chore: add release init cmd skeleton (#1742)

Updates #1008

Author: JoeWang1127

internal/librarian/init.go

@@ -0,0 +1,68 @@
+// Copyright 2025 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 librarian
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/googleapis/librarian/internal/cli"
+	"github.com/googleapis/librarian/internal/config"
+)
+
+// cmdInit is the command for the `release init` subcommand.
+var cmdInit = &cli.Command{
+	Short:     "release init initiates a release by creating a release pull request.",
+	UsageLine: "librarian release init [arguments]",
+	Long: `The release init command is the primary entry point for initiating a release.
+It orchestrates the process of parsing commits, determining new versions, generating
+a changelog, and creating a release pull request.`,
+	Run: func(ctx context.Context, cfg *config.Config) error {
+		runner, err := newInitRunner(cfg)
+		if err != nil {
+			return err
+		}
+		return runner.run(ctx)
+	},
+}
+
+func init() {
+	cmdInit.Init()
+	fs := cmdInit.Flags
+	cfg := cmdInit.Config
+
+	addFlagRepo(fs, cfg)
+	addFlagImage(fs, cfg)
+	addFlagLibrary(fs, cfg)
+}
+
+type initRunner struct {
+	cfg *config.Config
+}
+
+func newInitRunner(cfg *config.Config) (*initRunner, error) {
+	if ok, err := cfg.IsValid(); !ok || err != nil {
+		return nil, fmt.Errorf("invalid config: %+v", cfg)
+	}
+
+	return &initRunner{
+		cfg: cfg,
+	}, nil
+}
+
+func (r *initRunner) run(ctx context.Context) error {
+	return errors.New("not implemented")
+}

internal/librarian/init_test.go

@@ -0,0 +1,99 @@
+// Copyright 2025 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 librarian
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/googleapis/librarian/internal/config"
+)
+
+func TestNewInitRunner(t *testing.T) {
+	testcases := []struct {
+		name       string
+		cfg        *config.Config
+		wantErr    bool
+		wantErrMsg string
+	}{
+		{
+			name: "valid config",
+			cfg:  &config.Config{},
+		},
+		{
+			name: "invalid config",
+			cfg: &config.Config{
+				Push: true,
+			},
+			wantErr:    true,
+			wantErrMsg: "invalid config",
+		},
+	}
+	for _, test := range testcases {
+		t.Run(test.name, func(t *testing.T) {
+			_, err := newInitRunner(test.cfg)
+			if test.wantErr {
+				if err == nil {
+					t.Error("newInitRunner() should return error")
+				}
+
+				if !strings.Contains(err.Error(), test.wantErrMsg) {
+					t.Errorf("want error message: %q, got %q", test.wantErrMsg, err.Error())
+				}
+
+				return
+			}
+			if err != nil {
+				t.Errorf("newInitRunner() got nil runner, want non-nil")
+			}
+		})
+	}
+}
+
+func TestInitRun(t *testing.T) {
+	testcases := []struct {
+		name       string
+		runner     *initRunner
+		wantErr    bool
+		wantErrMsg string
+	}{
+		{
+			name:       "invalid",
+			runner:     &initRunner{},
+			wantErr:    true,
+			wantErrMsg: "not implemented",
+		},
+	}
+	for _, test := range testcases {
+		t.Run(test.name, func(t *testing.T) {
+			err := test.runner.run(context.Background())
+			if test.wantErr {
+				if err == nil {
+					t.Error("run() should return error")
+				}
+
+				if !strings.Contains(err.Error(), test.wantErrMsg) {
+					t.Errorf("want error message: %q, got %q", test.wantErrMsg, err.Error())
+				}
+
+				return
+			}
+			if err != nil {
+				t.Errorf("run() got nil runner, want non-nil")
+			}
+		})
+	}
+}

internal/librarian/release.go

@@ -28,6 +28,7 @@ var cmdRelease = &cli.Command{
 func init() {
 	cmdRelease.Init()
 	CmdLibrarian.Commands = append(CmdLibrarian.Commands,
+		cmdInit,
 		cmdTagAndRelease,
 	)
 }