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

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.InvalidVersionError 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.InvalidVersionError

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:sha256:119dd6e526149a3bcccc80e896528b0ddd040b77f02e109e3b431a4353b71b94","contract":["module.CheckPathMajor returns *InvalidVersionError when version does not match path major","module.EscapeVersion returns *InvalidVersionError for disallowed version string","module.Check returns *ModuleError wrapping *InvalidVersionError for non-semantic version","module.InvalidVersionError Error() formats message with noun, version and underlying error","module.InvalidVersionError Unwrap() returns the underlying wrapped error"],"goal":"verify golang.org/x/mod/module.InvalidVersionError 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.InvalidVersionError"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","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/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.InvalidVersionError"],"verifierAdapter":"golang@1"}

module example.com/sample

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 (
	"errors"
	"fmt"

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

func main() {
	err := module.Check("example.com/mod", "invalid-semver")
	if err != nil {
		var ive *module.InvalidVersionError
		if errors.As(err, &ive) {
			fmt.Printf("Invalid version detected: %s (pseudo: %t): %v\n", ive.Version, ive.Pseudo, ive.Err)
			fmt.Printf("Formatted error: %s\n", ive.Error())
			return
		}
		fmt.Printf("Unexpected error: %v\n", err)
		return
	}
	fmt.Println("Version is valid.")
}

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

package main

import (
	"errors"
	"fmt"
	"os"

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

func main() {
	// 1. module.CheckPathMajor returns *InvalidVersionError when version does not match path major
	{
		err := module.CheckPathMajor("v2.0.0", "")
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected error for mismatched path major\n")
			os.Exit(1)
		}
		var ive *module.InvalidVersionError
		if !errors.As(err, &ive) {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected *module.InvalidVersionError, got %T\n", err)
			os.Exit(1)
		}
		if ive.Version != "v2.0.0" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected Version 'v2.0.0', got %q\n", ive.Version)
			os.Exit(1)
		}
		if ive.Err == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected non-nil Err\n")
			os.Exit(1)
		}
	}

	// 2. module.EscapeVersion returns *InvalidVersionError for disallowed version string
	{
		_, err := module.EscapeVersion("v1.0.0!bad")
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected error for disallowed version string\n")
			os.Exit(1)
		}
		var ive *module.InvalidVersionError
		if !errors.As(err, &ive) {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected *module.InvalidVersionError, got %T\n", err)
			os.Exit(1)
		}
		if ive.Version != "v1.0.0!bad" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected Version 'v1.0.0!bad', got %q\n", ive.Version)
			os.Exit(1)
		}
		if ive.Err == nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected non-nil Err\n")
			os.Exit(1)
		}
	}

	// 3. module.Check returns *ModuleError wrapping *InvalidVersionError for non-semantic version
	{
		err := module.Check("example.com/mod", "invalid-semver")
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected error for invalid semver\n")
			os.Exit(1)
		}
		var mErr *module.ModuleError
		if !errors.As(err, &mErr) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected *module.ModuleError, got %T\n", err)
			os.Exit(1)
		}
		var ive *module.InvalidVersionError
		if !errors.As(err, &ive) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected wrapped *module.InvalidVersionError, got %T\n", err)
			os.Exit(1)
		}
		if ive.Version != "invalid-semver" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected Version 'invalid-semver', got %q\n", ive.Version)
			os.Exit(1)
		}
	}

	// 4. module.InvalidVersionError Error() formats message with noun, version and underlying error
	{
		iveStandard := &module.InvalidVersionError{
			Version: "v1.0",
			Pseudo:  false,
			Err:     errors.New("not canonical"),
		}
		msgStandard := iveStandard.Error()
		expectedStandard := "version \"v1.0\" invalid: not canonical"
		if msgStandard != expectedStandard {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected %q, got %q\n", expectedStandard, msgStandard)
			os.Exit(1)
		}

		ivePseudo := &module.InvalidVersionError{
			Version: "v0.0.0-bad",
			Pseudo:  true,
			Err:     errors.New("malformed time"),
		}
		msgPseudo := ivePseudo.Error()
		expectedPseudo := "pseudo-version \"v0.0.0-bad\" invalid: malformed time"
		if msgPseudo != expectedPseudo {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected %q, got %q\n", expectedPseudo, msgPseudo)
			os.Exit(1)
		}
	}

	// 5. module.InvalidVersionError Unwrap() returns the underlying wrapped error
	{
		underlying := errors.New("underlying cause")
		ive := &module.InvalidVersionError{
			Version: "v1.0.0",
			Err:     underlying,
		}
		if ive.Unwrap() != underlying {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: Unwrap() did not return underlying error\n")
			os.Exit(1)
		}
		if !errors.Is(ive, underlying) {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: errors.Is did not match underlying error\n")
			os.Exit(1)
		}
	}

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