golang.org/x/term v0.0.0-20201117132131-f5c789dd3221: NewTerminal

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 golang.org/x/term.NewTerminal in pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221
Demonstrate these symbols/APIs:
  - golang.org/x/term.NewTerminal

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:sha256:4df5687e6c447157f02542f4229d97f6dc6cf74bd1811912ba82ef4d06ffa7f9","contract":["term.NewTerminal initializes a VT100 terminal instance wrapping an io.ReadWriter with an initial prompt","term.Terminal.ReadLine reads CRLF-terminated lines from the underlying reader and writes the active prompt","term.Terminal.SetPrompt updates the prompt string emitted before subsequent ReadLine calls","term.Terminal.ReadPassword reads a line of input with a custom prompt without echoing the password bytes","term.Terminal.Write writes output to the underlying writer while translating LF to CRLF","term.Terminal.SetSize updates the terminal width and height dimensions without error"],"goal":"verify golang.org/x/term.NewTerminal in pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221","kind":"HOW","packages":["pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221"],"schemaVersion":1,"symbols":["golang.org/x/term.NewTerminal"]},"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/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221","symbols":["golang.org/x/term.NewTerminal"],"verifierAdapter":"golang@1"}

module sample

go 1.21

require golang.org/x/term v0.0.0-20201117132131-f5c789dd3221

require golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 // indirect

golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/term v0.0.0-20201117132131-f5c789dd3221 h1:/ZHdbVpdR/jk3g30/d4yUL0JU9kksj8+F/bnQUVLGDM=
golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/term.NewTerminal in pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/term@v0.0.0-20201117132131-f5c789dd3221"
  ],
  "symbols": [
    "golang.org/x/term.NewTerminal"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"
	"strings"

	"golang.org/x/term"
)

type duplexBuffer struct {
	rx *bytes.Buffer
	tx *bytes.Buffer
}

func (d *duplexBuffer) Read(p []byte) (int, error) {
	return d.rx.Read(p)
}

func (d *duplexBuffer) Write(p []byte) (int, error) {
	return d.tx.Write(p)
}

func fail(msg string, args ...any) {
	fmt.Fprintf(os.Stderr, msg+"\n", args...)
	os.Exit(1)
}

func main() {
	// 1. Initialize terminal with prompt and read a line
	buf := &duplexBuffer{
		rx: bytes.NewBufferString("echo test\r\nsecond line\r\nsecret123\r\n"),
		tx: &bytes.Buffer{},
	}
	t := term.NewTerminal(buf, "prompt> ")
	if t == nil {
		fail("expected non-nil *term.Terminal from NewTerminal")
	}

	line1, err := t.ReadLine()
	if err != nil {
		fail("ReadLine failed: %v", err)
	}
	if line1 != "echo test" {
		fail("expected 'echo test', got %q", line1)
	}
	if !strings.Contains(buf.tx.String(), "prompt> ") {
		fail("expected output to include initial prompt 'prompt> ', got %q", buf.tx.String())
	}

	// 2. Update prompt and read next line
	t.SetPrompt("next> ")
	line2, err := t.ReadLine()
	if err != nil {
		fail("second ReadLine failed: %v", err)
	}
	if line2 != "second line" {
		fail("expected 'second line', got %q", line2)
	}
	if !strings.Contains(buf.tx.String(), "next> ") {
		fail("expected output to include updated prompt 'next> ', got %q", buf.tx.String())
	}

	// 3. Read password without echoing characters
	buf.tx.Reset()
	pw, err := t.ReadPassword("Password: ")
	if err != nil {
		fail("ReadPassword failed: %v", err)
	}
	if pw != "secret123" {
		fail("expected password 'secret123', got %q", pw)
	}
	if !strings.Contains(buf.tx.String(), "Password: ") {
		fail("expected password prompt in output, got %q", buf.tx.String())
	}
	if strings.Contains(buf.tx.String(), "secret123") {
		fail("expected password not to be echoed in output, got %q", buf.tx.String())
	}

	// 4. Write output through terminal and verify LF -> CRLF conversion
	buf.tx.Reset()
	n, err := t.Write([]byte("alpha\nbeta\n"))
	if err != nil {
		fail("Write failed: %v", err)
	}
	if n != 11 {
		fail("expected 11 bytes written, got %d", n)
	}
	if buf.tx.String() != "alpha\r\nbeta\r\n" {
		fail("expected CRLF translated output 'alpha\\r\\nbeta\\r\\n', got %q", buf.tx.String())
	}

	// 4. Resize terminal and verify Escape sequence structure exists
	if err := t.SetSize(100, 30); err != nil {
		fail("SetSize failed: %v", err)
	}
	if len(t.Escape.Reset) == 0 {
		fail("expected non-empty Escape.Reset sequence on initialized Terminal")
	}
}