impl: devtools/cmd/generate,testdata: add command to run protoc-gen

generator/README.md

@@ -6,6 +6,12 @@ A tool for generating client libraries.
 
 Run the following command from the generator directory:
 
+```bash
+go run ./devtools/cmd/generate -language=rust
+```
+
+Alternatively, you can run the protoc command directly:
+
 ```bash
 go install github.com/googleapis/google-cloud-rust/generator/cmd/protoc-gen-gclient
 protoc -I cmd/protoc-gen-gclient/testdata/smprotos \

generator/devtools/cmd/generate/main.go

@@ -0,0 +1,72 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"log/slog"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+var (
+	input    = flag.String("input", "testdata/google/cloud/secretmanager/v1/", "path to protos to generate from")
+	output   = flag.String("out", "output", "the path to the output directory")
+	language = flag.String("language", "", "the generated language")
+	testdata = flag.String("testdata", "testdata/", "path to testdata directory")
+)
+
+func main() {
+	flag.Parse()
+	if *language == "" {
+		log.Fatalf("language must be provided")
+	}
+	if err := run(*language, *testdata, *input, *output); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(language, testdata, input, output string) error {
+	var files []string
+	err := filepath.Walk(input, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if filepath.Ext(path) == ".proto" {
+			files = append(files, path)
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	args := []string{
+		"-I", testdata,
+		fmt.Sprintf("--gclient_out=%s", output),
+		fmt.Sprintf("--gclient_opt=language=%s", language),
+	}
+	args = append(args, files...)
+
+	cmd := exec.Command("protoc", args...)
+	slog.Info(cmd.String())
+
+	cmd.Stdout = os.Stdout // or any other io.Writer
+	cmd.Stderr = os.Stderr // or any other io.Writer
+	return cmd.Run()
+}

generator/internal/genclient/genclient.go

@@ -122,10 +122,7 @@ func Generate(req *GenerateRequest) (*Output, error) {
 			return err
 		}
 		fn := filepath.Join(req.outDir(), filepath.Dir(strings.TrimPrefix(path, root)), strings.TrimSuffix(d.Name(), ".mustache"))
-		if err := os.WriteFile(fn, []byte(s), os.ModePerm); err != nil {
-			return err
-		}
-		return nil
+		return os.WriteFile(fn, []byte(s), os.ModePerm)
 	})
 	if err != nil {
 		slog.Error("error walking templates", "err", err.Error())

generator/testdata/google/api/annotations.proto

@@ -0,0 +1,31 @@
+// Copyright 2015 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+import "google/api/http.proto";
+import "google/protobuf/descriptor.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "AnnotationsProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+extend google.protobuf.MethodOptions {
+  // See `HttpRule`.
+  HttpRule http = 72295728;
+}