github.com/subosito/gotenv v1.6.0: Apply

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/subosito/gotenv.Apply in pkg:golang/github.com/subosito/gotenv@v1.6.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/subosito/gotenv@v1.6.0
Demonstrate these symbols/APIs:
  - github.com/subosito/gotenv.Apply

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:d00aff4ff0d0688684ab70c1fa365c3f9f50ba904f88756e46627c011d410076","contract":["gotenv.Apply parses key-value pairs from an io.Reader and sets them as environment variables if unset","gotenv.Apply does not overwrite existing environment variables","gotenv.Apply ignores empty lines and comment lines starting with hash","gotenv.Apply parses export syntax and quoted values containing spaces"],"goal":"verify github.com/subosito/gotenv.Apply in pkg:golang/github.com/subosito/gotenv@v1.6.0","kind":"HOW","packages":["pkg:golang/github.com/subosito/gotenv@v1.6.0"],"schemaVersion":1,"symbols":["github.com/subosito/gotenv.Apply"]},"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/subosito/gotenv@v1.6.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/subosito/gotenv@v1.6.0","symbols":["github.com/subosito/gotenv.Apply"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/subosito/gotenv v1.6.0

require golang.org/x/text v0.12.0 // indirect

github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.7.5 h1:s5PTfem8p8EbKQOctVV53k6jCJt3UX4IEJzwh+C324Q=
github.com/stretchr/testify v1.7.5/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=
github.com/subosito/gotenv v1.6.0/go.mod h1:Dk4QP5c2W3ibzajGcXpNraDfq2IrhjMIvMSWPKKo0FU=
golang.org/x/text v0.12.0 h1:k+n5B8goJNdU7hSvEtMUz3d1Q6D/XW4COJSJR6fN0mc=
golang.org/x/text v0.12.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/subosito/gotenv"
)

func main() {
	input := "APP_ENV=production\nAPP_PORT=8080\n"
	err := gotenv.Apply(strings.NewReader(input))
	if err != nil {
		fmt.Fprintf(os.Stderr, "gotenv.Apply failed: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Configured environment: APP_ENV=%s, APP_PORT=%s\n", os.Getenv("APP_ENV"), os.Getenv("APP_PORT"))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/subosito/gotenv.Apply in pkg:golang/github.com/subosito/gotenv@v1.6.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/subosito/gotenv@v1.6.0"
  ],
  "symbols": [
    "github.com/subosito/gotenv.Apply"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/subosito/gotenv"
)

func main() {
	// Assertion 1: gotenv.Apply parses key-value pairs from an io.Reader and sets them as environment variables if unset
	{
		key := "CSX_TEST_VAR_A"
		expected := "value_a"
		os.Unsetenv(key)

		input := fmt.Sprintf("%s=%s\n", key, expected)
		err := gotenv.Apply(strings.NewReader(input))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if got := os.Getenv(key); got != expected {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

	// Assertion 2: gotenv.Apply does not overwrite existing environment variables
	{
		key := "CSX_TEST_VAR_PREEXISTING"
		initialVal := "initial_value"
		attemptedVal := "overwritten_value"
		os.Setenv(key, initialVal)

		input := fmt.Sprintf("%s=%s\n", key, attemptedVal)
		err := gotenv.Apply(strings.NewReader(input))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if got := os.Getenv(key); got != initialVal {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: gotenv.Apply should not overwrite existing env, expected %q, got %q\n", initialVal, got)
			os.Exit(1)
		}
	}

	// Assertion 3: gotenv.Apply ignores empty lines and comment lines starting with hash
	{
		key := "CSX_TEST_VAR_COMMENTED"
		expected := "active_value"
		os.Unsetenv(key)
		os.Unsetenv("IGNORED_COMMENT")

		input := `
# IGNORED_COMMENT=not_set
# This is a comment line

` + key + "=" + expected + "\n\n"

		err := gotenv.Apply(strings.NewReader(input))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if got := os.Getenv(key); got != expected {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
		if got := os.Getenv("IGNORED_COMMENT"); got != "" {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: comment line should be ignored, got %q\n", got)
			os.Exit(1)
		}
	}

	// Assertion 4: gotenv.Apply parses export syntax and quoted values containing spaces
	{
		key := "CSX_TEST_VAR_QUOTED"
		expected := "quoted value with spaces"
		os.Unsetenv(key)

		input := fmt.Sprintf("export %s=%q\n", key, expected)
		err := gotenv.Apply(strings.NewReader(input))
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if got := os.Getenv(key); got != expected {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

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