github.com/matttproud/golang_protobuf_extensions v1.0.1: pbutil.ReadDelimited, pbutil.WriteDelimited

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/matttproud/golang_protobuf_extensions@v1.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1
Demonstrate these symbols/APIs:
  - pbutil.ReadDelimited
  - pbutil.WriteDelimited

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:b7267bca5e38ddff7821adbdd97162ee5a32918a17f93478be0759df19eff43a","contract":["pbutil.WriteDelimited encodes and writes length-delimited protobuf message to io.Writer.","pbutil.ReadDelimited reads and decodes length-delimited protobuf message from io.Reader.","pbutil.ReadDelimited returns io.EOF when reader has no more data.","pbutil.ReadDelimited returns error when reader contains truncated data."],"goal":"verify pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1","kind":"HOW","packages":["pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1"],"schemaVersion":1,"symbols":["pbutil.ReadDelimited","pbutil.WriteDelimited"]},"contractCommand":["go","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/matttproud/golang_protobuf_extensions@v1.0.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1","symbols":["pbutil.ReadDelimited","pbutil.WriteDelimited"],"verifierAdapter":"golang@1"}

module example.com/protobuf-delimited

go 1.26.6

require (
	github.com/golang/protobuf v1.5.4
	github.com/matttproud/golang_protobuf_extensions v1.0.1
)

require google.golang.org/protobuf v1.33.0 // indirect

github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

package main

import (
	"bytes"
	"fmt"
	"io"

	"github.com/golang/protobuf/ptypes/wrappers"
	"github.com/matttproud/golang_protobuf_extensions/pbutil"
)

func main() {
	var buf bytes.Buffer

	// Write delimited protobuf messages
	msg1 := &wrappers.StringValue{Value: "first payload"}
	msg2 := &wrappers.StringValue{Value: "second payload"}

	n1, err := pbutil.WriteDelimited(&buf, msg1)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Wrote message 1 (%d bytes)\n", n1)

	n2, err := pbutil.WriteDelimited(&buf, msg2)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Wrote message 2 (%d bytes)\n", n2)

	// Read delimited protobuf messages back
	var out1 wrappers.StringValue
	r1, err := pbutil.ReadDelimited(&buf, &out1)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Read message 1 (%d bytes): %s\n", r1, out1.GetValue())

	var out2 wrappers.StringValue
	r2, err := pbutil.ReadDelimited(&buf, &out2)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Read message 2 (%d bytes): %s\n", r2, out2.GetValue())

	// Read past end returns EOF
	var out3 wrappers.StringValue
	_, err = pbutil.ReadDelimited(&buf, &out3)
	if err == io.EOF {
		fmt.Println("Reached end of stream (EOF)")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/matttproud/golang_protobuf_extensions@v1.0.1"
  ],
  "symbols": [
    "pbutil.ReadDelimited",
    "pbutil.WriteDelimited"
  ]
}

package test

import (
	"bytes"
	"io"
	"testing"

	"github.com/golang/protobuf/ptypes/wrappers"
	"github.com/matttproud/golang_protobuf_extensions/pbutil"
)

func TestWriteAndReadDelimited(t *testing.T) {
	var buf bytes.Buffer

	msg1 := &wrappers.StringValue{Value: "hello world"}
	msg2 := &wrappers.StringValue{Value: "another message"}

	n1, err := pbutil.WriteDelimited(&buf, msg1)
	if err != nil {
		t.Fatalf("WriteDelimited(msg1) failed: %v", err)
	}
	if n1 <= 0 {
		t.Fatalf("WriteDelimited(msg1) returned byte count <= 0: %d", n1)
	}

	n2, err := pbutil.WriteDelimited(&buf, msg2)
	if err != nil {
		t.Fatalf("WriteDelimited(msg2) failed: %v", err)
	}
	if n2 <= 0 {
		t.Fatalf("WriteDelimited(msg2) returned byte count <= 0: %d", n2)
	}

	var read1 wrappers.StringValue
	r1, err := pbutil.ReadDelimited(&buf, &read1)
	if err != nil {
		t.Fatalf("ReadDelimited(read1) failed: %v", err)
	}
	if r1 != n1 {
		t.Errorf("ReadDelimited read %d bytes, want %d bytes", r1, n1)
	}
	if read1.GetValue() != "hello world" {
		t.Errorf("read1.GetValue() = %q, want %q", read1.GetValue(), "hello world")
	}

	var read2 wrappers.StringValue
	r2, err := pbutil.ReadDelimited(&buf, &read2)
	if err != nil {
		t.Fatalf("ReadDelimited(read2) failed: %v", err)
	}
	if r2 != n2 {
		t.Errorf("ReadDelimited read %d bytes, want %d bytes", r2, n2)
	}
	if read2.GetValue() != "another message" {
		t.Errorf("read2.GetValue() = %q, want %q", read2.GetValue(), "another message")
	}
}

func TestReadDelimitedEOF(t *testing.T) {
	emptyBuf := bytes.NewReader([]byte{})
	var msg wrappers.StringValue
	n, err := pbutil.ReadDelimited(emptyBuf, &msg)
	if err != io.EOF {
		t.Errorf("ReadDelimited on empty reader expected io.EOF, got %v", err)
	}
	if n != 0 {
		t.Errorf("ReadDelimited on empty reader returned %d bytes, want 0", n)
	}
}

func TestReadDelimitedTruncated(t *testing.T) {
	// A varint header indicating a 20-byte payload, but only 3 bytes provided
	truncatedData := []byte{20, 1, 2, 3}
	reader := bytes.NewReader(truncatedData)
	var msg wrappers.StringValue
	_, err := pbutil.ReadDelimited(reader, &msg)
	if err == nil {
		t.Fatal("ReadDelimited on truncated data expected error, got nil")
	}
}