github.com/kr/pty v1.1.8: pty

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 pty in pkg:golang/github.com/kr/pty@v1.1.8
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/kr/pty@v1.1.8
Demonstrate these symbols/APIs:
  - pty

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:sha256:934ec249eb61c1b4087a0381f5533535861bf452645516259d56087276ebda94","contract":["pty.Open returns non-nil pty master and pts slave terminal files","pty.Setsize and pty.Getsize configure and report terminal window rows and columns","pty.GetsizeFull returns Winsize matching configured rows and columns","pty.InheritSize propagates window dimensions from pty master to slave","data written to slave terminal is received on pty master"],"goal":"verify pty in pkg:golang/github.com/kr/pty@v1.1.8","kind":"HOW","packages":["pkg:golang/github.com/kr/pty@v1.1.8"],"schemaVersion":1,"symbols":["pty"]},"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/kr/pty@v1.1.8"],"schemaVersion":1,"subject":"pkg:golang/github.com/kr/pty@v1.1.8","symbols":["pty"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/kr/pty v1.1.8

require (
	github.com/creack/pty v1.1.7 // indirect
	golang.org/x/sys v0.48.0 // indirect
)

github.com/creack/pty v1.1.7 h1:6pwm8kMQKCmgUg0ZHTm5+/YvRK0s3THD/28+T6/kk4A=
github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
github.com/kr/pty v1.1.8 h1:AkaSdXYQOWeaO3neb8EM634ahkXXe3jYbVh/F9lq+GI=
github.com/kr/pty v1.1.8/go.mod h1:O1sed60cT9XZ5uDucP5qwvh+TE3NnUj51EiZO/lmSfw=
golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=

package main

import (
	"fmt"
	"os"

	"github.com/kr/pty"
)

func main() {
	ptmx, pts, err := pty.Open()
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to open pty: %v\n", err)
		os.Exit(1)
	}
	defer ptmx.Close()
	defer pts.Close()

	size := &pty.Winsize{Rows: 24, Cols: 80}
	if err := pty.Setsize(ptmx, size); err != nil {
		fmt.Fprintf(os.Stderr, "failed to set size: %v\n", err)
		os.Exit(1)
	}

	rows, cols, err := pty.Getsize(ptmx)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to get size: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("pty window size: rows=%d, cols=%d\n", rows, cols)

	message := []byte("hello from pty\n")
	if _, err := pts.Write(message); err != nil {
		fmt.Fprintf(os.Stderr, "failed to write to slave: %v\n", err)
		os.Exit(1)
	}

	buf := make([]byte, 64)
	n, err := ptmx.Read(buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to read from master: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("received on master: %s", string(buf[:n]))
}

{
  "schemaVersion": 1,
  "goal": "verify pty in pkg:golang/github.com/kr/pty@v1.1.8",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/kr/pty@v1.1.8"
  ],
  "symbols": [
    "pty"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"

	"github.com/kr/pty"
)

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

func runContractTests() error {
	// 1. pty.Open returns non-nil pty master and pts slave terminal files
	ptmx, pts, err := pty.Open()
	if err != nil {
		return fmt.Errorf("pty.Open failed: %w", err)
	}
	defer ptmx.Close()
	defer pts.Close()

	if ptmx == nil || pts == nil {
		return fmt.Errorf("pty.Open returned nil file descriptor")
	}
	if ptmx.Fd() == 0 || pts.Fd() == 0 {
		return fmt.Errorf("invalid file descriptor returned")
	}

	// 2. pty.Setsize and pty.Getsize configure and report terminal window rows and columns
	initialSize := &pty.Winsize{Rows: 30, Cols: 100, X: 0, Y: 0}
	if err := pty.Setsize(ptmx, initialSize); err != nil {
		return fmt.Errorf("pty.Setsize failed: %w", err)
	}
	rows, cols, err := pty.Getsize(ptmx)
	if err != nil {
		return fmt.Errorf("pty.Getsize failed: %w", err)
	}
	if rows != 30 || cols != 100 {
		return fmt.Errorf("expected rows=30, cols=100; got rows=%d, cols=%d", rows, cols)
	}

	// 3. pty.GetsizeFull returns Winsize matching configured rows and columns
	fullSize, err := pty.GetsizeFull(ptmx)
	if err != nil {
		return fmt.Errorf("pty.GetsizeFull failed: %w", err)
	}
	if fullSize.Rows != 30 || fullSize.Cols != 100 {
		return fmt.Errorf("expected fullSize rows=30, cols=100; got rows=%d, cols=%d", fullSize.Rows, fullSize.Cols)
	}

	// 4. pty.InheritSize propagates window dimensions from pty master to slave
	newSize := &pty.Winsize{Rows: 48, Cols: 132, X: 1280, Y: 800}
	if err := pty.Setsize(ptmx, newSize); err != nil {
		return fmt.Errorf("pty.Setsize newSize failed: %w", err)
	}
	if err := pty.InheritSize(ptmx, pts); err != nil {
		return fmt.Errorf("pty.InheritSize failed: %w", err)
	}
	slaveRows, slaveCols, err := pty.Getsize(pts)
	if err != nil {
		return fmt.Errorf("pty.Getsize(pts) failed: %w", err)
	}
	if slaveRows != 48 || slaveCols != 132 {
		return fmt.Errorf("expected slave rows=48, cols=132; got rows=%d, cols=%d", slaveRows, slaveCols)
	}

	// 5. data written to slave terminal is received on pty master
	payload := []byte("CodeSampleX verification payload\n")
	if _, err := pts.Write(payload); err != nil {
		return fmt.Errorf("pts.Write failed: %w", err)
	}

	buf := make([]byte, 128)
	n, err := ptmx.Read(buf)
	if err != nil {
		return fmt.Errorf("ptmx.Read failed: %w", err)
	}
	if !bytes.Contains(buf[:n], []byte("CodeSampleX verification payload")) {
		return fmt.Errorf("expected ptmx buffer to contain payload, got: %q", string(buf[:n]))
	}

	return nil
}