golang.org/x/mod v0.39.0: module.CheckPath

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/mod/module.CheckPath in pkg:golang/golang.org/x/mod@v0.39.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/mod@v0.39.0
Demonstrate these symbols/APIs:
  - golang.org/x/mod/module.CheckPath

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:f507519dbdbc518b20d64398b6e4d73c1e9f44c8b3a36a3cf83b71b13d681f3f","contract":["module.CheckPath accepts valid module paths and rejects paths with invalid characters or leading slashes"],"goal":"verify golang.org/x/mod/module.CheckPath in pkg:golang/golang.org/x/mod@v0.39.0","kind":"HOW","packages":["pkg:golang/golang.org/x/mod@v0.39.0"],"schemaVersion":1,"symbols":["golang.org/x/mod/module.CheckPath"]},"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/mod@v0.39.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/mod@v0.39.0","symbols":["golang.org/x/mod/module.CheckPath"],"verifierAdapter":"golang@1"}

module sample-checkpath

go 1.25.0

require golang.org/x/mod v0.39.0

golang.org/x/mod v0.39.0 h1:UF5zwQdCRRUpHfyPwr7d4UrGiVeldIsogtzWVnczL74=
golang.org/x/mod v0.39.0/go.mod h1:bvIbwjQ0HUFFf5AKukeeYQG4ZBUG9yxQbR9aEweIwYY=

package main

import (
	"fmt"

	"golang.org/x/mod/module"
)

func main() {
	path := "example.com/user/repo"
	if err := module.CheckPath(path); err != nil {
		fmt.Printf("invalid module path: %v\n", err)
		return
	}
	fmt.Printf("valid module path: %s\n", path)

	invalidPath := "/leading/slash"
	if err := module.CheckPath(invalidPath); err != nil {
		fmt.Printf("rejected invalid path %q: %v\n", invalidPath, err)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/mod/module.CheckPath in pkg:golang/golang.org/x/mod@v0.39.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/mod@v0.39.0"
  ],
  "symbols": [
    "golang.org/x/mod/module.CheckPath"
  ]
}

package main

import (
	"fmt"
	"os"

	"golang.org/x/mod/module"
)

func main() {
	// Assertion 1: module.CheckPath accepts valid module paths and rejects paths with invalid characters or leading slashes
	{
		validPaths := []string{
			"example.com/pkg",
			"golang.org/x/mod",
			"github.com/user/project",
		}
		for _, p := range validPaths {
			if err := module.CheckPath(p); err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: CheckPath rejected valid path %q: %v\n", p, err)
				os.Exit(1)
			}
		}

		invalidPaths := []string{
			"/leading/slash",
			"trailing/slash/",
			"",
			"-invalid/start",
		}
		for _, p := range invalidPaths {
			if err := module.CheckPath(p); err == nil {
				fmt.Fprintf(os.Stderr, "FAIL: CheckPath accepted invalid path %q\n", p)
				os.Exit(1)
			}
		}
	}

	fmt.Println("PASS: module.CheckPath contract passed")
}