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: dyndns_test.go
    path of file: ./repos/router7/internal/dyndns
    
    the code of the file until where you have to start completion: // Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the
    
func TestUpdate(t *testing.T) {
	ctx, canc := context.WithCancel(context.Background())
	defer canc()

	const zone = "zekjur.net"
	provider := &testProvider{
		getRecords: func(ctx context.Context, zone string) ([]libdns.Record, error) {
			return []libdns.Record{
				{
					ID:    "rec1",
					Name:  "dyndns.zekjur.net",
					Type:  "A",
					TTL:   5 * time.Minute,
					Value: "127.0.0.3",
				},

				{
					ID:    "rec1",
					Name:  "unrelated.zekjur.net",
					Type:  "A",
					TTL:   5 * time.Minute,
					Value: "127.0.0.42",
				},
			}, nil
		},
		setRecords: func(ctx context.Context, zone string, recs []libdns.Record) ([]libdns.Record, error) {
			log.Printf("setRecords(zone=%q): %+v", zone, recs)
			// Don't care about return records?
			return nil, nil
		},
	}
	update := libdns.Record{
		Name:  "dyndns.zekjur.net",
		Type:  "A",
		Value: "127.0.0.4",
		TTL:   5 * time.Minute,
	}
	if err := Update(ctx, zone, update, provider); err != nil {
		t.Fatalf("Update = %v", err)
	}

	// TODO: add a test to verify setRecords is not called
	// when no updates are necessary.
}