gopkg.in/errgo.v2 v2.1.0: errors.Details

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 gopkg.in/errgo.v2/errors.Details in pkg:golang/gopkg.in/errgo.v2@v2.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/gopkg.in/errgo.v2@v2.1.0
Demonstrate these symbols/APIs:
  - gopkg.in/errgo.v2/errors.Details

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:ad8b7454d0c381bc2adb13cd6e14f7acd5d23e17b988b723faeb5034ec8f585f","contract":["errors.Details returns \"[]\" for nil error","errors.Details formats an unwrapped error with enclosing brackets","errors.Details includes error message and caller file location for errors.New","errors.Details formats wrapped errors with multiple stack trace frames","errors.Details includes annotation context added by errors.Note","errors.Details formats standard library errors without caller file location","sample.Details returns identical output to errors.Details"],"goal":"verify gopkg.in/errgo.v2/errors.Details in pkg:golang/gopkg.in/errgo.v2@v2.1.0","kind":"HOW","packages":["pkg:golang/gopkg.in/errgo.v2@v2.1.0"],"schemaVersion":1,"symbols":["gopkg.in/errgo.v2/errors.Details"]},"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/gopkg.in/errgo.v2@v2.1.0"],"schemaVersion":1,"subject":"pkg:golang/gopkg.in/errgo.v2@v2.1.0","symbols":["gopkg.in/errgo.v2/errors.Details"],"verifierAdapter":"golang@1"}

package sample

import (
	"gopkg.in/errgo.v2/errors"
)

// Details returns the error details string for the given error.
func Details(err error) string {
	return errors.Details(err)
}

// New creates a new error with no cause.
func New(msg string) error {
	return errors.New(msg)
}

// Wrap wraps an error with caller location information.
func Wrap(err error) error {
	return errors.Wrap(err)
}

// Note wraps an error with an additional message prefix and cause filter.
func Note(err error, shouldPreserveCause func(error) bool, msg string) error {
	return errors.Note(err, shouldPreserveCause, msg)
}

module sample

go 1.26.6

require gopkg.in/errgo.v2 v2.1.0

github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/errgo.v2 v2.1.0 h1:0vLT13EuvQ0hNvakwLuFZ/jYrLp5F3kcWHXdRggjCE8=
gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=

{
  "schemaVersion": 1,
  "goal": "verify gopkg.in/errgo.v2/errors.Details in pkg:golang/gopkg.in/errgo.v2@v2.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/gopkg.in/errgo.v2@v2.1.0"
  ],
  "symbols": [
    "gopkg.in/errgo.v2/errors.Details"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

	"gopkg.in/errgo.v2/errors"
	"sample"
)

func main() {
	// Assertion 1: errors.Details returns "[]" for nil error
	if got := errors.Details(nil); got != "[]" {
		fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected %q, got %q\n", "[]", got)
		os.Exit(1)
	}

	// Assertion 2: errors.Details formats an unwrapped error with enclosing brackets
	baseErr := errors.New("base failure")
	baseDetails := errors.Details(baseErr)
	if !strings.HasPrefix(baseDetails, "[\n") || !strings.HasSuffix(baseDetails, "\n]") {
		fmt.Fprintf(os.Stderr, "Assertion 2 failed: expected brackets, got %q\n", baseDetails)
		os.Exit(1)
	}

	// Assertion 3: errors.Details includes error message and caller file location for errors.New
	if !strings.Contains(baseDetails, "base failure") || !strings.Contains(baseDetails, "contract.go:") {
		fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected message and location, got %q\n", baseDetails)
		os.Exit(1)
	}

	// Assertion 4: errors.Details formats wrapped errors with multiple stack trace frames
	wrapped := errors.Wrap(baseErr)
	wrappedDetails := errors.Details(wrapped)
	if strings.Count(wrappedDetails, "\t{") != 2 || !strings.Contains(wrappedDetails, "base failure") {
		fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected 2 frames, got %q\n", wrappedDetails)
		os.Exit(1)
	}

	// Assertion 5: errors.Details includes annotation context added by errors.Note
	noted := errors.Note(baseErr, errors.Any, "operation timed out")
	notedDetails := errors.Details(noted)
	if !strings.Contains(notedDetails, "operation timed out") || !strings.Contains(notedDetails, "base failure") {
		fmt.Fprintf(os.Stderr, "Assertion 5 failed: expected note and cause, got %q\n", notedDetails)
		os.Exit(1)
	}

	// Assertion 6: errors.Details formats standard library errors without caller file location
	stdErr := fmt.Errorf("simple standard error")
	expectedStd := "[\n\t{simple standard error}\n]"
	if got := errors.Details(stdErr); got != expectedStd {
		fmt.Fprintf(os.Stderr, "Assertion 6 failed: expected %q, got %q\n", expectedStd, got)
		os.Exit(1)
	}

	// Assertion 7: sample.Details returns identical output to errors.Details
	if got := sample.Details(wrapped); got != wrappedDetails {
		fmt.Fprintf(os.Stderr, "Assertion 7 failed: sample.Details != errors.Details\n")
		os.Exit(1)
	}
}