change(scan): Refactor scanning tests (#8047)

* Derive & impl helper traits from `std`

* Create `compact_to_v4` fn

* Create `fake_block` fn

* Refactor existing tests to use the new functions

* Cosmetics

* Refactor docs

* Put `Default` behind `cfg_attr(test)`

Rationale
---------

We avoid implementing `Default` on consensus-critical types because it's
easy to miss an incorrect use in a review. It's easy to hide a
`default()` in a call like `unwrap_or_default()` or even more subtle
methods.

---------

Co-authored-by: teor <[email protected]>

Cargo.lock

@@ -5798,6 +5798,7 @@ name = "zebra-scan"
 version = "0.1.0-alpha.0"
 dependencies = [
  "bls12_381",
+ "chrono",
  "color-eyre",
  "ff",
  "group",

zebra-chain/src/amount.rs

@@ -491,7 +491,7 @@ impl Error {
 ///     -MAX_MONEY..=MAX_MONEY,
 /// );
 /// ```
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Default)]
 pub struct NegativeAllowed;
 
 impl Constraint for NegativeAllowed {

zebra-chain/src/block/hash.rs

@@ -21,7 +21,7 @@ use proptest_derive::Arbitrary;
 /// Note: Zebra displays transaction and block hashes in big-endian byte-order,
 /// following the u256 convention set by Bitcoin and zcashd.
 #[derive(Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
-#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary, Default))]
 pub struct Hash(pub [u8; 32]);
 
 impl Hash {

zebra-chain/src/block/merkle.rs

@@ -70,7 +70,7 @@ use proptest_derive::Arbitrary;
 ///
 /// [ZIP-244]: https://zips.z.cash/zip-0244
 #[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize)]
-#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary, Default))]
 pub struct Root(pub [u8; 32]);
 
 impl fmt::Debug for Root {

zebra-chain/src/fmt.rs

@@ -163,7 +163,7 @@ where
 
 /// Wrapper to override `Debug`, redirecting it to hex-encode the type.
 /// The type must implement `AsRef<[u8]>`.
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Default)]
 #[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
 #[serde(transparent)]
 pub struct HexDebug<T: AsRef<[u8]>>(pub T);

zebra-chain/src/sapling.rs

@@ -24,7 +24,9 @@ pub mod shielded_data;
 pub mod spend;
 pub mod tree;
 
-pub use commitment::{CommitmentRandomness, NoteCommitment, ValueCommitment};
+pub use commitment::{
+    CommitmentRandomness, NotSmallOrderValueCommitment, NoteCommitment, ValueCommitment,
+};
 pub use keys::Diversifier;
 pub use note::{EncryptedNote, Note, Nullifier, WrappedNoteKey};
 pub use output::{Output, OutputInTransactionV4, OutputPrefixInTransactionV5};

zebra-chain/src/sapling/commitment.rs

@@ -158,6 +158,7 @@ impl NoteCommitment {
 ///
 /// <https://zips.z.cash/protocol/protocol.pdf#concretehomomorphiccommit>
 #[derive(Clone, Copy, Deserialize, PartialEq, Eq, Serialize)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Default))]
 pub struct ValueCommitment(#[serde(with = "serde_helpers::AffinePoint")] jubjub::AffinePoint);
 
 impl<'a> std::ops::Add<&'a ValueCommitment> for ValueCommitment {
@@ -302,6 +303,7 @@ lazy_static! {
 /// <https://zips.z.cash/protocol/protocol.pdf#spenddesc>
 /// <https://zips.z.cash/protocol/protocol.pdf#outputdesc>
 #[derive(Debug, Clone, Copy, Deserialize, PartialEq, Eq, Serialize)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Default))]
 pub struct NotSmallOrderValueCommitment(ValueCommitment);
 
 impl TryFrom<ValueCommitment> for NotSmallOrderValueCommitment {

zebra-chain/src/sapling/note/ciphertexts.rs

@@ -12,6 +12,12 @@ use crate::serialization::{SerializationError, ZcashDeserialize, ZcashSerialize}
 #[derive(Deserialize, Serialize)]
 pub struct EncryptedNote(#[serde(with = "BigArray")] pub(crate) [u8; 580]);
 
+impl From<[u8; 580]> for EncryptedNote {
+    fn from(byte_array: [u8; 580]) -> Self {
+        Self(byte_array)
+    }
+}
+
 impl fmt::Debug for EncryptedNote {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_tuple("EncryptedNote")
@@ -59,6 +65,12 @@ impl ZcashDeserialize for EncryptedNote {
 #[derive(Deserialize, Serialize)]
 pub struct WrappedNoteKey(#[serde(with = "BigArray")] pub(crate) [u8; 80]);
 
+impl From<[u8; 80]> for WrappedNoteKey {
+    fn from(byte_array: [u8; 80]) -> Self {
+        Self(byte_array)
+    }
+}
+
 impl fmt::Debug for WrappedNoteKey {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_tuple("WrappedNoteKey")

zebra-chain/src/work/difficulty.rs

@@ -63,6 +63,7 @@ mod tests;
 ///
 /// [section 7.7.4]: https://zips.z.cash/protocol/protocol.pdf#nbits
 #[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(any(test, feature = "proptest-impl"), derive(Default))]
 pub struct CompactDifficulty(pub(crate) u32);
 
 /// An invalid CompactDifficulty value, for testing.

zebra-chain/src/work/equihash.rs

@@ -93,6 +93,13 @@ impl Clone for Solution {
 
 impl Eq for Solution {}
 
+#[cfg(any(test, feature = "proptest-impl"))]
+impl Default for Solution {
+    fn default() -> Self {
+        Self([0; SOLUTION_SIZE])
+    }
+}
+
 impl ZcashSerialize for Solution {
     fn zcash_serialize<W: io::Write>(&self, writer: W) -> Result<(), io::Error> {
         zcash_serialize_bytes(&self.0.to_vec(), writer)

zebra-scan/Cargo.toml

@@ -35,6 +35,8 @@ zcash_primitives = "0.13.0-rc.1"
 zebra-chain = { path = "../zebra-chain", version = "1.0.0-beta.31" }
 zebra-state = { path = "../zebra-state", version = "1.0.0-beta.31", features = ["shielded-scan"] }
 
+chrono = { version = "0.4.31", default-features = false, features = ["clock", "std", "serde"] }
+
 [dev-dependencies]
 
 bls12_381 = "0.8.0"