github.com/go-sql-driver/mysql v1.7.1: MySQLError

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/go-sql-driver/mysql.MySQLError in pkg:golang/github.com/go-sql-driver/mysql@v1.7.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/go-sql-driver/mysql@v1.7.1
Demonstrate these symbols/APIs:
  - github.com/go-sql-driver/mysql.MySQLError
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:fd60c0ecc4d7f9d21abf6c50f4e5379ab804f65743edd182e45cb95fd4405fa1","contract":["mysql.MySQLError struct stores Number, SQLState, and Message fields","mysql.MySQLError.Error returns formatted error string with error number, SQLState, and message","mysql.MySQLError.Is matches target error when target has matching error Number","mysql.MySQLError.Is returns false when target has different error Number","errors.As successfully unwraps *mysql.MySQLError from wrapped error chain","errors.Is correctly matches target *mysql.MySQLError through wrapped error chain"],"goal":"verify github.com/go-sql-driver/mysql.MySQLError in pkg:golang/github.com/go-sql-driver/mysql@v1.7.1","kind":"HOW","packages":["pkg:golang/github.com/go-sql-driver/mysql@v1.7.1"],"schemaVersion":1,"symbols":["github.com/go-sql-driver/mysql.MySQLError"]},"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/github.com/go-sql-driver/mysql@v1.7.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/go-sql-driver/mysql@v1.7.1","symbols":["github.com/go-sql-driver/mysql.MySQLError"],"verifierAdapter":"golang@1"}

module sample-mysql-error

go 1.26.6

require github.com/go-sql-driver/mysql v1.7.1

github.com/go-sql-driver/mysql v1.7.1 h1:lUIinVbN1DY0xBg0eMOzmmtGoHwWBbvnWubQUrtU8EI=
github.com/go-sql-driver/mysql v1.7.1/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=

package main

import (
	"errors"
	"fmt"

	"github.com/go-sql-driver/mysql"
)

func main() {
	// Construct a MySQLError representing a MySQL server error
	originalErr := &mysql.MySQLError{
		Number:   1062,
		SQLState: [5]byte{'2', '3', '0', '0', '0'},
		Message:  "Duplicate entry 'user@example.com' for key 'users.email_unique'",
	}

	// Format error message using Error() method
	fmt.Printf("MySQL Error String: %s\n", originalErr.Error())
	fmt.Printf("Error Number: %d\n", originalErr.Number)
	fmt.Printf("SQLState: %s\n", string(originalErr.SQLState[:]))
	fmt.Printf("Message: %s\n", originalErr.Message)

	// Wrap the MySQL error
	wrappedErr := fmt.Errorf("database query failed: %w", originalErr)

	// Use errors.As to unwrap and inspect the MySQLError
	var targetMySQLErr *mysql.MySQLError
	if errors.As(wrappedErr, &targetMySQLErr) {
		fmt.Printf("Unwrapped MySQL Error Number: %d\n", targetMySQLErr.Number)
	}

	// Use errors.Is to match specific MySQL error numbers
	duplicateEntryErr := &mysql.MySQLError{Number: 1062}
	if errors.Is(wrappedErr, duplicateEntryErr) {
		fmt.Println("Matched duplicate entry error (1062) via errors.Is")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/go-sql-driver/mysql.MySQLError in pkg:golang/github.com/go-sql-driver/mysql@v1.7.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/go-sql-driver/mysql@v1.7.1"
  ],
  "symbols": [
    "github.com/go-sql-driver/mysql.MySQLError"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"errors"
	"fmt"
	"os"

	"github.com/go-sql-driver/mysql"
)

func main() {
	// Assertion 1: mysql.MySQLError struct stores Number, SQLState, and Message fields
	{
		errVal := &mysql.MySQLError{
			Number:   1045,
			SQLState: [5]byte{'2', '8', '0', '0', '0'},
			Message:  "Access denied for user",
		}
		if errVal.Number != 1045 {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected Number 1045, got %d\n", errVal.Number)
			os.Exit(1)
		}
		if string(errVal.SQLState[:]) != "28000" {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected SQLState 28000, got %s\n", string(errVal.SQLState[:]))
			os.Exit(1)
		}
		if errVal.Message != "Access denied for user" {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected Message %q, got %q\n", "Access denied for user", errVal.Message)
			os.Exit(1)
		}
	}

	// Assertion 2: mysql.MySQLError.Error returns formatted error string with error number, SQLState, and message
	{
		errVal := &mysql.MySQLError{
			Number:   1062,
			SQLState: [5]byte{'2', '3', '0', '0', '0'},
			Message:  "Duplicate entry 'test' for key 'PRIMARY'",
		}
		expected := "Error 1062 (23000): Duplicate entry 'test' for key 'PRIMARY'"
		if got := errVal.Error(); got != expected {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

	// Assertion 3: mysql.MySQLError.Is matches target error when target has matching error Number
	{
		errVal := &mysql.MySQLError{
			Number:   1146,
			SQLState: [5]byte{'4', '2', 'S', '0', '2'},
			Message:  "Table 'testdb.nonexistent' doesn't exist",
		}
		target := &mysql.MySQLError{
			Number: 1146,
		}
		if !errors.Is(errVal, target) {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected errors.Is to return true for matching Number 1146\n")
			os.Exit(1)
		}
	}

	// Assertion 4: mysql.MySQLError.Is returns false when target has different error Number
	{
		errVal := &mysql.MySQLError{
			Number:   1045,
			SQLState: [5]byte{'2', '8', '0', '0', '0'},
			Message:  "Access denied for user",
		}
		target := &mysql.MySQLError{
			Number: 1044,
		}
		if errors.Is(errVal, target) {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected errors.Is to return false for differing Number (1045 vs 1044)\n")
			os.Exit(1)
		}
	}

	// Assertion 5: errors.As successfully unwraps *mysql.MySQLError from wrapped error chain
	{
		origErr := &mysql.MySQLError{
			Number:   1213,
			SQLState: [5]byte{'4', '0', '0', '0', '1'},
			Message:  "Deadlock found when trying to get lock; try restarting transaction",
		}
		wrapped := fmt.Errorf("execution error: %w", origErr)
		var extracted *mysql.MySQLError
		if !errors.As(wrapped, &extracted) {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: errors.As failed to extract *mysql.MySQLError\n")
			os.Exit(1)
		}
		if extracted.Number != 1213 {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: extracted Number %d != 1213\n", extracted.Number)
			os.Exit(1)
		}
	}

	// Assertion 6: errors.Is correctly matches target *mysql.MySQLError through wrapped error chain
	{
		origErr := &mysql.MySQLError{
			Number:   1205,
			SQLState: [5]byte{'H', 'Y', '0', '0', '0'},
			Message:  "Lock wait timeout exceeded; try restarting transaction",
		}
		wrapped := fmt.Errorf("transaction failed: %w", origErr)
		target := &mysql.MySQLError{Number: 1205}
		if !errors.Is(wrapped, target) {
			fmt.Fprintf(os.Stderr, "Assertion 6 failed: errors.Is failed through wrapped error chain\n")
			os.Exit(1)
		}
	}

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