google.golang.org/genproto/googleapis/bytestream v0.0.0-20260311181403-84a4fc48630c: ByteStream_ReadServer

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 google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer in pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c
Demonstrate these symbols/APIs:
  - google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer

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:fd4243e7f9ad171e6ac55ef5f46c26b36c0582d5959bb70a63297c94b314764d","contract":["ByteStream_ReadServer.Send delivers ReadResponse chunks respecting ReadRequest offset and limit","ByteStream_ReadServer propagates errors returned by Send to the caller","UnimplementedByteStreamServer.Read accepts ByteStream_ReadServer and returns an unimplemented error"],"goal":"verify google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer in pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c","kind":"HOW","packages":["pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c"],"schemaVersion":1,"symbols":["google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer"]},"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/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c"],"schemaVersion":1,"subject":"pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c","symbols":["google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require google.golang.org/genproto/googleapis/bytestream v0.0.0-20260311181403-84a4fc48630c

require (
	golang.org/x/net v0.38.0 // indirect
	golang.org/x/sys v0.31.0 // indirect
	golang.org/x/text v0.23.0 // indirect
	google.golang.org/genproto/googleapis/rpc v0.0.0-20250313205543-e70fdf4c4cb4 // indirect
	google.golang.org/grpc v1.71.0 // indirect
	google.golang.org/protobuf v1.36.11 // indirect
)

github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
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 v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.34.0 h1:zRLXxLCgL1WyKsPVrgbSdMN4c0FMkDAskSTQP+0hdUY=
go.opentelemetry.io/otel v1.34.0/go.mod h1:OWFPOQ+h4G8xpyjgqo4SxJYdDQ/qmRH+wivy7zzx9oI=
go.opentelemetry.io/otel/metric v1.34.0 h1:+eTR3U0MyfWjRDhmFMxe2SsW64QrZ84AOhvqS7Y+PoQ=
go.opentelemetry.io/otel/metric v1.34.0/go.mod h1:CEDrp0fy2D0MvkXE+dPV7cMi8tWZwX3dmaIhwPOaqHE=
go.opentelemetry.io/otel/sdk v1.34.0 h1:95zS4k/2GOy069d321O8jWgYsW3MzVV+KuSPKp7Wr1A=
go.opentelemetry.io/otel/sdk v1.34.0/go.mod h1:0e/pNiaMAqaykJGKbi+tSjWfNNHMTxoC9qANsCzbyxU=
go.opentelemetry.io/otel/sdk/metric v1.34.0 h1:5CeK9ujjbFVL5c1PhLuStg1wxA7vQv7ce1EK0Gyvahk=
go.opentelemetry.io/otel/sdk/metric v1.34.0/go.mod h1:jQ/r8Ze28zRKoNRdkjCZxfs6YvBTG1+YIqyFVFYec5w=
go.opentelemetry.io/otel/trace v1.34.0 h1:+ouXS2V8Rd4hp4580a8q23bg0azF2nI8cqLYnC8mh/k=
go.opentelemetry.io/otel/trace v1.34.0/go.mod h1:Svm7lSjQD7kG7KJ/MUHPVXSDGz2OX4h0M2jHBhmSfRE=
golang.org/x/net v0.38.0 h1:vRMAPTMaeGqVhG5QyLJHqNDwecKTomGeqbnfZyKlBI8=
golang.org/x/net v0.38.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/text v0.23.0 h1:D71I7dUrlY+VX0gQShAThNGHFxZ13dGLBHQLVl1mJlY=
golang.org/x/text v0.23.0/go.mod h1:/BLNzu4aZCJ1+kcD0DNRotWKage4q2rGVAg4o22unh4=
google.golang.org/genproto/googleapis/bytestream v0.0.0-20260311181403-84a4fc48630c h1:+1ZxApUanSjTO3aa1JTnk8zG+lZsZyRCZYhLj2lY8l0=
google.golang.org/genproto/googleapis/bytestream v0.0.0-20260311181403-84a4fc48630c/go.mod h1:9amqk/8LQWEC4RjyUxMx1DebyQ7hZB9gvl67bHmgZ2E=
google.golang.org/genproto/googleapis/rpc v0.0.0-20250313205543-e70fdf4c4cb4 h1:iK2jbkWL86DXjEx0qiHcRE9dE4/Ahua5k6V8OWFb//c=
google.golang.org/genproto/googleapis/rpc v0.0.0-20250313205543-e70fdf4c4cb4/go.mod h1:LuRYeWDFV6WOn90g357N17oMCaxpgCnbi/44qJvDn2I=
google.golang.org/grpc v1.71.0 h1:kF77BGdPTQ4/JZWMlb9VpJ5pa25aqvVqogsxNHHdeBg=
google.golang.org/grpc v1.71.0/go.mod h1:H0GRtasmQOh9LkFoCPDu3ZrwUtD1YGE+b2vYBYd/8Ec=
google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=

package sample

import (
	"bytes"
	"errors"

