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: block.rs
    path of file: ./repos/grin/core/tests
    
    the code of the file until where you have to start completion: // Copyright 2021 The Grin Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the Lic
    
fn compact_block_single_tx_serialized_size() {
	test_setup();
	let keychain = ExtKeychain::from_random_seed(false).unwrap();
	let builder = ProofBuilder::new(&keychain);
	let tx1 = tx1i2o();
	let prev = BlockHeader::default();
	let key_id = ExtKeychain::derive_key_id(1, 1, 0, 0, 0);
	let b = new_block(&[tx1], &keychain, &builder, &prev, &key_id);
	let cb: CompactBlock = b.into();
	let mut vec = Vec::new();
	ser::serialize_default(&mut vec, &cb).expect("serialization failed");
	assert_eq!(vec.len(), 1_110);
}