golang.org/x/net v0.0.0-20190311183353-d8887717615a: httpproxy.FromEnvironment

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 golang.org/x/net/http/httpproxy.FromEnvironment in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a
Demonstrate these symbols/APIs:
  - golang.org/x/net/http/httpproxy.FromEnvironment

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:e45009767fa2b4d8b134bcdb5214336a5c5fd7ca30409083aa52c59e5d86108f","contract":["httpproxy.FromEnvironment initializes proxy configuration from HTTP_PROXY, HTTPS_PROXY, and NO_PROXY environment variables","httpproxy.FromEnvironment returns a Config whose ProxyFunc routes URLs according to environment proxy settings while respecting NO_PROXY"],"goal":"verify golang.org/x/net/http/httpproxy.FromEnvironment in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a"],"schemaVersion":1,"symbols":["golang.org/x/net/http/httpproxy.FromEnvironment"]},"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/golang.org/x/net@v0.0.0-20190311183353-d8887717615a"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a","symbols":["golang.org/x/net/http/httpproxy.FromEnvironment"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require golang.org/x/net v0.0.0-20190311183353-d8887717615a

require golang.org/x/text v0.3.0 // indirect

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20190311183353-d8887717615a h1:oWX7TPOiFAMXLq8o0ikBYfCJVlRHBcsciT5bXOrH628=
golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

package main

import (
	"fmt"
	"net/url"
	"os"

	"golang.org/x/net/http/httpproxy"
)

func main() {
	os.Setenv("HTTP_PROXY", "http://proxy.example.com:8080")
	os.Setenv("HTTPS_PROXY", "https://proxy.example.com:8443")
	os.Setenv("NO_PROXY", "localhost,127.0.0.1,bypass.example.com")
	defer func() {
		os.Unsetenv("HTTP_PROXY")
		os.Unsetenv("HTTPS_PROXY")
		os.Unsetenv("NO_PROXY")
	}()

	cfg := httpproxy.FromEnvironment()
	fmt.Printf("Configured HTTP_PROXY: %s\n", cfg.HTTPProxy)
	fmt.Printf("Configured HTTPS_PROXY: %s\n", cfg.HTTPSProxy)
	fmt.Printf("Configured NO_PROXY: %s\n", cfg.NoProxy)

	proxyFunc := cfg.ProxyFunc()

	targetURL, err := url.Parse("http://external.example.com/data")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to parse target url: %v\n", err)
		os.Exit(1)
	}

	proxyURL, err := proxyFunc(targetURL)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to determine proxy: %v\n", err)
		os.Exit(1)
	}

	if proxyURL != nil {
		fmt.Printf("Routing %s via %s\n", targetURL, proxyURL)
	} else {
		fmt.Printf("Routing %s directly\n", targetURL)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/http/httpproxy.FromEnvironment in pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20190311183353-d8887717615a"
  ],
  "symbols": [
    "golang.org/x/net/http/httpproxy.FromEnvironment"
  ]
}

package main

import (
	"fmt"
	"net/url"
	"os"

	"golang.org/x/net/http/httpproxy"
)

func main() {
	// Assertion 1: httpproxy.FromEnvironment initializes proxy configuration from HTTP_PROXY, HTTPS_PROXY, and NO_PROXY environment variables
	{
		os.Setenv("HTTP_PROXY", "http://env-proxy.example.com:8080")
		os.Setenv("HTTPS_PROXY", "https://env-proxy.example.com:8443")
		os.Setenv("NO_PROXY", "bypass.example.com,127.0.0.1")
		defer func() {
			os.Unsetenv("HTTP_PROXY")
			os.Unsetenv("HTTPS_PROXY")
			os.Unsetenv("NO_PROXY")
		}()

		cfg := httpproxy.FromEnvironment()
		if cfg.HTTPProxy != "http://env-proxy.example.com:8080" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected HTTPProxy %q, got %q\n", "http://env-proxy.example.com:8080", cfg.HTTPProxy)
			os.Exit(1)
		}
		if cfg.HTTPSProxy != "https://env-proxy.example.com:8443" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected HTTPSProxy %q, got %q\n", "https://env-proxy.example.com:8443", cfg.HTTPSProxy)
			os.Exit(1)
		}
		if cfg.NoProxy != "bypass.example.com,127.0.0.1" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected NoProxy %q, got %q\n", "bypass.example.com,127.0.0.1", cfg.NoProxy)
			os.Exit(1)
		}
	}

	// Assertion 2: httpproxy.FromEnvironment returns a Config whose ProxyFunc routes URLs according to environment proxy settings while respecting NO_PROXY
	{
		os.Setenv("HTTP_PROXY", "http://env-proxy.example.com:8080")
		os.Setenv("HTTPS_PROXY", "https://env-proxy.example.com:8443")
		os.Setenv("NO_PROXY", "bypass.example.com,127.0.0.1")
		defer func() {
			os.Unsetenv("HTTP_PROXY")
			os.Unsetenv("HTTPS_PROXY")
			os.Unsetenv("NO_PROXY")
		}()

		cfg := httpproxy.FromEnvironment()
		proxyFunc := cfg.ProxyFunc()

		// Case A: HTTP URL to external domain -> routes via HTTPProxy
		targetHTTP, err := url.Parse("http://external.example.com/api")
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: url parse error: %v\n", err)
			os.Exit(1)
		}
		proxyHTTP, err := proxyFunc(targetHTTP)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: proxyFunc returned error: %v\n", err)
			os.Exit(1)
		}
		if proxyHTTP == nil || proxyHTTP.String() != "http://env-proxy.example.com:8080" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected proxy %q, got %v\n", "http://env-proxy.example.com:8080", proxyHTTP)
			os.Exit(1)
		}

		// Case B: HTTPS URL to external domain -> routes via HTTPSProxy
		targetHTTPS, err := url.Parse("https://external.example.com/secure")
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: url parse error: %v\n", err)
			os.Exit(1)
		}
		proxyHTTPS, err := proxyFunc(targetHTTPS)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: proxyFunc returned error: %v\n", err)
			os.Exit(1)
		}
		if proxyHTTPS == nil || proxyHTTPS.String() != "https://env-proxy.example.com:8443" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected proxy %q, got %v\n", "https://env-proxy.example.com:8443", proxyHTTPS)
			os.Exit(1)
		}

		// Case C: Target matching NO_PROXY -> bypasses proxy (nil)
		targetBypass, err := url.Parse("http://bypass.example.com/status")
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: url parse error: %v\n", err)
			os.Exit(1)
		}
		proxyBypass, err := proxyFunc(targetBypass)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: proxyFunc returned error: %v\n", err)
			os.Exit(1)
		}
		if proxyBypass != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected bypass (nil), got %v\n", proxyBypass)
			os.Exit(1)
		}
	}

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