Fragile Address Limit Implementation in Tests

[mpguerra]

In the following code snippet from zebra-network’s AddressBook implementation, the helper function adds a list of peer addresses to the address book. However, it first takes addr_limit elements from the list and then deduplicates it, as such if there are repeated elements in the truncated list, the resulting address book will be smaller than the required limit. It is more robust to deduplicate the list and then take addr_limit elements from it. As this function is only used in tests, it is left as a note:

zebra/zebra-network/src/address_book.rs

Lines 143 to 188 in 5a88fe7

	/// Construct an [`AddressBook`] with the given `local_listener`, `network`,
	/// `addr_limit`, [`tracing::Span`], and addresses.
	///
	/// `addr_limit` is enforced by this method, and by [`AddressBook::update`].
	///
	/// If there are multiple [`MetaAddr`]s with the same address,
	/// an arbitrary address is inserted into the address book,
	/// and the rest are dropped.
	///
	/// This constructor can be used to break address book invariants,
	/// so it should only be used in tests.
	#[cfg(any(test, feature = "proptest-impl"))]
	pub fn new_with_addrs(
	local_listener: SocketAddr,
	network: Network,
	addr_limit: usize,
	span: Span,
	addrs: impl IntoIterator<Item = MetaAddr>,
	) -> AddressBook {
	let constructor_span = span.clone();
	let _guard = constructor_span.enter();
	let instant_now = Instant::now();
	let chrono_now = Utc::now();
	let mut new_book = AddressBook::new(local_listener, network, span);
	new_book.addr_limit = addr_limit;
	let addrs = addrs
	.into_iter()
	.map(|mut meta_addr| {
	meta_addr.addr = canonical_socket_addr(meta_addr.addr);
	meta_addr
	})
	.filter(|meta_addr| meta_addr.address_is_valid_for_outbound(network))
	.take(addr_limit)
	.map(|meta_addr| (meta_addr.addr, meta_addr));
	for (socket_addr, meta_addr) in addrs {
	// overwrite any duplicate addresses
	new_book.by_addr.insert(socket_addr, meta_addr);
	}
	new_book.update_metrics(instant_now, chrono_now);
	new_book
	}

[mpguerra]

Hey team! Please add your planning poker estimate with Zenhub @arya2 @conradoplg @dconnolly @oxarbitrage @teor2345 @upbqdn