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Implement Expanded to Compact Difficulty Conversion (#1196) 

* Implement Expanded to Compact Difficulty
* Implement Arbitrary for CompactDifficulty
Remove the derive, and generate values from random block
hashes.
* Implement Arbitrary for ExpandedDifficulty and Work
* Use Arbitrary for CompactDifficulty in Arbitrary for Block
* Test difficulty on all block test vectors
And cleanup some duplicate test code
* Round-trip tests for compact test cases
* Round-trip tests for compact difficulty in block test vectors
* Make Add for Work return PartialCumulativeWork
Remove AddAssign for Work
Rewrite a proptest using Sub for PartialCumulativeWork
Use Arbitrary for Work
* Add roundtrip work sum tests
* Add roundtrip comparison difficulty tests
* Add failing proptest cases due to test bugs
* Use Some(_) rather than _.into()
* Reduce visibility of difficulty type inner values
* Split work and other difficulty proptests
This change makes sure that rejected work values don't disable property
tests on other types.
This commit is contained in:
teor 2020-10-30 11:36:59 +10:00 committed by GitHub
parent f338048012
commit 1c31225aac
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 797 additions and 489 deletions
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7
zebra-chain/proptest-regressions/work/tests/prop.txt Normal file
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@ -0,0 +1,7 @@
# Seeds for failure cases proptest has generated in the past. It is
# automatically read and these particular cases re-run before any
# novel cases are generated.
#
# It is recommended to check this file in to source control so that
# everyone who runs the test benefits from these saved cases.
cc 8e9b7658e31f20a01083e3b065f8ca0cdc98fedaf3058405e9e9fb59fd90b570 # shrinks to expanded_seed = block::Hash("0000000000000000000000000000000000000000000000000000000000000000")

9
zebra-chain/src/block/arbitrary.rs
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@ -73,6 +73,7 @@ impl Arbitrary for Header {
any::<[u8; 32]>(), any::<[u8; 32]>(),
// time is interpreted as u32 in the spec, but rust timestamps are i64 // time is interpreted as u32 in the spec, but rust timestamps are i64
(0i64..(u32::MAX as i64)), (0i64..(u32::MAX as i64)),
any::<CompactDifficulty>(),
any::<[u8; 32]>(), any::<[u8; 32]>(),
any::<equihash::Solution>(), any::<equihash::Solution>(),
) )
@ -80,19 +81,19 @@ impl Arbitrary for Header {
|( |(
version, version,
previous_block_hash, previous_block_hash,
merkle_root_hash, merkle_root,
root_bytes, root_bytes,
timestamp, timestamp,
difficulty_threshold,
nonce, nonce,
solution, solution,
)| Header { )| Header {
version, version,
previous_block_hash, previous_block_hash,
merkle_root: merkle_root_hash, merkle_root,
root_bytes, root_bytes,
time: Utc.timestamp(timestamp, 0), time: Utc.timestamp(timestamp, 0),
// TODO: replace with `ExpandedDifficulty.to_compact` when that method is implemented difficulty_threshold,
difficulty_threshold: CompactDifficulty(545259519),
nonce, nonce,
solution, solution,
}, },

123
zebra-chain/src/work/difficulty.rs
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@ -13,14 +13,16 @@
use crate::{block, parameters::Network}; use crate::{block, parameters::Network};
use std::cmp::{Ordering, PartialEq, PartialOrd}; use std::{
use std::{fmt, ops::Add, ops::AddAssign}; cmp::{Ordering, PartialEq, PartialOrd},
convert::TryFrom,
fmt,
};
use primitive_types::U256; use primitive_types::U256;
#[cfg(any(test, feature = "proptest-impl"))] #[cfg(any(test, feature = "proptest-impl"))]
use proptest_derive::Arbitrary; mod arbitrary;
#[cfg(test)] #[cfg(test)]
mod tests; mod tests;
@ -53,8 +55,7 @@ mod tests;
/// multiple equivalent `CompactDifficulty` values, due to redundancy in the /// multiple equivalent `CompactDifficulty` values, due to redundancy in the
/// floating-point format. /// floating-point format.
