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: allocator_test.go
    path of file: ./repos/cockroach/pkg/kv/kvserver/allocator/allocatorimpl
    
    the code of the file until where you have to start completion: // Copyright 2014 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 allocatorimpl

import (
	"context"
	"fmt"
	"math"
	"os"
	"reflect"
	"sort"
	"strconv"
	"sync"
	"testing"
	"time"

	"github.com/cockroachdb/cockroach/pkg/gossip"
	"github.com/cockroachdb/cockroach/pkg/keys"
	"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/load"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/storepool"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/constraint"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/liveness"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/liveness/livenesspb"
	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/replicastats"
	"github.com/cockroachdb/cockroach/pkg/roachpb"
	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
	"github.com/cockroachdb/cockroach/pkg/testutils"
	"github.com/cockroachdb/cockroach/pkg/testutils/gossiputil"
	"github.com/cockroachdb/cockroach/pkg/util"
	"github.com/cockroachdb/cockroach/pkg/util/hlc"
	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
	"github.com/cockroachdb/cockroach/pkg/util/log"
	"github.com/cockroachdb/cockroach/pkg/util/metric"
	"github.com/cockroachdb/cockroach/pkg/util/stop"
	"github.com/cockroachdb/cockroach/pkg/util/tracing"
	"g
    
func TestAllocatorAllocateTargetLocality(t *testing.T) {
	defer leaktest.AfterTest(t)()
	defer log.Scope(t).Close(t)

	ctx := context.Background()
	stopper, g, sp, a, _ := CreateTestAllocator(ctx, 10, false /* deterministic */)
	defer stopper.Stop(ctx)
	sg := gossiputil.NewStoreGossiper(g)
	sg.GossipStores(multiDiversityDCStores, t)

	// Given a set of existing replicas for a range, rank which of the remaining
	// stores from multiDiversityDCStores would be the best addition to the range
	// purely on the basis of locality diversity.
	testCases := []struct {
		existing []roachpb.StoreID
		expected []roachpb.StoreID
	}{
		{
			[]roachpb.StoreID{1, 2, 3},
			[]roachpb.StoreID{5, 6, 7, 8},
		},
		{
			[]roachpb.StoreID{1, 3, 4},
			[]roachpb.StoreID{5, 6, 7, 8},
		},
		{
			[]roachpb.StoreID{3, 4, 5},
			[]roachpb.StoreID{1, 2, 7, 8},
		},
		{
			[]roachpb.StoreID{1, 7, 8},
			[]roachpb.StoreID{3, 4, 5, 6},
		},
		{
			[]roachpb.StoreID{5, 7, 8},
			[]roachpb.StoreID{1, 2, 3, 4},
		},
		{
			[]roachpb.StoreID{1, 3, 5},
			[]roachpb.StoreID{7, 8},
		},
		{
			[]roachpb.StoreID{1, 3, 7},
			[]roachpb.StoreID{5, 6},
		},
		{
			[]roachpb.StoreID{1, 5, 7},
			[]roachpb.StoreID{3, 4},
		},
		{
			[]roachpb.StoreID{3, 5, 7},
			[]roachpb.StoreID{1, 2},
		},
	}

	for _, c := range testCases {
		existingRepls := make([]roachpb.ReplicaDescriptor, len(c.existing))
		for i, storeID := range c.existing {
			existingRepls[i] = roachpb.ReplicaDescriptor{
				NodeID:  roachpb.NodeID(storeID),
				StoreID: storeID,
			}
		}
		targetStore, details, err := a.AllocateVoter(ctx, sp, emptySpanConfig(), existingRepls, nil, nil, Dead)
		if err != nil {
			t.Fatal(err)
		}
		var found bool
		for _, storeID := range c.expected {
			if targetStore.StoreID == storeID {
				found = true
				break
			}
		}
		if !found {
			t.Errorf("expected AllocateVoter(%v) in %v, but got %d; details: %s", c.existing, c.expected, targetStore.StoreID, details)
		}
	}
}