google.golang.org/appengine v1.2.0: IsOverQuota

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/appengine.IsOverQuota in pkg:golang/google.golang.org/appengine@v1.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/google.golang.org/appengine@v1.2.0
Demonstrate these symbols/APIs:
  - google.golang.org/appengine.IsOverQuota

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:a0927062c2d4cd6a9cfdf7aa3f68d83022c29dff9e6aa05ca39f3d32b6cfcc45","contract":["appengine.IsOverQuota(err) returns true when err is an *internal.CallError produced by an App Engine RPC response with RpcError_OVER_QUOTA (code 4)","appengine.IsOverQuota(err) returns false when err is an *internal.CallError with a non-over-quota RPC error code (code 1)","appengine.IsOverQuota(err) returns false for standard non-CallError errors and nil"],"goal":"verify google.golang.org/appengine.IsOverQuota in pkg:golang/google.golang.org/appengine@v1.2.0","kind":"HOW","packages":["pkg:golang/google.golang.org/appengine@v1.2.0"],"schemaVersion":1,"symbols":["google.golang.org/appengine.IsOverQuota"]},"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/appengine@v1.2.0"],"schemaVersion":1,"subject":"pkg:golang/google.golang.org/appengine@v1.2.0","symbols":["google.golang.org/appengine.IsOverQuota"],"verifierAdapter":"golang@1"}

module sample

go 1.26.0

require google.golang.org/appengine v1.2.0

require (
	github.com/golang/protobuf v1.2.0 // indirect
	golang.org/x/net v0.0.0-20180724234803-3673e40ba225 // indirect
	golang.org/x/sync v0.24.0 // indirect
)

github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=
github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
golang.org/x/net v0.0.0-20180724234803-3673e40ba225 h1:kNX+jCowfMYzvlSvJu5pQWEmyWFrBXJ3PBy10xKMXK8=
golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
golang.org/x/sync v0.24.0 h1:iqiDrGoDgyuvAKrhLQthUEzU/R378N78gXbBjxed7oA=
golang.org/x/sync v0.24.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
google.golang.org/appengine v1.2.0 h1:S0iUepdCWODXRvtE+gcRDd15L+k+k1AiHlMiMjefH24=
google.golang.org/appengine v1.2.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=

{
  "schemaVersion": 1,
  "goal": "verify google.golang.org/appengine.IsOverQuota in pkg:golang/google.golang.org/appengine@v1.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/google.golang.org/appengine@v1.2.0"
  ],
  "symbols": [
    "google.golang.org/appengine.IsOverQuota"
  ]
}

package main

import (
	"errors"
	"fmt"
	"net"
	"net/http"
	"net/http/httptest"
	"os"
	"sync/atomic"

	"google.golang.org/appengine"
)

type emptyProto struct{}

func (*emptyProto) Reset()         {}
func (*emptyProto) String() string { return "" }
func (*emptyProto) ProtoMessage()  {}

func encodeRpcErrorResponse(code byte, detail string) []byte {
	detailBytes := []byte(detail)
	rpcErrLen := 2 + 2 + len(detailBytes)
	out := make([]byte, 0, 2+rpcErrLen)
	// Response.rpc_error (field 5, wire type 2)
	out = append(out, 0x2a, byte(rpcErrLen))
	// RpcError.code (field 1, wire type 0)
	out = append(out, 0x08, code)
	// RpcError.detail (field 2, wire type 2)
	out = append(out, 0x12, byte(len(detailBytes)))
	out = append(out, detailBytes...)
	return out
}

func main() {
	var rpcCode uint32 = 4

	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		code := byte(atomic.LoadUint32(&rpcCode))
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write(encodeRpcErrorResponse(code, "quota limit reached"))
	}))
	defer srv.Close()

	host, port, err := net.SplitHostPort(srv.Listener.Addr().String())
	if err != nil {
		fmt.Fprintf(os.Stderr, "split host port failed: %v\n", err)
		os.Exit(1)
	}

	_ = os.Setenv("RUN_WITH_DEVAPPSERVER", "1")
	_ = os.Setenv("API_HOST", host)
	_ = os.Setenv("API_PORT", port)

	ctx := appengine.BackgroundContext()

	// 1. Over-quota CallError (RpcError_OVER_QUOTA == 4) must return true.
	overQuotaErr := appengine.APICall(ctx, "datastore_v3", "Get", &emptyProto{}, &emptyProto{})
	if overQuotaErr == nil {
		fmt.Fprintln(os.Stderr, "expected error from over-quota APICall, got nil")
		os.Exit(1)
	}
	if !appengine.IsOverQuota(overQuotaErr) {
		fmt.Fprintf(os.Stderr, "expected IsOverQuota(overQuotaErr) == true, got false (err=%v)\n", overQuotaErr)
		os.Exit(1)
	}

	// 2. Non-over-quota CallError (RpcError_CALL_NOT_FOUND == 1) must return false.
	atomic.StoreUint32(&rpcCode, 1)
	otherCallErr := appengine.APICall(ctx, "datastore_v3", "Get", &emptyProto{}, &emptyProto{})
	if otherCallErr == nil {
		fmt.Fprintln(os.Stderr, "expected error from non-over-quota APICall, got nil")
		os.Exit(1)
	}
	if appengine.IsOverQuota(otherCallErr) {
		fmt.Fprintf(os.Stderr, "expected IsOverQuota(otherCallErr) == false, got true (err=%v)\n", otherCallErr)
		os.Exit(1)
	}

	// 3. Generic non-CallError and nil must return false.
	if appengine.IsOverQuota(errors.New("plain error")) {
		fmt.Fprintln(os.Stderr, "expected IsOverQuota(plain error) == false, got true")
		os.Exit(1)
	}
	if appengine.IsOverQuota(nil) {
		fmt.Fprintln(os.Stderr, "expected IsOverQuota(nil) == false, got true")
		os.Exit(1)
	}
}