#[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize)] #[derive(Clone, Copy, Eq, PartialEq, Serialize, Deserialize)]
#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))] pub struct CompactDifficulty(pub(crate) u32);
pub struct CompactDifficulty(pub u32);
impl fmt::Debug for CompactDifficulty { impl fmt::Debug for CompactDifficulty {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@ -65,6 +66,9 @@ impl fmt::Debug for CompactDifficulty {
} }
} }
/// An invalid CompactDifficulty value, for testing.
pub const INVALID_COMPACT_DIFFICULTY: CompactDifficulty = CompactDifficulty(u32::MAX);
/// A 256-bit unsigned "expanded difficulty" value. /// A 256-bit unsigned "expanded difficulty" value.
/// ///
/// Used as a target threshold for the difficulty of a `block::Hash`. /// Used as a target threshold for the difficulty of a `block::Hash`.
@ -74,13 +78,19 @@ impl fmt::Debug for CompactDifficulty {
/// The precise bit pattern of an `ExpandedDifficulty` value is /// The precise bit pattern of an `ExpandedDifficulty` value is
/// consensus-critical, because it is compared with the `block::Hash`. /// consensus-critical, because it is compared with the `block::Hash`.
/// ///
/// Note that each `CompactDifficulty` value represents a range of /// Note that each `CompactDifficulty` value can be converted from a
/// `ExpandedDifficulty` values, because the precision of the /// range of `ExpandedDifficulty` values, because the precision of
/// floating-point format requires rounding on conversion. /// the floating-point format requires rounding on conversion.
/// ///
/// Therefore, consensus-critical code must perform the specified /// Therefore, consensus-critical code must perform the specified
/// conversions to `CompactDifficulty`, even if the original /// conversions to `CompactDifficulty`, even if the original
/// `ExpandedDifficulty` values are known. /// `ExpandedDifficulty` values are known.
///
/// Callers should avoid constructing `ExpandedDifficulty` zero
/// values, because they are rejected by the consensus rules,
/// and cause some conversion functions to panic.
//
// TODO: Use NonZeroU256, when available
#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd)] #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd)]
pub struct ExpandedDifficulty(U256); pub struct ExpandedDifficulty(U256);
@ -236,7 +246,7 @@ impl CompactDifficulty {
// `((2^256 - expanded - 1) / (expanded + 1)) + 1`, or // `((2^256 - expanded - 1) / (expanded + 1)) + 1`, or
let result = (!expanded.0 / (expanded.0 + 1)) + 1; let result = (!expanded.0 / (expanded.0 + 1)) + 1;
if result <= u128::MAX.into() { if result <= u128::MAX.into() {
Work(result.as_u128()).into() Some(Work(result.as_u128()))
} else { } else {
None None
} }
@ -255,7 +265,7 @@ impl ExpandedDifficulty {
/// ///
/// Hashes are not used to calculate the difficulties of future blocks, so /// Hashes are not used to calculate the difficulties of future blocks, so
/// users of this module should avoid converting hashes into difficulties. /// users of this module should avoid converting hashes into difficulties.
fn from_hash(hash: &block::Hash) -> ExpandedDifficulty { pub(super) fn from_hash(hash: &block::Hash) -> ExpandedDifficulty {
U256::from_little_endian(&hash.0).into() U256::from_little_endian(&hash.0).into()
} }
@ -272,6 +282,73 @@ impl ExpandedDifficulty {
limit.into() limit.into()
} }
/// Calculate the CompactDifficulty for an expanded difficulty.
///
/// See `ToCompact()` in the Zcash Specification, and `GetCompact()`
/// in zcashd.
///
/// Panics:
///
/// If `self` is zero.
///
/// `ExpandedDifficulty` values are generated in two ways:
/// * conversion from `CompactDifficulty` values, which rejects zeroes, and
/// * difficulty adjustment calculations, which impose a non-zero minimum
/// `target_difficulty_limit`.
