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

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.EscapeVersion 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.EscapeVersion

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:sha256:521970f352adf09ceb18b43cc6720a5d5628dc2f2c391f98de65f4e79e9ee6ff","contract":["module.EscapeVersion returns valid lowercase version strings unchanged","module.EscapeVersion escapes uppercase letters with exclamation mark prefix followed by lowercase letters","module.EscapeVersion handles multiple uppercase letters in prerelease and build metadata","module.EscapeVersion rejects disallowed version strings with InvalidVersionError","module.EscapeVersion output round-trips correctly with module.UnescapeVersion"],"goal":"verify golang.org/x/mod/module.EscapeVersion 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.EscapeVersion"]},"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.EscapeVersion"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

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"
	"log"

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

func main() {
	versions := []string{
		"v1.0.0",
		"v1.2.3-Beta.1",
		"v2.0.0-SNAPSHOT",
	}

	for _, v := range versions {
		escaped, err := module.EscapeVersion(v)
		if err != nil {
			log.Fatalf("failed to escape version %q: %v", v, err)
		}
		fmt.Printf("Original: %s -> Escaped: %s\n", v, escaped)

		unescaped, err := module.UnescapeVersion(escaped)
		if err != nil {
			log.Fatalf("failed to unescape version %q: %v", escaped, err)
		}
		fmt.Printf("Unescaped: %s\n", unescaped)
	}

	// Rejecting disallowed version
	disallowedVer := "v1.0.0/invalid"
	if _, err := module.EscapeVersion(disallowedVer); err != nil {
		fmt.Printf("Successfully rejected disallowed version %q: %v\n", disallowedVer, err)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/mod/module.EscapeVersion 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.EscapeVersion"
  ]
}

package main

import (
	"errors"
	"fmt"
	"os"

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

func main() {
	// Assertion 1: module.EscapeVersion returns valid lowercase version strings unchanged
	{
		validVersions := []string{
			"v1.0.0",
			"v0.1.2",
			"v2.3.4-alpha.1",
			"v1.0.0-beta.2+build.2023",
		}
		for _, v := range validVersions {
			escaped, err := module.EscapeVersion(v)
			if err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion returned error for %q: %v\n", v, err)
				os.Exit(1)
			}
			if escaped != v {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion(%q) = %q, expected %q\n", v, escaped, v)
				os.Exit(1)
			}
		}
	}

	// Assertion 2: module.EscapeVersion escapes uppercase letters with exclamation mark prefix followed by lowercase letters
	{
		testCases := []struct {
			input    string
			expected string
		}{
			{"v1.0.0-Beta", "v1.0.0-!beta"},
			{"v1.0.0-Alpha.1", "v1.0.0-!alpha.1"},
			{"v1.0.0-RC1", "v1.0.0-!r!c1"},
			{"v1.0.0+BUILD", "v1.0.0+!b!u!i!l!d"},
		}
		for _, tc := range testCases {
			escaped, err := module.EscapeVersion(tc.input)
			if err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion returned error for %q: %v\n", tc.input, err)
				os.Exit(1)
			}
			if escaped != tc.expected {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion(%q) = %q, expected %q\n", tc.input, escaped, tc.expected)
				os.Exit(1)
			}
		}
	}

	// Assertion 3: module.EscapeVersion handles multiple uppercase letters in prerelease and build metadata
	{
		testCases := []struct {
			input    string
			expected string
		}{
			{"v2.0.0-SNAPSHOT", "v2.0.0-!s!n!a!p!s!h!o!t"},
			{"v1.0.0-AlphaBetaGamma", "v1.0.0-!alpha!beta!gamma"},
			{"v1.0.0-pre.ALPHA+Metadata.INFO", "v1.0.0-pre.!a!l!p!h!a+!metadata.!i!n!f!o"},
		}
		for _, tc := range testCases {
			escaped, err := module.EscapeVersion(tc.input)
			if err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion returned error for %q: %v\n", tc.input, err)
				os.Exit(1)
			}
			if escaped != tc.expected {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion(%q) = %q, expected %q\n", tc.input, escaped, tc.expected)
				os.Exit(1)
			}
		}
	}

	// Assertion 4: module.EscapeVersion rejects disallowed version strings with InvalidVersionError
	{
		disallowedVersions := []string{
			"",
			"v1.0.0/part",
			"v1.0.0\\part",
			"v1.0.0:part",
			"v1.0.0!bang",
			"v1.0.0*wild",
			"v1.0.0?query",
			"v1.0.0.",
			"...",
			"con",
			"aux",
		}
		for _, inv := range disallowedVersions {
			_, err := module.EscapeVersion(inv)
			if err == nil {
				fmt.Fprintf(os.Stderr, "FAIL: expected error for disallowed version %q, got nil\n", inv)
				os.Exit(1)
			}
			var verErr *module.InvalidVersionError
			if !errors.As(err, &verErr) {
				fmt.Fprintf(os.Stderr, "FAIL: expected InvalidVersionError for %q, got %T (%v)\n", inv, err, err)
				os.Exit(1)
			}
		}
	}

	// Assertion 5: module.EscapeVersion output round-trips correctly with module.UnescapeVersion
	{
		roundTripVersions := []string{
			"v1.0.0",
			"v2.1.0-RC.1",
			"v0.1.2-alpha.Preview+Build.42",
			"v3.0.0-MyPreRelease",
			"v1.2.3-AlphaBetaGamma.4+Meta.DATA",
		}
		for _, v := range roundTripVersions {
			escaped, err := module.EscapeVersion(v)
			if err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: EscapeVersion(%q) failed: %v\n", v, err)
				os.Exit(1)
			}
			unescaped, err := module.UnescapeVersion(escaped)
			if err != nil {
				fmt.Fprintf(os.Stderr, "FAIL: UnescapeVersion(%q) failed: %v\n", escaped, err)
				os.Exit(1)
			}
			if unescaped != v {
				fmt.Fprintf(os.Stderr, "FAIL: round-trip mismatch for %q: got %q\n", v, unescaped)
				os.Exit(1)
			}
		}
	}

	fmt.Println("PASS: all EscapeVersion contract assertions passed")
}