github.com/jackc/pgx/v5 v5.10.0: pgproto3.Terminate

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/jackc/pgx/v5/pgproto3.Terminate in pkg:golang/github.com/jackc/pgx/v5@v5.10.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/jackc/pgx/v5@v5.10.0
Demonstrate these symbols/APIs:
  - github.com/jackc/pgx/v5/pgproto3.Terminate

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:c1e051f408f90e1fd42835e65f320e8dae6566c87fcb50c3e378f1fc951b396c","contract":["pgproto3.Terminate implements pgproto3.FrontendMessage","Terminate.Encode appends the 5-byte frontend message frame ('X' followed by int32 length 4)","Terminate.Decode succeeds on empty payload","Terminate.Decode returns error on non-empty payload","Terminate.MarshalJSON serializes to JSON with Type 'Terminate'"],"goal":"verify github.com/jackc/pgx/v5/pgproto3.Terminate in pkg:golang/github.com/jackc/pgx/v5@v5.10.0","kind":"HOW","packages":["pkg:golang/github.com/jackc/pgx/v5@v5.10.0"],"schemaVersion":1,"symbols":["github.com/jackc/pgx/v5/pgproto3.Terminate"]},"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/jackc/pgx/v5@v5.10.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/jackc/pgx/v5@v5.10.0","symbols":["github.com/jackc/pgx/v5/pgproto3.Terminate"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/jackc/pgx/v5 v5.10.0

github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
github.com/jackc/pgx/v5 v5.10.0 h1:VhSvgU2jSli8o3AqIEOTJr7rZwAEUVo4E4XhR94Zfr0=
github.com/jackc/pgx/v5 v5.10.0/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
golang.org/x/text v0.29.0 h1:1neNs90w9YzJ9BocxfsQNHKuAT4pkghyXc4nhZ6sJvk=
golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

{
  "schemaVersion": 1,
  "goal": "verify github.com/jackc/pgx/v5/pgproto3.Terminate in pkg:golang/github.com/jackc/pgx/v5@v5.10.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/jackc/pgx/v5@v5.10.0"
  ],
  "symbols": [
    "github.com/jackc/pgx/v5/pgproto3.Terminate"
  ]
}

package sample

import (
	"encoding/json"
	"fmt"

	"github.com/jackc/pgx/v5/pgproto3"
)

// EncodeTerminate encodes a Terminate message onto the provided buffer.
func EncodeTerminate(dst []byte) ([]byte, error) {
	var msg pgproto3.Terminate
	return msg.Encode(dst)
}

// DecodeTerminate decodes the payload into a Terminate message.
// The payload should be empty because Terminate has a zero-length message body.
func DecodeTerminate(src []byte) (*pgproto3.Terminate, error) {
	var msg pgproto3.Terminate
	if err := msg.Decode(src); err != nil {
		return nil, fmt.Errorf("decode terminate failed: %w", err)
	}
	return &msg, nil
}

// MarshalTerminateJSON serializes a Terminate message to JSON.
func MarshalTerminateJSON() ([]byte, error) {
	var msg pgproto3.Terminate
	return json.Marshal(msg)
}

// IsFrontendMessage verifies that the message satisfies the pgproto3.FrontendMessage interface.
func IsFrontendMessage(msg pgproto3.FrontendMessage) bool {
	return msg != nil
}

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os"

	"github.com/jackc/pgx/v5/pgproto3"
	"sample"
)

func main() {
	// Assertion 1: pgproto3.Terminate implements pgproto3.FrontendMessage
	var term pgproto3.Terminate
	var frontendMsg pgproto3.FrontendMessage = &term
	if frontendMsg == nil || !sample.IsFrontendMessage(&term) {
		fmt.Fprintf(os.Stderr, "expected Terminate to implement pgproto3.FrontendMessage\n")
		os.Exit(1)
	}

	// Assertion 2: Terminate.Encode appends the 5-byte frontend message frame ('X' followed by int32 length 4)
	encoded, err := sample.EncodeTerminate(nil)
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected Encode to succeed, got error: %v\n", err)
		os.Exit(1)
	}
	expectedFrame := []byte{'X', 0, 0, 0, 4}
	if !bytes.Equal(encoded, expectedFrame) {
		fmt.Fprintf(os.Stderr, "expected encoded frame %v, got %v\n", expectedFrame, encoded)
		os.Exit(1)
	}

	initialBuf := []byte{1, 2, 3}
	encodedWithBuf, err := sample.EncodeTerminate(initialBuf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected Encode with buffer to succeed, got error: %v\n", err)
		os.Exit(1)
	}
	if !bytes.Equal(encodedWithBuf[:3], initialBuf) || !bytes.Equal(encodedWithBuf[3:], expectedFrame) {
		fmt.Fprintf(os.Stderr, "expected buffer append, got %v\n", encodedWithBuf)
		os.Exit(1)
	}

	// Assertion 3: Terminate.Decode succeeds on empty payload
	decoded, err := sample.DecodeTerminate(nil)
	if err != nil || decoded == nil {
		fmt.Fprintf(os.Stderr, "expected Decode(nil) to succeed, got error: %v\n", err)
		os.Exit(1)
	}

	decodedEmpty, err := sample.DecodeTerminate([]byte{})
	if err != nil || decodedEmpty == nil {
		fmt.Fprintf(os.Stderr, "expected Decode([]byte{}) to succeed, got error: %v\n", err)
		os.Exit(1)
	}

	// Assertion 4: Terminate.Decode returns error on non-empty payload
	_, err = sample.DecodeTerminate([]byte{0x01})
	if err == nil {
		fmt.Fprintf(os.Stderr, "expected Decode to fail on non-empty payload, but got nil\n")
		os.Exit(1)
	}

	// Assertion 5: Terminate.MarshalJSON serializes to JSON with Type 'Terminate'
	jsonBytes, err := sample.MarshalTerminateJSON()
	if err != nil {
		fmt.Fprintf(os.Stderr, "expected MarshalJSON to succeed, got error: %v\n", err)
		os.Exit(1)
	}
	var parsed struct {
		Type string `json:"Type"`
	}
	if err := json.Unmarshal(jsonBytes, &parsed); err != nil || parsed.Type != "Terminate" {
		fmt.Fprintf(os.Stderr, "expected JSON with Type 'Terminate', got %s\n", string(jsonBytes))
		os.Exit(1)
	}

	fmt.Println("All pgproto3.Terminate contract assertions passed.")
}