///
/// Neither of these methods yield zero values.
pub fn to_compact(&self) -> CompactDifficulty {
// The zcashd implementation supports negative and zero compact values.
// These values are rejected by the protocol rules. Zebra is designed so
// that invalid states are not representable. Therefore, this function
// does not produce negative compact values, and panics on zero compact
// values. (The negative compact value code in zcashd is unused.)
assert!(self.0 > 0.into(), "Zero difficulty values are invalid");
// The constants for this floating-point representation.
// Alias the constants here, so the code is easier to read.
const UNSIGNED_MANTISSA_MASK: u32 = CompactDifficulty::UNSIGNED_MANTISSA_MASK;
const OFFSET: i32 = CompactDifficulty::OFFSET;
// Calculate the final size, accounting for the sign bit.
// This is the size *after* applying the sign bit adjustment in `ToCompact()`.
let size = self.0.bits() / 8 + 1;
// Make sure the mantissa is non-negative, by shifting down values that
// would otherwise overflow into the sign bit
let mantissa = if self.0 <= UNSIGNED_MANTISSA_MASK.into() {
// Value is small, shift up if needed
self.0 << (8 * (3 - size))
} else {
// Value is large, shift down
self.0 >> (8 * (size - 3))
};
// This assertion also makes sure that size fits in its 8 bit compact field
assert!(
size < (31 + OFFSET) as _,
format!(
"256^size (256^{}) must fit in a u256, after the sign bit adjustment and offset",
size
)
);
let size = u32::try_from(size).expect("a 0-6 bit value fits in a u32");
assert!(
mantissa <= UNSIGNED_MANTISSA_MASK.into(),
format!("mantissa {:x?} must fit in its compact field", mantissa)
);
let mantissa = u32::try_from(mantissa).expect("a 0-23 bit value fits in a u32");
if mantissa > 0 {
CompactDifficulty(mantissa + (size << 24))
} else {
// This check catches invalid mantissas. Overflows and underflows
// should also be unreachable, but they aren't caught here.
unreachable!("converted CompactDifficulty values must be valid")
}
}
} }
impl From<U256> for ExpandedDifficulty { impl From<U256> for ExpandedDifficulty {
@ -328,21 +405,11 @@ impl PartialOrd<ExpandedDifficulty> for block::Hash {
} }
} }
impl Add for Work { impl std::ops::Add for Work {
type Output = Self; type Output = PartialCumulativeWork;
fn add(self, rhs: Work) -> Self { fn add(self, rhs: Work) -> PartialCumulativeWork {
let result = self PartialCumulativeWork::from(self) + rhs
.0
.checked_add(rhs.0)
.expect("Work values do not overflow");
Work(result)
}
}
impl AddAssign for Work {
fn add_assign(&mut self, rhs: Work) {
*self = *self + rhs;
} }
} }
@ -350,6 +417,12 @@ impl AddAssign for Work {
/// Partial work used to track relative work in non-finalized chains /// Partial work used to track relative work in non-finalized chains
pub struct PartialCumulativeWork(u128); pub struct PartialCumulativeWork(u128);
impl From<Work> for PartialCumulativeWork {
fn from(work: Work) -> Self {
PartialCumulativeWork(work.0)
}
}
impl std::ops::Add<Work> for PartialCumulativeWork { impl std::ops::Add<Work> for PartialCumulativeWork {
type Output = PartialCumulativeWork; type Output = PartialCumulativeWork;

83
zebra-chain/src/work/difficulty/arbitrary.rs Normal file
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@ -0,0 +1,83 @@
use super::*;
use crate::block;
use proptest::{arbitrary::Arbitrary, collection::vec, prelude::*};
impl Arbitrary for CompactDifficulty {
type Parameters = ();
fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
(vec(any::<u8>(), 32))
.prop_filter_map("zero CompactDifficulty values are invalid", |v| {
let mut bytes = [0; 32];
bytes.copy_from_slice(v.as_slice());
if bytes == [0; 32] {
return None;
}
// In the Zcash protocol, a CompactDifficulty is generated using the difficulty
// adjustment functions. Instead of using those functions, we make a random
// ExpandedDifficulty, then convert it to a CompactDifficulty.