	"google.golang.org/genproto/googleapis/bytestream"
)

// MemoryReadServer implements bytestream.ByteStream_ReadServer for in-memory verification.
type MemoryReadServer struct {
	bytestream.ByteStream_ReadServer
	Responses []*bytestream.ReadResponse
	SendErr   error
}

// Send records each ReadResponse sent to the ByteStream_ReadServer stream.
func (m *MemoryReadServer) Send(resp *bytestream.ReadResponse) error {
	if m.SendErr != nil {
		return m.SendErr
	}
	cloned := &bytestream.ReadResponse{
		Data: append([]byte(nil), resp.GetData()...),
	}
	m.Responses = append(m.Responses, cloned)
	return nil
}

// CollectedBytes concatenates all data chunks received by the stream.
func (m *MemoryReadServer) CollectedBytes() []byte {
	var buf bytes.Buffer
	for _, r := range m.Responses {
		buf.Write(r.GetData())
	}
	return buf.Bytes()
}

// ServeRead streams a slice of resource data to a bytestream.ByteStream_ReadServer
// according to the ReadOffset and ReadLimit in ReadRequest.
func ServeRead(req *bytestream.ReadRequest, resource []byte, chunkSize int, stream bytestream.ByteStream_ReadServer) error {
	offset := req.GetReadOffset()
	limit := req.GetReadLimit()
	if offset < 0 || offset > int64(len(resource)) {
		return errors.New("read_offset out of range")
	}
	if limit < 0 {
		return errors.New("negative read_limit")
	}
	end := int64(len(resource))
	if limit > 0 && offset+limit < end {
		end = offset + limit
	}
	if chunkSize <= 0 {
		chunkSize = 4
	}
	for pos := offset; pos < end; pos += int64(chunkSize) {
		next := pos + int64(chunkSize)
		if next > end {
			next = end
		}
		if err := stream.Send(&bytestream.ReadResponse{Data: resource[pos:next]}); err != nil {
			return err
		}
	}
	return nil
}

{
  "schemaVersion": 1,
  "goal": "verify google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer in pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c",
  "kind": "HOW",
  "packages": [
    "pkg:golang/google.golang.org/genproto/googleapis/bytestream@v0.0.0-20260311181403-84a4fc48630c"
  ],
  "symbols": [
    "google.golang.org/genproto/googleapis/bytestream.ByteStream_ReadServer"
  ]
}

package main

import (
	"bytes"
	"errors"
	"fmt"
	"os"

	sample "example.com/sample"
	"google.golang.org/genproto/googleapis/bytestream"
)

func main() {
	payload := []byte("0123456789abcdef")

	// 1. Verify ByteStream_ReadServer receives chunked ReadResponse messages respecting ReadOffset and ReadLimit.
	stream := &sample.MemoryReadServer{}
	var readSrv bytestream.ByteStream_ReadServer = stream

	req := &bytestream.ReadRequest{
		ResourceName: "blobs/resource-1",
		ReadOffset:   2,
		ReadLimit:    10,
	}
	if err := sample.ServeRead(req, payload, 4, readSrv); err != nil {
		fmt.Fprintf(os.Stderr, "unexpected ServeRead error: %v\n", err)
		os.Exit(1)
	}
	if len(stream.Responses) != 3 {
		fmt.Fprintf(os.Stderr, "expected 3 ReadResponse chunks, got %d\n", len(stream.Responses))
		os.Exit(1)
	}
	if got := stream.CollectedBytes(); !bytes.Equal(got, []byte("23456789ab")) {
		fmt.Fprintf(os.Stderr, "expected streamed bytes %q, got %q\n", "23456789ab", string(got))
		os.Exit(1)
	}

	// 2. Verify ByteStream_ReadServer.Send error propagation.
	expectedErr := errors.New("stream closed")
	failingStream := &sample.MemoryReadServer{SendErr: expectedErr}
	if err := sample.ServeRead(req, payload, 4, failingStream); !errors.Is(err, expectedErr) {
		fmt.Fprintf(os.Stderr, "expected error %v, got %v\n", expectedErr, err)
		os.Exit(1)
	}

	// 3. Verify UnimplementedByteStreamServer.Read accepts ByteStream_ReadServer and returns an error.
	var unimplemented bytestream.UnimplementedByteStreamServer
	if err := unimplemented.Read(req, readSrv); err == nil {
		fmt.Fprintln(os.Stderr, "expected UnimplementedByteStreamServer.Read to return an error")
		os.Exit(1)
	}
}