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: mock_test.go
    path of file: ./repos/gitkube/vendor/cloud.google.com/go/pubsub/apiv1
    
    the code of the file until where you have to start completion: // Copyright 2018 Google LLC
//
// 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 ap
    
func TestSubscriberModifyAckDeadlineError(t *testing.T) {
	errCode := codes.PermissionDenied
	mockSubscriber.err = gstatus.Error(errCode, "test error")

	var formattedSubscription string = fmt.Sprintf("projects/%s/subscriptions/%s", "[PROJECT]", "[SUBSCRIPTION]")
	var ackIds []string = nil
	var ackDeadlineSeconds int32 = 2135351438
	var request = &pubsubpb.ModifyAckDeadlineRequest{
		Subscription:       formattedSubscription,
		AckIds:             ackIds,
		AckDeadlineSeconds: ackDeadlineSeconds,
	}

	c, err := NewSubscriberClient(context.Background(), clientOpt)
	if err != nil {
		t.Fatal(err)
	}

	err = c.ModifyAckDeadline(context.Background(), request)

	if st, ok := gstatus.FromError(err); !ok {
		t.Errorf("got error %v, expected grpc error", err)
	} else if c := st.Code(); c != errCode {
		t.Errorf("got error code %q, want %q", c, errCode)
	}
}