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: index_constraints_test.go
    path of file: ./repos/cockroach/pkg/sql/opt/idxconstraint
    
    the code of the file until where you have to start completion: // Copyright 2017 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

package idxconstraint_test

import (
	"bytes"
	"context"
	"fmt"
	"strings"
	"testing"

	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
	"github.com/cockroachdb/cockroach/pkg/sql/opt"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/exec/execbuilder"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/idxconstraint"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/memo"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/norm"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/optbuilder"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/partition"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/props"
	"github.com/cockroachdb/cockroach/pkg/sql/opt/testutils"
	"github.com/cockroachdb/cockroach/pkg/sql/parser"
	"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
	tu "github.com/cockroachdb/cockroach/pkg/testutils/datapathutils"
	"g
    
func BenchmarkIndexConstraints(b *testing.B) {
	type testCase struct {
		name, vars, indexInfo, expr string
	}
	testCases := []testCase{
		{
			name:      "point-lookup",
			vars:      "a int",
			indexInfo: "a",
			expr:      "a = 1",
		},
		{
			name:      "no-constraints",
			vars:      "a int, b int",
			indexInfo: "b",
			expr:      "a = 1",
		},
		{
			name:      "range",
			vars:      "a int",
			indexInfo: "a",
			expr:      "a >= 1 AND a <= 10",
		},
		{
			name:      "range-2d",
			vars:      "a int, b int",
			indexInfo: "a, b",
			expr:      "a >= 1 AND a <= 10 AND b >= 1 AND b <= 10",
		},
		{
			name:      "many-columns",
			vars:      "a int, b int, c int, d int, e int",
			indexInfo: "a, b, c, d, e",
			expr:      "a = 1 AND b >= 2 AND b <= 4 AND (c, d, e) IN ((3, 4, 5), (6, 7, 8))",
		},
	}
	// Generate a few testcases with many columns with single value constraint.
	// This characterizes scaling w.r.t the number of columns.
	for _, n := range []int{10, 100} {
		var tc testCase
		tc.name = fmt.Sprintf("single-jumbo-span-%d", n)
		for i := 1; i <= n; i++ {
			if i > 1 {
				tc.vars += ", "
				tc.indexInfo += ", "
				tc.expr += " AND "
			}
			tc.vars += fmt.Sprintf("x%d int", i)
			tc.indexInfo += fmt.Sprintf("x%d", i)
			tc.expr += fmt.Sprintf("x%d=%d", i, i)
		}
		testCases = append(testCases, tc)
	}

	semaCtx := tree.MakeSemaContext()
	evalCtx := eval.MakeTestingEvalContext(cluster.MakeTestingClusterSettings())

	for _, tc := range testCases {
		b.Run(tc.name, func(b *testing.B) {
			var f norm.Factory
			f.Init(context.Background(), &evalCtx, nil /* catalog */)
			md := f.Metadata()
			var sv testutils.ScalarVars
			err := sv.Init(md, strings.Split(tc.vars, ", "))
			if err != nil {
				b.Fatal(err)
			}
			indexCols := parseIndexColumns(b, md, strings.Split(tc.indexInfo, ", "))

			filters, err := buildFilters(tc.expr, &semaCtx, &evalCtx, &f)
			if err != nil {
				b.Fatal(err)
			}

			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				var ic idxconstraint.Instance
				ic.Init(
					filters, nil /* optionalFilters */, indexCols, sv.NotNullCols(),
					nil /* computedCols */, opt.ColSet{}, /* colsInComputedColsExpressions */
					true, /* consolidate */
					&evalCtx, &f, partition.PrefixSorter{},
					func() {}, /* checkCancellation */
				)
				_ = ic.Constraint()
				_ = ic.RemainingFilters()
			}
		})
	}
}