ExpandedDifficulty::from_hash(&block::Hash(bytes))
.to_compact()
.into()
})
.boxed()
}
type Strategy = BoxedStrategy<Self>;
}
impl Arbitrary for ExpandedDifficulty {
type Parameters = ();
fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
any::<CompactDifficulty>()
.prop_map(|d| {
// In the Zcash protocol, an ExpandedDifficulty is converted from a CompactDifficulty,
// or generated using the difficulty adjustment functions. We use the conversion in
// our proptest strategy.
d.to_expanded()
.expect("arbitrary CompactDifficulty is valid")
})
.boxed()
}
type Strategy = BoxedStrategy<Self>;
}
impl Arbitrary for Work {
type Parameters = ();
fn arbitrary_with(_args: ()) -> Self::Strategy {
// In the Zcash protocol, a Work is converted from an ExpandedDifficulty.
// But some randomised difficulties are impractically large, and will
// never appear in any real-world block. So we just use a random Work value.
(any::<u128>())
.prop_filter_map("zero Work values are invalid", |w| {
if w == 0 {
None
} else {
Work(w).into()
}
})
.boxed()
}
type Strategy = BoxedStrategy<Self>;
}
impl Arbitrary for PartialCumulativeWork {
type Parameters = ();
fn arbitrary_with(_args: ()) -> Self::Strategy {
// In Zebra's implementation, a PartialCumulativeWork is the sum of 0..100 Work values.
// But our Work values are randomised, rather than being derived from real-world
// difficulties. So we don't need to sum multiple Work values here.
(any::<Work>())
.prop_map(PartialCumulativeWork::from)
.boxed()
}
type Strategy = BoxedStrategy<Self>;
}

460
zebra-chain/src/work/difficulty/tests.rs
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@ -1,458 +1,2 @@
use super::*; mod prop;
mod vectors;
use crate::block::Block;
use crate::serialization::ZcashDeserialize;
use color_eyre::eyre::Report;
use proptest::prelude::*;
use std::sync::Arc;
// Alias the struct constants here, so the code is easier to read.
const PRECISION: u32 = CompactDifficulty::PRECISION;
const SIGN_BIT: u32 = CompactDifficulty::SIGN_BIT;
const UNSIGNED_MANTISSA_MASK: u32 = CompactDifficulty::UNSIGNED_MANTISSA_MASK;
const OFFSET: i32 = CompactDifficulty::OFFSET;
impl Arbitrary for ExpandedDifficulty {
type Parameters = ();
fn arbitrary_with(_args: ()) -> Self::Strategy {
(any::<[u8; 32]>())
.prop_map(|v| ExpandedDifficulty(U256::from_little_endian(&v)))
.boxed()
}
type Strategy = BoxedStrategy<Self>;
}
impl Arbitrary for Work {
type Parameters = ();
fn arbitrary_with(_args: ()) -> Self::Strategy {
(any::<u128>()).prop_map(Work).boxed()
}
type Strategy = BoxedStrategy<Self>;
}
/// Test debug formatting.
#[test]
fn debug_format() {
zebra_test::init();
assert_eq!(
format!("{:?}", CompactDifficulty(0)),
"CompactDifficulty(0x00000000)"
);
assert_eq!(
format!("{:?}", CompactDifficulty(1)),
"CompactDifficulty(0x00000001)"
);
assert_eq!(
format!("{:?}", CompactDifficulty(u32::MAX)),
"CompactDifficulty(0xffffffff)"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::zero())),
"ExpandedDifficulty(\"0000000000000000000000000000000000000000000000000000000000000000\")"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::one())),
"ExpandedDifficulty(\"0100000000000000000000000000000000000000000000000000000000000000\")"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::MAX)),
"ExpandedDifficulty(\"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff\")"
);
assert_eq!(format!("{:?}", Work(0)), "Work(0x0, 0, -inf)");
assert_eq!(
format!("{:?}", Work(u8::MAX as u128)),
"Work(0xff, 255, 7.99435)"
);
assert_eq!(
format!("{:?}", Work(u64::MAX as u128)),
"Work(0xffffffffffffffff, 18446744073709551615, 64.00000)"
);
assert_eq!(
format!("{:?}", Work(u128::MAX)),
"Work(0xffffffffffffffffffffffffffffffff, 340282366920938463463374607431768211455, 128.00000)"
);
}
/// Test zero values for CompactDifficulty.
