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: revoke_test.go
    path of file: ./repos/tidb/pkg/executor
    
    the code of the file until where you have to start completion: // Copyright 2017 PingCAP, Inc.
//
// 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.

package executor_test

import (
	"fmt"
	"strings"
	"testing"

	"github.com/pingcap/tidb/pkg/executor"
	"github.com/pingcap/tidb/pkg/parser/mysql"
	"github.com/pingcap/tidb/pkg/testkit"
	"github.com/stretchr/testify/require"
)

func TestRevokeGlobal(t *testing.T) {
	store := testkit.CreateMockStore(t)
	tk := testkit.NewTestKit(t, store)

	_, err := tk.Exec(`REVOKE ALL PRIVILEGES ON *.* FROM 'nonexistuser'@'host'`)
	require.Error(t, err)

	// Create a new user.
	createUserSQL := `CREATE USER 'testGlobalRevoke'@'localhost' IDENTIFIED BY '123';`
	tk.MustExec(createUserSQL)
	grantPrivSQL := `GRANT ALL PRIVILEGES ON *.* to 'testGlobalRevoke'@'localhost';`
	tk.MustExec(grantPrivSQL)

	// Make sure all the global privs for new user is "Y".
	for _, v := range mysql.AllDBPrivs {
		sql := fmt.Sprintf(`SELECT %s FROM mysql.User WHERE User="testGlobalRevoke" and host="localhost";`, mysql.Priv2UserCol[v])
		r := tk.MustQuery(sql)
		r.Check(testkit.Rows("Y"))
	}

	// Revoke each priv from the user.
	for _, v := range mysql.AllGlobalPrivs {
		sql := fmt.Sprintf("REVOKE %s ON *.* FROM 'testGlobalRevoke'@'localhost';", mysql.Priv2Str[v])
		tk.MustExec(sql)
		sql = fmt.Sprintf(`SELECT %s FROM mysql.User WHERE User="testGlobalRevoke" and host="localhost"`, mysql.Priv2UserCol[v])
		tk.MustQuery(sql).Check(testkit.Rows
    
func TestRevokeColumnScope(t *testing.T) {
	store := testkit.CreateMockStore(t)
	tk := testkit.NewTestKit(t, store)
	// Create a new user.
	tk.MustExec(`CREATE USER 'testColRevoke'@'localhost' IDENTIFIED BY '123';`)
	tk.MustExec(`CREATE TABLE test.test3(c1 int, c2 int);`)
	tk.MustQuery(`SELECT * FROM mysql.Columns_priv WHERE User="testColRevoke" and host="localhost" and db="test" and Table_name="test3" and Column_name="c2"`).Check(testkit.Rows())

	// Grant and Revoke each priv on the user.
	for _, v := range mysql.AllColumnPrivs {
		grantSQL := fmt.Sprintf("GRANT %s(c1) ON test.test3 TO 'testColRevoke'@'localhost';", mysql.Priv2Str[v])
		revokeSQL := fmt.Sprintf("REVOKE %s(c1) ON test.test3 FROM 'testColRevoke'@'localhost';", mysql.Priv2Str[v])
		checkSQL := `SELECT Column_priv FROM mysql.Columns_priv WHERE User="testColRevoke" and host="localhost" and db="test" and Table_name="test3" and Column_name="c1"`

		tk.MustExec(grantSQL)
		rows := tk.MustQuery(checkSQL).Rows()
		require.Len(t, rows, 1)
		row := rows[0]
		require.Len(t, row, 1)
		p := fmt.Sprintf("%v", row[0])
		require.Greater(t, strings.Index(p, mysql.Priv2SetStr[v]), -1)

		tk.MustExec(revokeSQL)
		//delete row when last prv , updated by issue #38421
		rows = tk.MustQuery(checkSQL).Rows()
		require.Len(t, rows, 0)
	}

	// Create a new user.
	tk.MustExec("CREATE USER 'testCol1Revoke'@'localhost' IDENTIFIED BY '123';")
	tk.MustExec("USE test;")
	// Grant all column scope privs.
	tk.MustExec("GRANT ALL(c2) ON test3 TO 'testCol1Revoke'@'localhost';")
	// Make sure all the column privs for granted user are in the Column_priv set.
	for _, v := range mysql.AllColumnPrivs {
		rows := tk.MustQuery(`SELECT Column_priv FROM mysql.Columns_priv WHERE User="testCol1Revoke" and host="localhost" and db="test" and Table_name="test3" and Column_name="c2";`).Rows()
		require.Len(t, rows, 1)
		row := rows[0]
		require.Len(t, row, 1)
		p := fmt.Sprintf("%v", row[0])
		require.Greater(t, strings.Index(p, mysql.Priv2SetStr[v]), -1)
	}
	tk.MustExec("REVOKE ALL(c2) ON test3 FROM 'testCol1Revoke'@'localhost'")
	//delete row when last prv , updated by issue #38421
	rows := tk.MustQuery(`SELECT Column_priv FROM mysql.Columns_priv WHERE User="testCol1Revoke" and host="localhost" and db="test" and Table_name="test3"`).Rows()
	require.Len(t, rows, 0)
}