github.com/julienschmidt/httprouter v1.3.0

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 pkg:golang/github.com/julienschmidt/httprouter@v1.3.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/julienschmidt/httprouter@v1.3.0

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:sha256:5a67f1228e6ced519199b73714595422d6d9c03641dde358899239c13ea88f6f","contract":["httprouter.New returns an initialized Router","Router.GET routes GET requests with named path parameters","Router.POST routes POST requests with body content","Router.NotFound executes custom handler for unmatched routes","Router.PanicHandler intercepts panics during request handling"],"goal":"verify pkg:golang/github.com/julienschmidt/httprouter@v1.3.0","kind":"HOW","packages":["pkg:golang/github.com/julienschmidt/httprouter@v1.3.0"],"schemaVersion":1},"contractCommand":["go","run","./test"],"environment":{"arch":"amd64","compiler":"go","compilerVersion":"1.26.6","distro":"ubuntu","ecosystem":"golang","language":"go","languageVersion":"1.26.6","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/julienschmidt/httprouter@v1.3.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/julienschmidt/httprouter@v1.3.0","verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/julienschmidt/httprouter v1.3.0

github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=

package main

import (
	"fmt"
	"net/http"
	"net/http/httptest"

	"github.com/julienschmidt/httprouter"
)

func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
	fmt.Fprint(w, "Welcome!\n")
}

func Hello(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
	fmt.Fprintf(w, "hello, %s!\n", ps.ByName("name"))
}

func main() {
	router := httprouter.New()
	router.GET("/", Index)
	router.GET("/hello/:name", Hello)

	req, _ := http.NewRequest("GET", "/hello/gopher", nil)
	rr := httptest.NewRecorder()
	router.ServeHTTP(rr, req)

	fmt.Printf("Response: %s", rr.Body.String())
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/julienschmidt/httprouter@v1.3.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/julienschmidt/httprouter@v1.3.0"
  ]
}

package main

import (
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"

	"github.com/julienschmidt/httprouter"
)

func main() {
	// Assertion 1: httprouter.New returns an initialized Router
	{
		router := httprouter.New()
		if router == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: router is nil\n")
			os.Exit(1)
		}
		var _ http.Handler = router
	}

	// Assertion 2: Router.GET routes GET requests with named path parameters
	{
		router := httprouter.New()
		var capturedParam string
		router.GET("/users/:id", func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
			capturedParam = ps.ByName("id")
			w.WriteHeader(http.StatusOK)
			fmt.Fprint(w, "user-found")
		})

		req := httptest.NewRequest("GET", "/users/42", nil)
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if rec.Code != http.StatusOK {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected status 200, got %d\n", rec.Code)
			os.Exit(1)
		}
		if capturedParam != "42" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected param '42', got %q\n", capturedParam)
			os.Exit(1)
		}
		if rec.Body.String() != "user-found" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected body 'user-found', got %q\n", rec.Body.String())
			os.Exit(1)
		}
	}

	// Assertion 3: Router.POST routes POST requests with body content
	{
		router := httprouter.New()
		var receivedBody string
		router.POST("/submit", func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
			b, err := io.ReadAll(r.Body)
			if err != nil {
				w.WriteHeader(http.StatusInternalServerError)
				return
			}
			receivedBody = string(b)
			w.WriteHeader(http.StatusCreated)
		})

		payload := "item=alpha"
		req := httptest.NewRequest("POST", "/submit", strings.NewReader(payload))
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if rec.Code != http.StatusCreated {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected status 201, got %d\n", rec.Code)
			os.Exit(1)
		}
		if receivedBody != payload {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected body %q, got %q\n", payload, receivedBody)
			os.Exit(1)
		}
	}

	// Assertion 4: Router.NotFound executes custom handler for unmatched routes
	{
		router := httprouter.New()
		customNotFoundCalled := false
		router.NotFound = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			customNotFoundCalled = true
			w.WriteHeader(http.StatusNotFound)
			fmt.Fprint(w, "custom-404")
		})

		req := httptest.NewRequest("GET", "/nonexistent", nil)
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if !customNotFoundCalled {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: custom NotFound handler not called\n")
			os.Exit(1)
		}
		if rec.Code != http.StatusNotFound {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected status 404, got %d\n", rec.Code)
			os.Exit(1)
		}
		if rec.Body.String() != "custom-404" {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected body 'custom-404', got %q\n", rec.Body.String())
			os.Exit(1)
		}
	}

	// Assertion 5: Router.PanicHandler intercepts panics during request handling
	{
		router := httprouter.New()
		panicCaught := false
		router.PanicHandler = func(w http.ResponseWriter, r *http.Request, p interface{}) {
			panicCaught = true
			w.WriteHeader(http.StatusInternalServerError)
			fmt.Fprint(w, "recovered")
		}
		router.GET("/panic", func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
			panic("something went wrong")
		})

		req := httptest.NewRequest("GET", "/panic", nil)
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if !panicCaught {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: panic was not caught\n")
			os.Exit(1)
		}
		if rec.Code != http.StatusInternalServerError {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected status 500, got %d\n", rec.Code)
			os.Exit(1)
		}
		if rec.Body.String() != "recovered" {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected body 'recovered', got %q\n", rec.Body.String())
			os.Exit(1)
		}
	}

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