#[test]
fn compact_zero() {
zebra_test::init();
let natural_zero = CompactDifficulty(0);
assert_eq!(natural_zero.to_expanded(), None);
assert_eq!(natural_zero.to_work(), None);
// Small value zeroes
let small_zero_1 = CompactDifficulty(1);
assert_eq!(small_zero_1.to_expanded(), None);
assert_eq!(small_zero_1.to_work(), None);
let small_zero_max = CompactDifficulty(UNSIGNED_MANTISSA_MASK);
assert_eq!(small_zero_max.to_expanded(), None);
assert_eq!(small_zero_max.to_work(), None);
// Special-cased zeroes, negative in the floating-point representation
let sc_zero = CompactDifficulty(SIGN_BIT);
assert_eq!(sc_zero.to_expanded(), None);
assert_eq!(sc_zero.to_work(), None);
let sc_zero_next = CompactDifficulty(SIGN_BIT + 1);
assert_eq!(sc_zero_next.to_expanded(), None);
assert_eq!(sc_zero_next.to_work(), None);
let sc_zero_high = CompactDifficulty((1 << PRECISION) - 1);
assert_eq!(sc_zero_high.to_expanded(), None);
assert_eq!(sc_zero_high.to_work(), None);
let sc_zero_max = CompactDifficulty(u32::MAX);
assert_eq!(sc_zero_max.to_expanded(), None);
assert_eq!(sc_zero_max.to_work(), None);
}
/// Test extreme values for CompactDifficulty.
#[test]
fn compact_extremes() {
zebra_test::init();
// Values equal to one
let expanded_one = Some(ExpandedDifficulty(U256::one()));
let work_one = None;
let one = CompactDifficulty(OFFSET as u32 * (1 << PRECISION) + 1);
assert_eq!(one.to_expanded(), expanded_one);
assert_eq!(one.to_work(), work_one);
let another_one = CompactDifficulty((1 << PRECISION) + (1 << 16));
assert_eq!(another_one.to_expanded(), expanded_one);
assert_eq!(another_one.to_work(), work_one);
// Maximum mantissa
let expanded_mant = Some(ExpandedDifficulty(UNSIGNED_MANTISSA_MASK.into()));
let work_mant = None;
let mant = CompactDifficulty(OFFSET as u32 * (1 << PRECISION) + UNSIGNED_MANTISSA_MASK);
assert_eq!(mant.to_expanded(), expanded_mant);
assert_eq!(mant.to_work(), work_mant);
// Maximum valid exponent
let exponent: U256 = (31 * 8).into();
let u256_exp = U256::from(2).pow(exponent);
let expanded_exp = Some(ExpandedDifficulty(u256_exp));
let work_exp = Some(Work(
((U256::MAX - u256_exp) / (u256_exp + 1) + 1).as_u128(),
));
let exp = CompactDifficulty((31 + OFFSET as u32) * (1 << PRECISION) + 1);
assert_eq!(exp.to_expanded(), expanded_exp);
assert_eq!(exp.to_work(), work_exp);
// Maximum valid mantissa and exponent
let exponent: U256 = (29 * 8).into();
let u256_me = U256::from(UNSIGNED_MANTISSA_MASK) * U256::from(2).pow(exponent);
let expanded_me = Some(ExpandedDifficulty(u256_me));
let work_me = Some(Work((!u256_me / (u256_me + 1) + 1).as_u128()));
let me = CompactDifficulty((31 + 1) * (1 << PRECISION) + UNSIGNED_MANTISSA_MASK);
assert_eq!(me.to_expanded(), expanded_me);
assert_eq!(me.to_work(), work_me);
// Maximum value, at least according to the spec
//
// According to ToTarget() in the spec, this value is
// `(2^23 - 1) * 256^253`, which is larger than the maximum expanded
// value. Therefore, a block can never pass with this threshold.
