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: iterate_test.go
    path of file: ./repos/gitea/models/db
    
    the code of the file until where you have to start completion: // Copyright 2022 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package db_test

import (
	"context"
	"testing"

	"code.gitea.io/gitea/models/db"
	repo_model "code.gitea.io/gitea/models/repo"
	"code.gitea.io/gitea/models/unittest"

	"github.com/stretchr/testify/assert"
)

func TestIterate(t *testing.T) {
	assert.NoError(t, unittest.PrepareTestDatabase())
	xe := un
    
func TestIterate(t *testing.T) {
	assert.NoError(t, unittest.PrepareTestDatabase())
	xe := unittest.GetXORMEngine()
	assert.NoError(t, xe.Sync(&repo_model.RepoUnit{}))

	cnt, err := db.GetEngine(db.DefaultContext).Count(&repo_model.RepoUnit{})
	assert.NoError(t, err)

	var repoUnitCnt int
	err = db.Iterate(db.DefaultContext, nil, func(ctx context.Context, repo *repo_model.RepoUnit) error {
		repoUnitCnt++
		return nil
	})
	assert.NoError(t, err)
	assert.EqualValues(t, cnt, repoUnitCnt)

	err = db.Iterate(db.DefaultContext, nil, func(ctx context.Context, repoUnit *repo_model.RepoUnit) error {
		has, err := db.ExistByID[repo_model.RepoUnit](ctx, repoUnit.ID)
		if err != nil {
			return err
		}
		if !has {
			return db.ErrNotExist{Resource: "repo_unit", ID: repoUnit.ID}
		}
		assert.EqualValues(t, repoUnit.RepoID, repoUnit.RepoID)
		assert.EqualValues(t, repoUnit.CreatedUnix, repoUnit.CreatedUnix)
		return nil
	})
	assert.NoError(t, err)
}