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

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.OverApply 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.OverApply
Required runtime conditions:
  - ecosystem: golang
  - language: go
  - packageManager: go@1.26.6
  - runtime: go@1.26.6

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:a0bc5cd467717d13b930db47899570add5daaf8c95d20beb333527a4f9817ff8","contract":["OverApply parses key-value pairs from an io.Reader and sets new environment variables","OverApply overrides already set environment variables with values from the reader","OverApply evaluates variable substitutions using earlier definitions within the stream","OverApply handles export prefixes and quoted strings with whitespace","OverApply returns an error when encountering malformed input with unclosed quotes"],"goal":"verify github.com/subosito/gotenv.OverApply 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.OverApply"]},"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/github.com/subosito/gotenv@v1.6.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/subosito/gotenv@v1.6.0","symbols":["github.com/subosito/gotenv.OverApply"],"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 sample

import (
	"io"
	"strings"

	"github.com/subosito/gotenv"
)

// ApplyReader parses key-value pairs from an io.Reader and sets environment variables if unset.
func ApplyReader(r io.Reader) error {
	return gotenv.Apply(r)
}

// OverApplyReader parses key-value pairs from an io.Reader and sets or overrides environment variables.
func OverApplyReader(r io.Reader) error {
	return gotenv.OverApply(r)
}

// OverApplyString parses key-value pairs from a string and sets or overrides environment variables.
func OverApplyString(content string) error {
	return gotenv.OverApply(strings.NewReader(content))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/subosito/gotenv.OverApply 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.OverApply"
  ],
  "runtimeConditions": {
    "ecosystem": "golang",
    "language": "go",
    "packageManager": "go@1.26.6",
    "runtime": "go@1.26.6"
  }
}

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/subosito/gotenv"
	"sample"
)

func main() {
	// Assertion 1: OverApply parses key-value pairs from an io.Reader and sets new environment variables
	os.Unsetenv("GOTENV_TEST_VAR1")
	r1 := strings.NewReader("GOTENV_TEST_VAR1=initial_value\n")
	if err := sample.OverApplyReader(r1); err != nil {
		fmt.Fprintf(os.Stderr, "Assertion 1 failed: OverApplyReader returned error: %v\n", err)
		os.Exit(1)
	}
	if got := os.Getenv("GOTENV_TEST_VAR1"); got != "initial_value" {
		fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected 'initial_value', got '%s'\n", got)
		os.Exit(1)
	}

	// Assertion 2: OverApply overrides already set environment variables with values from the reader
	os.Setenv("GOTENV_TEST_OVERRIDE", "original_value")
	if err := sample.ApplyReader(strings.NewReader("GOTENV_TEST_OVERRIDE=ignored_value\n")); err != nil {
		fmt.Fprintf(os.Stderr, "Assertion 2 failed: ApplyReader returned error: %v\n", err)
		os.Exit(1)
	}
	if got := os.Getenv("GOTENV_TEST_OVERRIDE"); got != "original_value" {
		fmt.Fprintf(os.Stderr, "Assertion 2 failed: ApplyReader unexpectedly changed value: got '%s'\n", got)
		os.Exit(1)
	}
	if err := sample.OverApplyReader(strings.NewReader("GOTENV_TEST_OVERRIDE=updated_value\n")); err != nil {
		fmt.Fprintf(os.Stderr, "Assertion 2 failed: OverApplyReader returned error: %v\n", err)
		os.Exit(1)
	}
	if got := os.Getenv("GOTENV_TEST_OVERRIDE"); got != "updated_value" {
		fmt.Fprintf(os.Stderr, "Assertion 2 failed: expected 'updated_value', got '%s'\n", got)
		os.Exit(1)
	}

	// Assertion 3: OverApply evaluates variable substitutions using earlier definitions within the stream
	r3 := "BASE_NAME=world\nFULL_MESSAGE=hello_${BASE_NAME}\n"
	if err := sample.OverApplyString(r3); err != nil {
		fmt.Fprintf(os.Stderr, "Assertion 3 failed: OverApplyString returned error: %v\n", err)
		os.Exit(1)
	}
	if got := os.Getenv("FULL_MESSAGE"); got != "hello_world" {
		fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected 'hello_world', got '%s'\n", got)
		os.Exit(1)
	}

	// Assertion 4: OverApply handles export prefixes and quoted strings with whitespace
	r4 := "# Configuration values\nexport GREETING=\"hello world\"\nSERVER_MODE='production'\n"
	if err := sample.OverApplyString(r4); err != nil {
		fmt.Fprintf(os.Stderr, "Assertion 4 failed: OverApplyString returned error: %v\n", err)
		os.Exit(1)
	}
	if got := os.Getenv("GREETING"); got != "hello world" {
		fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected 'hello world', got '%s'\n", got)
		os.Exit(1)
	}
	if got := os.Getenv("SERVER_MODE"); got != "production" {
		fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected 'production', got '%s'\n", got)
		os.Exit(1)
	}

	// Assertion 5: OverApply returns an error when encountering malformed input with unclosed quotes
	r5 := "BROKEN_VAL=\"unclosed quote string\n"
	if err := gotenv.OverApply(strings.NewReader(r5)); err == nil {
		fmt.Fprintf(os.Stderr, "Assertion 5 failed: expected error for unclosed quotes, got nil\n")
		os.Exit(1)
	}

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