//
// zcashd rejects these blocks without comparing the hash.
let difficulty_max = CompactDifficulty(u32::MAX & !SIGN_BIT);
assert_eq!(difficulty_max.to_expanded(), None);
assert_eq!(difficulty_max.to_work(), None);
// Bitcoin test vectors for CompactDifficulty
// See https://developer.bitcoin.org/reference/block_chain.html#target-nbits
// These values are not in the table below, because they do not fit in u128
//
// The minimum difficulty on the bitcoin mainnet and testnet
let difficulty_btc_main = CompactDifficulty(0x1d00ffff);
let u256_btc_main = U256::from(0xffff) << 208;
let expanded_btc_main = Some(ExpandedDifficulty(u256_btc_main));
let work_btc_main = Some(Work(0x100010001));
assert_eq!(difficulty_btc_main.to_expanded(), expanded_btc_main);
assert_eq!(difficulty_btc_main.to_work(), work_btc_main);
// The minimum difficulty in bitcoin regtest
// This is also the easiest respesentable difficulty
let difficulty_btc_reg = CompactDifficulty(0x207fffff);
let u256_btc_reg = U256::from(0x7fffff) << 232;
let expanded_btc_reg = Some(ExpandedDifficulty(u256_btc_reg));
let work_btc_reg = Some(Work(0x2));
assert_eq!(difficulty_btc_reg.to_expanded(), expanded_btc_reg);
assert_eq!(difficulty_btc_reg.to_work(), work_btc_reg);
}
/// Bitcoin test vectors for CompactDifficulty, and their corresponding
/// ExpandedDifficulty and Work values.
/// See https://developer.bitcoin.org/reference/block_chain.html#target-nbits
static COMPACT_DIFFICULTY_CASES: &[(u32, Option<u128>, Option<u128>)] = &[
// These Work values will never happen in practice, because the corresponding
// difficulties are extremely high. So it is ok for us to reject them.
(0x01003456, None /* 0x00 */, None),
(0x01123456, Some(0x12), None),
(0x02008000, Some(0x80), None),
(0x05009234, Some(0x92340000), None),
(0x04923456, None /* -0x12345600 */, None),
(0x04123456, Some(0x12345600), None),
];
/// Test Bitcoin test vectors for CompactDifficulty.
#[test]
#[spandoc::spandoc]
fn compact_bitcoin_test_vectors() {
zebra_test::init();
// We use two spans, so we can diagnose conversion panics, and mismatching results
for (compact, expected_expanded, expected_work) in COMPACT_DIFFICULTY_CASES.iter().cloned() {
/// SPANDOC: Convert compact to expanded and work {?compact, ?expected_expanded, ?expected_work}
{
let expected_expanded = expected_expanded.map(U256::from).map(ExpandedDifficulty);
let expected_work = expected_work.map(Work);
let compact = CompactDifficulty(compact);
let actual_expanded = compact.to_expanded();
let actual_work = compact.to_work();
/// SPANDOC: Test that compact produces the expected expanded and work {?compact, ?expected_expanded, ?actual_expanded, ?expected_work, ?actual_work}
{
assert_eq!(actual_expanded, expected_expanded);
assert_eq!(actual_work, expected_work);
}
}
}
}
/// Test blocks using CompactDifficulty.
