You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: aliasgen_test.go
    path of file: ./repos/google-cloud-go/internal/aliasgen
    
    the code of the file until where you have to start completion: // Copyright 2022 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.

//go:build go1.18
// +build go1.18

package aliasgen

import (
	"bytes"
	"flag"
	"os"
	"path/filepath"
	"testing"

	// needed for package loading/parsing to work properly
	"github.com/google/go-cmp/cmp"
	_ "google.golang.org/grpc"
)

var updateGoldens bool

func TestMain(m *testing.M) {
	flag.BoolVar(&updat
    
func TestGolden(t *testing.T) {
	srcDir := "testdata/fakepb"
	goldenDir := "testdata/golden"
	destDir := t.TempDir()

	if updateGoldens {
		os.RemoveAll(goldenDir)
		if err := Run(srcDir, filepath.Join(goldenDir, "fake")); err != nil {
			t.Fatalf("Run: %v", err)
		}
		t.Logf("Successfully updated golden files in %q", goldenDir)
		return
	}
	if err := Run(srcDir, destDir); err != nil {
		t.Fatalf("Run: %v", err)
	}

	// compare files excluding first header line with year
	gotBytes, err := os.ReadFile(filepath.Join(destDir, "alias.go"))
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	wantBytes, err := os.ReadFile(filepath.Join(goldenDir, "fake", "alias.go"))
	if err != nil {
		t.Fatalf("ReadFile: %v", err)
	}
	gotBytes = gotBytes[bytes.IndexRune(gotBytes, '\n')+1:]
	wantBytes = wantBytes[bytes.IndexRune(wantBytes, '\n')+1:]
	if diff := cmp.Diff(wantBytes, gotBytes); diff != "" {
		t.Errorf("bytes mismatch (-want +got):\n%s", diff)
	}

	if ok := bytes.Equal(gotBytes, wantBytes); !ok {
		t.Fatalf("got %s, want %s", gotBytes, wantBytes)
	}
}