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: tx_test.go
    path of file: ./repos/go-zero/core/stores/sqlx
    
    the code of the file until where you have to start completion: package sqlx

import (
	"context"
	"database/sql"
	"errors"
	"testing"

	"github.com/DATA-DOG/go-sqlmock"
	"github.com/stretchr/testify/assert"
	"github.com/zeromicro/go-zero/core/breaker"
	"github.com/zeromicro/go-zero/core/stores/dbtest"
)

const (
	mockCommit   = 1
	mockRollback = 2
)

type mockTx
    
func TestTxRollback(t *testing.T) {
	dbtest.RunTest(t, func(db *sql.DB, mock sqlmock.Sqlmock) {
		mock.ExpectBegin()
		mock.ExpectExec("any").WillReturnResult(sqlmock.NewResult(2, 3))
		mock.ExpectQuery("foo").WillReturnError(errors.New("foo"))
		mock.ExpectRollback()

		conn := NewSqlConnFromDB(db)
		err := conn.Transact(func(session Session) error {
			c := NewSqlConnFromSession(session)
			_, err := c.Exec("any")
			assert.NoError(t, err)

			var val string
			return c.QueryRow(&val, "foo")
		})
		assert.Error(t, err)
	})

	dbtest.RunTest(t, func(db *sql.DB, mock sqlmock.Sqlmock) {
		mock.ExpectBegin()
		mock.ExpectExec("any").WillReturnError(errors.New("foo"))
		mock.ExpectRollback()

		conn := NewSqlConnFromDB(db)
		err := conn.Transact(func(session Session) error {
			c := NewSqlConnFromSession(session)
			if _, err := c.Exec("any"); err != nil {
				return err
			}

			var val string
			assert.NoError(t, c.QueryRow(&val, "foo"))
			return nil
		})
		assert.Error(t, err)
	})

	dbtest.RunTest(t, func(db *sql.DB, mock sqlmock.Sqlmock) {
		mock.ExpectBegin()
		mock.ExpectExec("any").WillReturnResult(sqlmock.NewResult(2, 3))
		mock.ExpectQuery("foo").WillReturnRows(sqlmock.NewRows([]string{"col"}).AddRow("bar"))
		mock.ExpectCommit()

		conn := NewSqlConnFromDB(db)
		err := conn.Transact(func(session Session) error {
			c := NewSqlConnFromSession(session)
			_, err := c.Exec("any")
			assert.NoError(t, err)

			var val string
			assert.NoError(t, c.QueryRow(&val, "foo"))
			assert.Equal(t, "bar", val)
			return nil
		})
		assert.NoError(t, err)
	})
}