#[test]
#[spandoc::spandoc]
fn block_difficulty() -> Result<(), Report> {
zebra_test::init();
let mut blockchain = Vec::new();
for b in &[
&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_1_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_2_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_3_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_4_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_5_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_6_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_7_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_8_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_9_BYTES[..],
&zebra_test::vectors::BLOCK_MAINNET_10_BYTES[..],
] {
let block = Arc::<Block>::zcash_deserialize(*b)?;
let hash = block.hash();
blockchain.push((block.clone(), block.coinbase_height().unwrap(), hash));
}
let diff_zero = ExpandedDifficulty(U256::zero());
let diff_one = ExpandedDifficulty(U256::one());
let diff_max = ExpandedDifficulty(U256::MAX);
let work_zero = Work(0);
let work_max = Work(u128::MAX);
let mut cumulative_work = Work::default();
let mut previous_cumulative_work = Work::default();
for (block, height, hash) in blockchain {
/// SPANDOC: Calculate the threshold for mainnet block {?height}
let threshold = block
.header
.difficulty_threshold
.to_expanded()
.expect("Chain blocks have valid difficulty thresholds.");
/// SPANDOC: Check the difficulty for mainnet block {?height, ?threshold, ?hash}
{
assert!(hash <= threshold);
// also check the comparison operators work
assert!(hash > diff_zero);
assert!(hash > diff_one);
assert!(hash < diff_max);
}
/// SPANDOC: Check the work for mainnet block {?height}
{
let work = block
.header
.difficulty_threshold
.to_work()
.expect("Chain blocks have valid work.");
// also check the comparison operators work
assert!(work > work_zero);
assert!(work < work_max);
cumulative_work += work;
assert!(cumulative_work > work_zero);
assert!(cumulative_work < work_max);
assert!(cumulative_work > previous_cumulative_work);
previous_cumulative_work = cumulative_work;
}
/// SPANDOC: Calculate the work for mainnet block {?height}
let _work = block
.header
.difficulty_threshold
.to_work()
.expect("Chain blocks have valid work.");
// TODO: check work comparison operators and cumulative work addition
}
Ok(())
}
/// Test ExpandedDifficulty ordering
#[test]
#[spandoc::spandoc]
#[allow(clippy::eq_op)]
fn expanded_order() -> Result<(), Report> {
zebra_test::init();
let zero = ExpandedDifficulty(U256::zero());
let one = ExpandedDifficulty(U256::one());
let max_value = ExpandedDifficulty(U256::MAX);
assert!(zero < one);
assert!(zero < max_value);
assert!(one < max_value);
assert_eq!(zero, zero);
assert!(zero <= one);
assert!(one >= zero);
assert!(one > zero);
Ok(())
}
/// Test ExpandedDifficulty and block::Hash ordering
#[test]
#[spandoc::spandoc]
fn expanded_hash_order() -> Result<(), Report> {
zebra_test::init();
let ex_zero = ExpandedDifficulty(U256::zero());
let ex_one = ExpandedDifficulty(U256::one());
let ex_max = ExpandedDifficulty(U256::MAX);
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
assert_eq!(hash_zero, ex_zero);
assert!(hash_zero < ex_one);
assert!(hash_zero < ex_max);
assert!(hash_max > ex_zero);
assert!(hash_max > ex_one);
assert_eq!(hash_max, ex_max);
assert!(ex_one > hash_zero);
assert!(ex_one < hash_max);
assert!(hash_zero >= ex_zero);
assert!(ex_zero >= hash_zero);
assert!(hash_zero <= ex_zero);
assert!(ex_zero <= hash_zero);
Ok(())
}
proptest! {
/// Check that CompactDifficulty expands, and converts to work.
///
/// Make sure the conversions don't panic, and that they compare correctly.
#[test]
fn prop_compact_expand_work(compact in any::<CompactDifficulty>()) {
// TODO: use random ExpandedDifficulties, once we have ExpandedDifficulty::to_compact()
//
// This change will increase the number of valid random work values.
let expanded = compact.to_expanded();
let work = compact.to_work();
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
let work_zero = Work(0);
let work_max = Work(u128::MAX);
if let Some(expanded) = expanded {
prop_assert!(expanded >= hash_zero);
prop_assert!(expanded <= hash_max);
}
if let Some(work) = work {
prop_assert!(work > work_zero);
prop_assert!(work < work_max);
}
}
/// Check that a random ExpandedDifficulty compares correctly with fixed block::Hash
#[test]
fn prop_expanded_order(expanded in any::<ExpandedDifficulty>()) {
// TODO: round-trip test, once we have ExpandedDifficulty::to_compact()
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
prop_assert!(expanded >= hash_zero);
prop_assert!(expanded <= hash_max);
}
/// Check that ExpandedDifficulty compares correctly with a random block::Hash.
