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

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.NewConfig 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.NewConfig
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:a1929eaf54ba8db2bfb8ff910feba49828db573e969484b95d74f261f07e61f0","contract":["mysql.NewConfig returns a non-nil *mysql.Config initialized with default collation utf8mb4_general_ci, UTC location, AllowNativePasswords true, and CheckConnLiveness true","mysql.NewConfig sets default MaxAllowedPacket to 67108864 (64MB)","mysql.NewConfig creates an empty-credential Config that formats to a valid base DSN and can be customized with User, Passwd, Net, Addr, and DBName","mysql.Config.Clone returns an independent deep copy of the configuration where modifying cloned properties and Params map does not mutate the original","mysql.Config.FormatDSN formats extended connection options such as ParseTime and Timeout which can be round-trip parsed by mysql.ParseDSN"],"goal":"verify github.com/go-sql-driver/mysql.NewConfig 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.NewConfig"]},"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.NewConfig"],"verifierAdapter":"golang@1"}

module sample-mysql-newconfig

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 (
	"fmt"
	"time"

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

func main() {
	// Initialize default configuration
	cfg := mysql.NewConfig()

	// Inspect default properties configured by NewConfig
	fmt.Printf("Default collation: %s\n", cfg.Collation)
	fmt.Printf("Default location: %v\n", cfg.Loc)
	fmt.Printf("Native passwords allowed: %t\n", cfg.AllowNativePasswords)
	fmt.Printf("Connection liveness checked: %t\n", cfg.CheckConnLiveness)
	fmt.Printf("Max allowed packet: %d\n", cfg.MaxAllowedPacket)

	// Customize connection parameters
	cfg.User = "appuser"
	cfg.Passwd = "secret"
	cfg.Net = "tcp"
	cfg.Addr = "127.0.0.1:3306"
	cfg.DBName = "appdb"
	cfg.ParseTime = true
	cfg.Timeout = 5 * time.Second

	// Format DSN string
	dsn := cfg.FormatDSN()
	fmt.Printf("Formatted DSN: %s\n", dsn)

	// Clone configuration to create an independent copy
	clonedCfg := cfg.Clone()
	clonedCfg.DBName = "testdb"
	fmt.Printf("Original DB: %s, Cloned DB: %s\n", cfg.DBName, clonedCfg.DBName)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/go-sql-driver/mysql.NewConfig 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.NewConfig"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"
	"time"

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

func main() {
	// Assertion 1: mysql.NewConfig returns a non-nil *mysql.Config initialized with default collation utf8mb4_general_ci, UTC location, AllowNativePasswords true, and CheckConnLiveness true
	{
		cfg := mysql.NewConfig()
		if cfg == nil {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: mysql.NewConfig returned nil\n")
			os.Exit(1)
		}
		if cfg.Collation != "utf8mb4_general_ci" {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected Collation 'utf8mb4_general_ci', got %q\n", cfg.Collation)
			os.Exit(1)
		}
		if cfg.Loc != time.UTC {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected Loc UTC, got %v\n", cfg.Loc)
			os.Exit(1)
		}
		if !cfg.AllowNativePasswords {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected AllowNativePasswords to be true\n")
			os.Exit(1)
		}
		if !cfg.CheckConnLiveness {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected CheckConnLiveness to be true\n")
			os.Exit(1)
		}
	}

	// Assertion 2: mysql.NewConfig sets default MaxAllowedPacket to 67108864 (64MB)
	{
		cfg := mysql.NewConfig()
		if cfg.MaxAllowedPacket != 67108864 {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: expected MaxAllowedPacket 67108864, got %d\n", cfg.MaxAllowedPacket)
			os.Exit(1)
		}
	}

	// Assertion 3: mysql.NewConfig creates an empty-credential Config that formats to a valid base DSN and can be customized with User, Passwd, Net, Addr, and DBName
	{
		cfg := mysql.NewConfig()
		cfg.User = "dbuser"
		cfg.Passwd = "dbpass"
		cfg.Net = "tcp"
		cfg.Addr = "127.0.0.1:3306"
		cfg.DBName = "testdb"

		expectedDSN := "dbuser:dbpass@tcp(127.0.0.1:3306)/testdb"
		if dsn := cfg.FormatDSN(); dsn != expectedDSN {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected DSN %q, got %q\n", expectedDSN, dsn)
			os.Exit(1)
		}
	}

	// Assertion 4: mysql.Config.Clone returns an independent deep copy of the configuration where modifying cloned properties and Params map does not mutate the original
	{
		orig := mysql.NewConfig()
		orig.User = "root"
		orig.DBName = "production"
		orig.Params = map[string]string{
			"charset": "utf8mb4",
		}

		cloned := orig.Clone()
		if cloned.User != "root" || cloned.DBName != "production" {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: clone field mismatch\n")
			os.Exit(1)
		}

		cloned.DBName = "staging"
		cloned.Params["charset"] = "latin1"
		cloned.Params["custom"] = "value"

		if orig.DBName != "production" {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: mutating clone modified original DBName\n")
			os.Exit(1)
		}
		if orig.Params["charset"] != "utf8mb4" || len(orig.Params) != 1 {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: mutating clone params modified original params\n")
			os.Exit(1)
		}
	}

	// Assertion 5: mysql.Config.FormatDSN formats extended connection options such as ParseTime and Timeout which can be round-trip parsed by mysql.ParseDSN
	{
		cfg := mysql.NewConfig()
		cfg.User = "app"
		cfg.Passwd = "secret"
		cfg.Net = "tcp"
		cfg.Addr = "localhost:3306"
		cfg.DBName = "appdb"
		cfg.ParseTime = true
		cfg.Timeout = 10 * time.Second

		dsn := cfg.FormatDSN()
		parsed, err := mysql.ParseDSN(dsn)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: mysql.ParseDSN failed on formatted DSN: %v\n", err)
			os.Exit(1)
		}
		if parsed.User != cfg.User || parsed.Passwd != cfg.Passwd || parsed.Net != cfg.Net || parsed.Addr != cfg.Addr || parsed.DBName != cfg.DBName {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: parsed credentials/target mismatch\n")
			os.Exit(1)
		}
		if !parsed.ParseTime {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: expected ParseTime true in parsed config\n")
			os.Exit(1)
		}
		if parsed.Timeout != 10*time.Second {
			fmt.Fprintf(os.Stderr, "Assertion 5 failed: expected Timeout 10s, got %v\n", parsed.Timeout)
			os.Exit(1)
		}
	}

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