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: corrector_test.go
    path of file: ./repos/vald/pkg/index/job/correction/service
    
    the code of the file until where you have to start completion: // Copyright (C) 2019-2024 vdaas.org vald team <vald@vdaas.org>
//
// 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
//
//	https://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 service

import (
	"context"
	"testing"

	tmock "github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"
	"github.com/vdaas/vald/apis/grpc/v1/payload"
	"github.com/vdaas/vald/internal/errors"
	"github.com/vdaas/vald/internal/net/grpc"
	"github.com/vdaas/vald/internal/test/mock"
)

type mockDiscovererClient struct {
	client mock.ClientInternal
}

func (*mockDiscovererClient) Start(context.Context) (<-chan error, error) {
	return nil, nil
}

func (*mockDiscovererClient) GetAddrs(context.Context) []string {
	return nil
}

func (m *mockDiscovererClient) GetClient() grpc.Client {
	return &m.client
}

func (m *mockDiscovererClient) GetReadClient() grpc.Client {
	return &m.client
}

func Test_correct_correctTimestamp(t *testing.T) {
	t.Parallel()

	// This mock just returns nil and record args inside
	m := mockDiscovererClient{}
	m.client
    
func Test_correct_correctReplica(t *testing.T) {
	t.Parallel()

	// This mock just returns nil and record args inside
	m := mockDiscovererClient{}
	m.client.On("Do", tmock.Anything, tmock.Anything, tmock.Anything).Return(nil, nil)

	type args struct {
		indexReplica   int
		target         *vectorReplica
		found          []*vectorReplica
		availableAddrs []string
	}

	type addrMethod struct {
		addr   string
		method string
	}

	type want struct {
		addrMethods []addrMethod
		err         error
	}

	type test struct {
		name string
		args args
		want want
	}

	tests := []test{
		{
			name: "nothing happens when replica number sutisfies",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found: []*vectorReplica{
					{
						addr: "found",
						vec: &payload.Object_Vector{
							Id: "found",
						},
					},
				},
				availableAddrs: []string{},
			},
			want: want{
				addrMethods: nil,
				err:         nil,
			},
		},
		{
			name: "insert replica when replica number is not enough",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found:          []*vectorReplica{},
				availableAddrs: []string{"available"},
			},
			want: want{
				addrMethods: []addrMethod{
					{
						addr:   "available",
						method: insertMethod,
					},
				},
				err: nil,
			},
		},
		{
			name: "insert replica to the agent with most memory available",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found: []*vectorReplica{},
				// this is supposed to be sorted by memory usage with descending order
				availableAddrs: []string{"most memory used", "second memory used"},
			},
			want: want{
				addrMethods: []addrMethod{
					{
						addr:   "second memory used",
						method: insertMethod,
					},
				},
				err: nil,
			},
		},
		{
			name: "delete replica from myself when replica number is too much by one",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found: []*vectorReplica{
					{
						addr: "found1",
					},
					{
						addr: "found2",
					},
				},
				availableAddrs: []string{},
			},
			want: want{
				addrMethods: []addrMethod{
					{
						addr:   "target",
						method: deleteMethod,
					},
				},
				err: nil,
			},
		},
		{
			name: "delete replica from myself and most memory used agent when replica number is too much by more than one",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found: []*vectorReplica{
					{
						addr: "found1",
					},
					{
						addr: "found2",
					},
					{
						addr: "found3",
					},
				},
				availableAddrs: []string{},
			},
			want: want{
				addrMethods: []addrMethod{
					{
						addr:   "target",
						method: deleteMethod,
					},
					{
						addr:   "found1",
						method: deleteMethod,
					},
				},
				err: nil,
			},
		},
		{
			name: "return ErrNoAvailableAgentToInsert when availableAddrs is empty when insertion required",
			args: args{
				indexReplica: 2,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found:          []*vectorReplica{},
				availableAddrs: []string{},
			},
			want: want{
				addrMethods: nil,
				err:         errors.ErrNoAvailableAgentToInsert,
			},
		},
		{
			name: "return ErrFailedToCorrectReplicaNum when there is not enough number of availableAddrs",
			args: args{
				indexReplica: 3,
				target: &vectorReplica{
					addr: "target",
					vec: &payload.Object_Vector{
						Id: "target",
					},
				},
				found:          []*vectorReplica{},
				availableAddrs: []string{"available"},
			},
			want: want{
				addrMethods: nil,
				err:         errors.ErrFailedToCorrectReplicaNum,
			},
		},
	}

	for _, tc := range tests {
		test := tc
		c := &correct{
			discoverer:   &m,
			indexReplica: test.args.indexReplica,
		}

		// agentAddrs = availableAddrs + target.addr + found.addr
		// skipcq: CRT-D0001
		c.agentAddrs = append(test.args.availableAddrs, test.args.target.addr)
		for _, found := range test.args.found {
			c.agentAddrs = append(c.agentAddrs, found.addr)
		}

		t.Run(test.name, func(tt *testing.T) {
			tt.Parallel()
			err := c.correctReplica(context.Background(), test.args.target, test.args.found)
			if test.want.err != nil {
				require.ErrorIs(t, test.want.err, err)
			}

			for _, am := range test.want.addrMethods {
				// check if the agents which need to be corrected are called with the required method
				// checking calling parameter, like timestamp, is impossible because its inside of the function arg
				m.client.AssertCalled(tt, "Do", tmock.MatchedBy(func(ctx context.Context) bool {
					method := ctx.Value(grpc.GRPCMethodContextKey)
					val, ok := method.(string)
					if !ok {
						return false
					}
					return val == am.method
				}), am.addr, tmock.Anything)
			}
		})
	}
}