github.com/julienschmidt/httprouter v1.3.0: New

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/julienschmidt/httprouter.New in 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
Demonstrate these symbols/APIs:
  - github.com/julienschmidt/httprouter.New

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:sha256:75c1720e916549a3be2c43797337c2de31f142707aed07186c495ee861c400e0","contract":["httprouter.New returns a non-nil *httprouter.Router implementing http.Handler","httprouter.New router dispatches GET requests and resolves named route parameters via Params.ByName","httprouter.New router dispatches POST requests and passes execution to registered handle","httprouter.New router triggers custom NotFound handler for unmatched paths","httprouter.New router handles MethodNotAllowed with 405 status code for mismatched HTTP methods"],"goal":"verify github.com/julienschmidt/httprouter.New in pkg:golang/github.com/julienschmidt/httprouter@v1.3.0","kind":"HOW","packages":["pkg:golang/github.com/julienschmidt/httprouter@v1.3.0"],"schemaVersion":1,"symbols":["github.com/julienschmidt/httprouter.New"]},"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/julienschmidt/httprouter@v1.3.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/julienschmidt/httprouter@v1.3.0","symbols":["github.com/julienschmidt/httprouter.New"],"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 := httptest.NewRequest(http.MethodGet, "/hello/gopher", nil)
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	fmt.Printf("Status: %d, Response: %s", rec.Code, rec.Body.String())
}

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

package main

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

	"github.com/julienschmidt/httprouter"
)

func main() {
	if err := runContract(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract verification failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All httprouter.New contract assertions passed successfully.")
}

func runContract() error {
	// Assertion 1: httprouter.New returns a non-nil *httprouter.Router implementing http.Handler
	router := httprouter.New()
	if router == nil {
		return fmt.Errorf("assertion 1 failed: httprouter.New returned nil")
	}
	var _ http.Handler = router

	// Assertion 2: httprouter.New router dispatches GET requests and resolves named route parameters via Params.ByName
	var capturedName string
	router.GET("/users/:name", func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
		capturedName = ps.ByName("name")
		w.WriteHeader(http.StatusOK)
		fmt.Fprintf(w, "user:%s", capturedName)
	})

	reqGet := httptest.NewRequest(http.MethodGet, "/users/alice", nil)
	recGet := httptest.NewRecorder()
	router.ServeHTTP(recGet, reqGet)

	if recGet.Code != http.StatusOK {
		return fmt.Errorf("assertion 2 failed: expected status %d, got %d", http.StatusOK, recGet.Code)
	}
	if capturedName != "alice" {
		return fmt.Errorf("assertion 2 failed: expected captured param 'alice', got %q", capturedName)
	}
	if recGet.Body.String() != "user:alice" {
		return fmt.Errorf("assertion 2 failed: expected body 'user:alice', got %q", recGet.Body.String())
	}

	// Assertion 3: httprouter.New router dispatches POST requests and passes execution to registered handle
	var postExecuted bool
	router.POST("/items", func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
		postExecuted = true
		w.WriteHeader(http.StatusCreated)
		fmt.Fprint(w, "created")
	})

	reqPost := httptest.NewRequest(http.MethodPost, "/items", nil)
	recPost := httptest.NewRecorder()
	router.ServeHTTP(recPost, reqPost)

	if recPost.Code != http.StatusCreated {
		return fmt.Errorf("assertion 3 failed: expected status %d, got %d", http.StatusCreated, recPost.Code)
	}
	if !postExecuted {
		return fmt.Errorf("assertion 3 failed: POST handler was not executed")
	}
	if recPost.Body.String() != "created" {
		return fmt.Errorf("assertion 3 failed: expected body 'created', got %q", recPost.Body.String())
	}

	// Assertion 4: httprouter.New router triggers custom NotFound handler for unmatched paths
	var notFoundTriggered bool
	router.NotFound = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		notFoundTriggered = true
		http.Error(w, "custom not found", http.StatusNotFound)
	})

	reqNotFound := httptest.NewRequest(http.MethodGet, "/unregistered/path", nil)
	recNotFound := httptest.NewRecorder()
	router.ServeHTTP(recNotFound, reqNotFound)

	if recNotFound.Code != http.StatusNotFound {
		return fmt.Errorf("assertion 4 failed: expected status %d, got %d", http.StatusNotFound, recNotFound.Code)
	}
	if !notFoundTriggered {
		return fmt.Errorf("assertion 4 failed: custom NotFound handler was not triggered")
	}

	// Assertion 5: httprouter.New router handles MethodNotAllowed with 405 status code for mismatched HTTP methods
	reqMethodNotAllowed := httptest.NewRequest(http.MethodPut, "/items", nil)
	recMethodNotAllowed := httptest.NewRecorder()
	router.ServeHTTP(recMethodNotAllowed, reqMethodNotAllowed)

	if recMethodNotAllowed.Code != http.StatusMethodNotAllowed {
		return fmt.Errorf("assertion 5 failed: expected status %d, got %d", http.StatusMethodNotAllowed, recMethodNotAllowed.Code)
	}

	return nil
}