Derive Arbitrary impls for a bunch of chain and network types (#2179)

Enable proptests for internal and external network protocol messages,
using times with the correct protocol-specific ranges. (4 or 8 bytes.)

zebra-chain/src/block/arbitrary.rs

@@ -3,11 +3,11 @@ use proptest::{
     prelude::*,
 };
 
-use chrono::{TimeZone, Utc};
 use std::sync::Arc;
 
 use crate::{
     parameters::{Network, NetworkUpgrade},
+    serialization,
     work::{difficulty::CompactDifficulty, equihash},
 };
 
@@ -186,8 +186,7 @@ impl Arbitrary for Header {
             any::<Hash>(),
             any::<merkle::Root>(),
             any::<[u8; 32]>(),
-            // time is interpreted as u32 in the spec, but rust timestamps are i64
+            serialization::arbitrary::datetime_u32(),
-            (0i64..(u32::MAX as i64)),
             any::<CompactDifficulty>(),
             any::<[u8; 32]>(),
             any::<equihash::Solution>(),
@@ -198,7 +197,7 @@ impl Arbitrary for Header {
                     previous_block_hash,
                     merkle_root,
                     commitment_bytes,
-                    timestamp,
+                    time,
                     difficulty_threshold,
                     nonce,
                     solution,
@@ -207,7 +206,7 @@ impl Arbitrary for Header {
                     previous_block_hash,
                     merkle_root,
                     commitment_bytes,
-                    time: Utc.timestamp(timestamp, 0),
+                    time,
                     difficulty_threshold,
                     nonce,
                     solution,

zebra-chain/src/block/header.rs

@@ -10,6 +10,9 @@ use crate::{
 
 use super::{merkle, Hash, Height};
 
+#[cfg(any(test, feature = "proptest-impl"))]
+use proptest_derive::Arbitrary;
+
 /// A block header, containing metadata about a block.
 ///
 /// How are blocks chained together? They are chained together via the
@@ -121,6 +124,7 @@ impl Header {
 ///
 /// This structure is used in the Bitcoin network protocol.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct CountedHeader {
     pub header: Header,
     pub transaction_count: usize,

zebra-chain/src/serialization.rs

@@ -17,6 +17,9 @@ pub(crate) mod serde_helpers;
 
 pub mod sha256d;
 
+#[cfg(any(test, feature = "proptest-impl"))]
+pub mod arbitrary;
+
 pub use constraint::AtLeastOne;
 pub use error::SerializationError;
 pub use read_zcash::ReadZcashExt;

zebra-chain/src/serialization/arbitrary.rs

@@ -0,0 +1,33 @@
+use chrono::{TimeZone, Utc, MAX_DATETIME, MIN_DATETIME};
+use proptest::{arbitrary::any, prelude::*};
+
+/// Returns a strategy that produces an arbitrary [`chrono::DateTime<Utc>`],
+/// based on the full valid range of the type.
+///
+/// Both the seconds and nanoseconds values are randomised. But leap nanoseconds
+/// are never present.
+/// https://docs.rs/chrono/0.4.19/chrono/struct.DateTime.html#method.timestamp_subsec_nanos
+///
+/// Zebra uses these times internally, via [`Utc::now`].
+///
+/// Some parts of the Zcash network protocol ([`Version`] messages) also use times
+/// with an 8-byte seconds value. Unlike this function, they have zero
+/// nanoseconds values.
+pub fn datetime_full() -> impl Strategy<Value = chrono::DateTime<Utc>> {
+    (
+        MIN_DATETIME.timestamp()..=MAX_DATETIME.timestamp(),
+        0..1_000_000_000_u32,
+    )
+        .prop_map(|(secs, nsecs)| Utc.timestamp(secs, nsecs))
+}
+
+/// Returns a strategy that produces an arbitrary time from a [`u32`] number
+/// of seconds past the epoch.
+///
+/// The nanoseconds value is always zero.
+///
+/// The Zcash protocol typically uses 4-byte seconds values, except for the
+/// [`Version`] message.
+pub fn datetime_u32() -> impl Strategy<Value = chrono::DateTime<Utc>> {
+    any::<u32>().prop_map(|secs| Utc.timestamp(secs.into(), 0))
+}

zebra-chain/src/sprout/tree.rs

@@ -106,7 +106,7 @@ impl From<Root> for [u8; 32] {
 
 /// Sprout Note Commitment Tree
 #[derive(Clone, Debug, Default, Eq, PartialEq)]
-#[cfg_attr(test, derive(Arbitrary))]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 struct NoteCommitmentTree {
     /// The root node of the tree (often used as an anchor).
     root: Root,

zebra-network/Cargo.toml

@@ -40,4 +40,5 @@ proptest = "0.10"
 proptest-derive = "0.3"
 toml = "0.5"
 
