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: json_test.go
    path of file: ./repos/cockroach/pkg/sql/sem/tree
    
    the code of the file until where you have to start completion: // Copyright 2022 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 tree_test

import (
	"context"
	"fmt"
	"math/rand"
	"testing"
	"time"

	"github.com/cockroachdb/cockroach/pkg/sql/randgen"
	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
	"github.com/cockroachdb/cockroach/pkg/sql/sessiondatapb"
	"github.com/cockroachdb/cockroach/pkg/sql/types"
	jsonb "github.com/cockroachdb/cockroach/pkg/
    
func testTypes(rng *rand.Rand) (typs []*types.T) {
	for _, typ := range randgen.SeedTypes {
		switch typ {
		case types.AnyTuple:
		// Ignore AnyTuple -- it's not very interesting; we'll generate test tuples below.
		case types.RegClass, types.RegNamespace, types.RegProc, types.RegProcedure, types.RegRole, types.RegType:
		// Ignore a bunch of pseudo-OID types (just want regular OID).
		case types.Geometry, types.Geography:
		// Ignore geometry/geography: these types are insanely inefficient;
		// AsJson(Geo) -> MarshalGeo -> go JSON bytes ->  ParseJSON -> Go native -> json.JSON
		// Benchmarking this generates too much noise.
		// TODO(yevgeniy): fix this.
		default:
			typs = append(typs, typ)
		}
	}

	// Add tuple types.
	var tupleTypes []*types.T
	makeTupleType := func() *types.T {
		contents := make([]*types.T, rng.Intn(6)) // Up to 6 fields
		for i := range contents {
			contents[i] = randgen.RandTypeFromSlice(rng, typs)
		}
		candidateTuple := types.MakeTuple(contents)
		// Ensure tuple type is unique.
		for _, t := range tupleTypes {
			if t.Equal(candidateTuple) {
				return nil
			}
		}
		tupleTypes = append(tupleTypes, candidateTuple)
		return candidateTuple
	}

	const numTupleTypes = 5
	for i := 0; i < numTupleTypes; i++ {
		var typ *types.T
		for typ == nil {
			typ = makeTupleType()
		}
		typs = append(typs, typ)
	}

	return typs
}