github.com/chzyer/readline v1.5.1: NewEx

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/chzyer/readline.NewEx in pkg:golang/github.com/chzyer/readline@v1.5.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/chzyer/readline@v1.5.1
Demonstrate these symbols/APIs:
  - github.com/chzyer/readline.NewEx

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:sha256:6141b1523971cc4fcb4ae0e32f7205e17c1b945aae27e1ef4108dfd98b49aedd","contract":["readline.NewEx creates a valid Instance from a custom Config with specified Prompt and streams","readline.NewEx reads sequential lines from configured custom Stdin","readline.NewEx returns io.EOF on Readline when configured Stdin is exhausted","readline.NewEx instance allows dynamic prompt updates via SetPrompt","readline.NewEx accepts AutoComplete prefix completer in Config","readline.NewEx instance generates masked password config via GenPasswordConfig","readline.NewEx instance Close method cleanly releases terminal resources"],"goal":"verify github.com/chzyer/readline.NewEx in pkg:golang/github.com/chzyer/readline@v1.5.1","kind":"HOW","packages":["pkg:golang/github.com/chzyer/readline@v1.5.1"],"schemaVersion":1,"symbols":["github.com/chzyer/readline.NewEx"]},"contractCommand":["go","run","./test"],"environment":{"arch":"amd64","compiler":"go","compilerVersion":"1.26.6","distro":"ubuntu","ecosystem":"golang","language":"go","languageVersion":"1.26.6","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/chzyer/readline@v1.5.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/chzyer/readline@v1.5.1","symbols":["github.com/chzyer/readline.NewEx"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/chzyer/readline v1.5.1

require golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 // indirect

github.com/chzyer/logex v1.2.1 h1:XHDu3E6q+gdHgsdTPH6ImJMIp436vR6MPtH8gP05QzM=
github.com/chzyer/logex v1.2.1/go.mod h1:JLbx6lG2kDbNRFnfkgvh4eRJRPX1QCoOIWomwysCBrQ=
github.com/chzyer/readline v1.5.1 h1:upd/6fQk4src78LMRzh5vItIt361/o4uq553V8B5sGI=
github.com/chzyer/readline v1.5.1/go.mod h1:Eh+b79XXUwfKfcPLepksvw2tcLE/Ct21YObkaSkeBlk=
github.com/chzyer/test v1.0.0 h1:p3BQDXSxOhOG0P9z6/hGnII4LGiEPOYBhs8asl/fC04=
github.com/chzyer/test v1.0.0/go.mod h1:2JlltgoNkt4TW/z9V/IzDdFaMTM2JPIi26O1pF38GC8=
golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 h1:y/woIyUBFbpQGKS0u1aHF/40WUDnek3fPOyD08H5Vng=
golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

package main

import (
	"bytes"
	"fmt"
	"io"
	"strings"

	"github.com/chzyer/readline"
)

func main() {
	// Demonstrates configuring and using readline.NewEx with custom parameters
	completer := readline.NewPrefixCompleter(
		readline.PcItem("help"),
		readline.PcItem("version"),
		readline.PcItem("exit"),
	)

	// In an interactive shell os.Stdin and os.Stdout are typically used,
	// but NewEx allows supplying custom io.ReadCloser and io.Writer streams.
	input := strings.NewReader("help\nversion\nexit\n")
	output := &bytes.Buffer{}

	cfg := &readline.Config{
		Prompt:                 "demo> ",
		Stdin:                  io.NopCloser(input),
		Stdout:                 output,
		AutoComplete:           completer,
		HistoryLimit:           100,
		DisableAutoSaveHistory: true,
	}

	rl, err := readline.NewEx(cfg)
	if err != nil {
		fmt.Printf("failed to initialize readline instance: %v\n", err)
		return
	}
	defer rl.Close()

	for {
		line, err := rl.Readline()
		if err != nil {
			if err == io.EOF {
				break
			}
			fmt.Printf("read error: %v\n", err)
			break
		}
		fmt.Printf("received line: %s\n", line)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/chzyer/readline.NewEx in pkg:golang/github.com/chzyer/readline@v1.5.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/chzyer/readline@v1.5.1"
  ],
  "symbols": [
    "github.com/chzyer/readline.NewEx"
  ]
}

package main

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

	"github.com/chzyer/readline"
)