+zebra-chain = { path = "../zebra-chain", features = ["proptest-impl"] }
 zebra-test = { path = "../zebra-test/" }

zebra-network/src/protocol/external/message.rs

@@ -14,6 +14,11 @@ use super::inv::InventoryHash;
 use super::types::*;
 use crate::meta_addr::MetaAddr;
 
+#[cfg(any(test, feature = "proptest-impl"))]
+use proptest_derive::Arbitrary;
+#[cfg(any(test, feature = "proptest-impl"))]
+use zebra_chain::serialization::arbitrary::datetime_full;
+
 /// A Bitcoin-like network message for the Zcash protocol.
 ///
 /// The Zcash network protocol is mostly inherited from Bitcoin, and a list of
@@ -31,6 +36,7 @@ use crate::meta_addr::MetaAddr;
 ///
 /// [btc_wiki_protocol]: https://en.bitcoin.it/wiki/Protocol_documentation
 #[derive(Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub enum Message {
     /// A `version` message.
     ///
@@ -47,6 +53,12 @@ pub enum Message {
         services: PeerServices,
 
         /// The time when the version message was sent.
+        ///
+        /// This is a 64-bit field. Zebra rejects out-of-range times as invalid.
+        #[cfg_attr(
+            any(test, feature = "proptest-impl"),
+            proptest(strategy = "datetime_full()")
+        )]
         timestamp: DateTime<Utc>,
 
         /// The network address of the node receiving this message, and its
@@ -307,6 +319,7 @@ where
 ///
 /// [Bitcoin reference](https://en.bitcoin.it/wiki/Protocol_documentation#reject)
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 #[repr(u8)]
 #[allow(missing_docs)]
 pub enum RejectReason {

zebra-network/src/protocol/external/types.rs

@@ -17,7 +17,7 @@ use proptest_derive::Arbitrary;
 
 /// A magic number identifying the network.
 #[derive(Copy, Clone, Eq, PartialEq)]
-#[cfg_attr(test, derive(Arbitrary))]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct Magic(pub [u8; 4]);
 
 impl fmt::Debug for Magic {
@@ -38,6 +38,7 @@ impl From<Network> for Magic {
 
 /// A protocol version number.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct Version(pub u32);
 
 impl Version {
@@ -89,6 +90,7 @@ bitflags! {
 
 /// A nonce used in the networking layer to identify messages.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct Nonce(pub u64);
 
 impl Default for Nonce {
@@ -100,6 +102,7 @@ impl Default for Nonce {
 
 /// A random value to add to the seed value in a hash function.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct Tweak(pub u32);
 
 impl Default for Tweak {
@@ -112,6 +115,7 @@ impl Default for Tweak {
 /// A Bloom filter consisting of a bit field of arbitrary byte-aligned
 /// size, maximum size is 36,000 bytes.
 #[derive(Clone, Debug, Eq, PartialEq)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub struct Filter(pub Vec<u8>);
 
 #[cfg(test)]

zebra-network/src/protocol/internal/request.rs

@@ -7,6 +7,9 @@ use zebra_chain::{
 
 use super::super::types::Nonce;
 
+#[cfg(any(test, feature = "proptest-impl"))]
+use proptest_derive::Arbitrary;
+
 /// A network request, represented in internal format.
 ///
 /// The network layer aims to abstract away the details of the Bitcoin wire
@@ -27,6 +30,7 @@ use super::super::types::Nonce;
 /// a best-effort attempt to ignore any messages responsive to the cancelled
 /// request, subject to limitations in the underlying Zcash protocol.
 #[derive(Clone, Debug)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub enum Request {
     /// Requests additional peers from the server.
     ///

zebra-network/src/protocol/internal/response.rs

@@ -4,10 +4,15 @@ use zebra_chain::{
 };
 
 use crate::meta_addr::MetaAddr;
+
 use std::sync::Arc;
 
+#[cfg(any(test, feature = "proptest-impl"))]
+use proptest_derive::Arbitrary;
+
 /// A response to a network request, represented in internal format.
 #[derive(Clone, Debug)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 pub enum Response {
     /// Do not send any response to this request.
     ///