeDesc := validate.E_Rules.TypeDescriptor()
	if typeDesc.Number() != 1071 {
		return fmt.Errorf("expected field number 1071, got %d", typeDesc.Number())
	}
	if string(typeDesc.ContainingMessage().FullName()) != "google.protobuf.FieldOptions" {
		return fmt.Errorf("expected extended message google.protobuf.FieldOptions, got %s", typeDesc.ContainingMessage().FullName())
	}
	if typeDesc.Message() == nil || string(typeDesc.Message().FullName()) != "validate.FieldRules" {
		return fmt.Errorf("expected message type validate.FieldRules, got %v", typeDesc.Message())
	}

	// 2. proto.SetExtension associates validate.FieldRules with descriptorpb.FieldOptions and proto.HasExtension reports presence
	opts := &descriptorpb.FieldOptions{}
	if proto.HasExtension(opts, validate.E_Rules) {
		return fmt.Errorf("expected empty FieldOptions to not have validate.E_Rules")
	}

	rules := &validate.FieldRules{
		Type: &validate.FieldRules_String_{
			String_: &validate.StringRules{
				MinLen:  proto.Uint64(3),
				MaxLen:  proto.Uint64(20),
				Pattern: proto.String("^[a-z0-9_-]+$"),
			},
		},
	}
	proto.SetExtension(opts, validate.E_Rules, rules)
	if !proto.HasExtension(opts, validate.E_Rules) {
		return fmt.Errorf("expected FieldOptions to have validate.E_Rules after proto.SetExtension")
	}

	// 3. proto.GetExtension retrieves the configured validate.FieldRules preserving constraint values
	rawExt := proto.GetExtension(opts, validate.E_Rules)
	gotRules, ok := rawExt.(*validate.FieldRules)
	if !ok {
		return fmt.Errorf("expected *validate.FieldRules from GetExtension, got %T", rawExt)
	}
	strRules := gotRules.GetString_()
	if strRules == nil {
		return fmt.Errorf("expected non-nil StringRules in retrieved FieldRules")
	}
	if strRules.GetMinLen() != 3 {
		return fmt.Errorf("expected min length 3, got %d", strRules.GetMinLen())
	}
	if strRules.GetMaxLen() != 20 {
		return fmt.Errorf("expected max length 20, got %d", strRules.GetMaxLen())
	}
	if strRules.GetPattern() != "^[a-z0-9_-]+$" {
		return fmt.Errorf("expected pattern ^[a-z0-9_-]+$, got %s", strRules.GetPattern())
	}

	// 4. proto.ClearExtension removes validate.E_Rules from descriptorpb.FieldOptions returning presence to false
	proto.ClearExtension(opts, validate.E_Rules)
	if proto.HasExtension(opts, validate.E_Rules) {
		return fmt.Errorf("expected validate.E_Rules to be removed after proto.ClearExtension")
	}

	// 5. proto.Marshal and proto.Unmarshal round-trip descriptorpb.FieldOptions preserving validate.E_Rules extension data
	optsToMarshal := &descriptorpb.FieldOptions{}
	proto.SetExtension(optsToMarshal, validate.E_Rules, rules)

	marshaled, err := proto.Marshal(optsToMarshal)
	if err != nil {
		return fmt.Errorf("proto.Marshal failed: %w", err)
	}

	unmarshaledOpts := &descriptorpb.FieldOptions{}
	if err := proto.Unmarshal(marshaled, unmarshaledOpts); err != nil {
		return fmt.Errorf("proto.Unmarshal failed: %w", err)
	}
	if !proto.HasExtension(unmarshaledOpts, validate.E_Rules) {
		return fmt.Errorf("expected unmarshaled FieldOptions to retain validate.E_Rules extension")
	}
	roundTripExt := proto.GetExtension(unmarshaledOpts, validate.E_Rules).(*validate.FieldRules)
	if roundTripExt.GetString_().GetMinLen() != 3 || roundTripExt.GetString_().GetMaxLen() != 20 {
		return fmt.Errorf("unmarshaled rules constraints do not match original: %+v", roundTripExt.GetString_())
	}

	return nil
}