func main() {
	// Contract 1: readline.NewEx creates a valid Instance from a custom Config with specified Prompt and streams
	{
		in := io.NopCloser(strings.NewReader("ping\npong\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "prompt> ",
			Stdin:                  in,
			Stdout:                 out,
			HistoryLimit:           50,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 1 failed: readline.NewEx returned error: %v\n", err)
			os.Exit(1)
		}
		if rl == nil {
			fmt.Fprintln(os.Stderr, "Contract 1 failed: readline.NewEx returned nil instance")
			os.Exit(1)
		}
		if rl.Config == nil || rl.Config.Prompt != "prompt> " {
			fmt.Fprintf(os.Stderr, "Contract 1 failed: rl.Config.Prompt got %q, want %q\n", rl.Config.Prompt, "prompt> ")
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 2: readline.NewEx reads sequential lines from configured custom Stdin
	{
		in := io.NopCloser(strings.NewReader("first line\nsecond line\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "> ",
			Stdin:                  in,
			Stdout:                 out,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 2 failed: NewEx error: %v\n", err)
			os.Exit(1)
		}

		line1, err := rl.Readline()
		if err != nil || line1 != "first line" {
			fmt.Fprintf(os.Stderr, "Contract 2 failed: line 1 got %q (err: %v), want %q\n", line1, err, "first line")
			_ = rl.Close()
			os.Exit(1)
		}

		line2, err := rl.Readline()
		if err != nil || line2 != "second line" {
			fmt.Fprintf(os.Stderr, "Contract 2 failed: line 2 got %q (err: %v), want %q\n", line2, err, "second line")
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 3: readline.NewEx returns io.EOF on Readline when configured Stdin is exhausted
	{
		in := io.NopCloser(strings.NewReader("only-one\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "> ",
			Stdin:                  in,
			Stdout:                 out,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 3 failed: NewEx error: %v\n", err)
			os.Exit(1)
		}

		_, err = rl.Readline()
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 3 failed: first read error: %v\n", err)
			_ = rl.Close()
			os.Exit(1)
		}

		_, err = rl.Readline()
		if err != io.EOF {
			fmt.Fprintf(os.Stderr, "Contract 3 failed: expected io.EOF, got: %v\n", err)
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 4: readline.NewEx instance allows dynamic prompt updates via SetPrompt
	{
		in := io.NopCloser(strings.NewReader("sample\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "initial> ",
			Stdin:                  in,
			Stdout:                 out,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 4 failed: NewEx error: %v\n", err)
			os.Exit(1)
		}

		rl.SetPrompt("updated> ")
		line, err := rl.Readline()
		if err != nil || line != "sample" {
			fmt.Fprintf(os.Stderr, "Contract 4 failed: Readline after SetPrompt failed: %v\n", err)
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 5: readline.NewEx accepts AutoComplete prefix completer in Config
	{
		completer := readline.NewPrefixCompleter(
			readline.PcItem("get"),
			readline.PcItem("set"),
		)
		in := io.NopCloser(strings.NewReader("get\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "> ",
			Stdin:                  in,
			Stdout:                 out,
			AutoComplete:           completer,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 5 failed: NewEx with AutoComplete failed: %v\n", err)
			os.Exit(1)
		}

		if rl.Config.AutoComplete == nil {
			fmt.Fprintln(os.Stderr, "Contract 5 failed: AutoComplete is nil in rl.Config")
			_ = rl.Close()
			os.Exit(1)
		}

		line, err := rl.Readline()
		if err != nil || line != "get" {
			fmt.Fprintf(os.Stderr, "Contract 5 failed: Readline got %q, want 'get'\n", line)
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 6: readline.NewEx instance generates masked password config via GenPasswordConfig
	{
		in := io.NopCloser(strings.NewReader("data\n"))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "pass> ",
			Stdin:                  in,
			Stdout:                 out,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 6 failed: NewEx error: %v\n", err)
			os.Exit(1)
		}

		pwdCfg := rl.GenPasswordConfig()
		if pwdCfg == nil {
			fmt.Fprintln(os.Stderr, "Contract 6 failed: GenPasswordConfig returned nil")
			_ = rl.Close()
			os.Exit(1)
		}
		if !pwdCfg.EnableMask {
			fmt.Fprintln(os.Stderr, "Contract 6 failed: EnableMask should be true in GenPasswordConfig")
			_ = rl.Close()
			os.Exit(1)
		}
		_ = rl.Close()
	}

	// Contract 7: readline.NewEx instance Close method cleanly releases terminal resources
	{
		in := io.NopCloser(strings.NewReader(""))
		out := &bytes.Buffer{}
		cfg := &readline.Config{
			Prompt:                 "> ",
			Stdin:                  in,
			Stdout:                 out,
			DisableAutoSaveHistory: true,
		}

		rl, err := readline.NewEx(cfg)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Contract 7 failed: NewEx error: %v\n", err)
			os.Exit(1)
		}

		if err := rl.Close(); err != nil {
			fmt.Fprintf(os.Stderr, "Contract 7 failed: rl.Close returned error: %v\n", err)
			os.Exit(1)
		}
	}

	fmt.Println("All contract assertions passed successfully.")
}