#[test]
fn prop_hash_order(hash in any::<block::Hash>()) {
let ex_zero = ExpandedDifficulty(U256::zero());
let ex_one = ExpandedDifficulty(U256::one());
let ex_max = ExpandedDifficulty(U256::MAX);
prop_assert!(hash >= ex_zero);
prop_assert!(hash <= ex_max);
prop_assert!(hash >= ex_one || hash == ex_zero);
}
/// Check that a random ExpandedDifficulty and block::Hash compare correctly.
#[test]
#[allow(clippy::double_comparisons)]
fn prop_expanded_hash_order(expanded in any::<ExpandedDifficulty>(), hash in any::<block::Hash>()) {
prop_assert!(expanded < hash || expanded > hash || expanded == hash);
}
/// Check that the work values for two random ExpandedDifficulties add
/// correctly.
#[test]
fn prop_work(compact1 in any::<CompactDifficulty>(), compact2 in any::<CompactDifficulty>()) {
// TODO: use random ExpandedDifficulties, once we have ExpandedDifficulty::to_compact()
//
// This change will increase the number of valid random work values.
let work1 = compact1.to_work();
let work2 = compact2.to_work();
if let (Some(work1), Some(work2)) = (work1, work2) {
let work_limit = Work(u128::MAX/2);
if work1 < work_limit && work2 < work_limit {
let work_total = work1 + work2;
prop_assert!(work_total >= work1);
prop_assert!(work_total >= work2);
} else if work1 < work_limit {
let work_total = work1 + work1;
prop_assert!(work_total >= work1);
} else if work2 < work_limit {
let work_total = work2 + work2;
prop_assert!(work_total >= work2);
}
}
}
}

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use primitive_types::U256;
use proptest::{arbitrary::any, prelude::*};
use std::cmp::Ordering;
use crate::block;
use super::super::*;
proptest! {
/// Check Expanded, Compact, and Work conversions.
///
/// Make sure the conversions don't panic, and that they round-trip and compare
/// correctly.
#[test]
fn prop_difficulty_conversion(expanded_seed in any::<block::Hash>()) {
let expanded_seed = ExpandedDifficulty::from_hash(&expanded_seed);
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
prop_assert!(expanded_seed >= hash_zero);
prop_assert!(expanded_seed <= hash_max);
// Skip invalid seeds
prop_assume!(expanded_seed != hash_zero);
let compact = expanded_seed.to_compact();
let expanded_trunc = compact.to_expanded();
let work = compact.to_work();
if let Some(expanded_trunc) = expanded_trunc {
// zero compact values are invalid, and return None on conversion
prop_assert!(expanded_trunc > hash_zero);
// the maximum compact value has less precision than a hash
prop_assert!(expanded_trunc < hash_max);
// the truncated value should be less than or equal to the seed
prop_assert!(expanded_trunc <= expanded_seed);
// roundtrip
let compact_trip = expanded_trunc.to_compact();
prop_assert_eq!(compact, compact_trip);
let expanded_trip = compact_trip.to_expanded().expect("roundtrip expanded is valid");
prop_assert_eq!(expanded_trunc, expanded_trip);
// Some impossibly hard compact values are not valid work values in Zebra
if let Some(work) = work {
// roundtrip
let work_trip = compact_trip.to_work().expect("roundtrip work is valid if work is valid");
prop_assert_eq!(work, work_trip);
}
}
}
/// Check Work and PartialCumulativeWork conversions.
///
/// Make sure the conversions don't panic, and that they compare correctly.
#[test]
fn prop_work_conversion(work in any::<Work>()) {
let work_zero = Work(0);
let work_max = Work(u128::MAX);
prop_assert!(work > work_zero);
// similarly, the maximum compact value has less precision than work
prop_assert!(work < work_max);
let partial_work = PartialCumulativeWork::from(work);
prop_assert!(partial_work > PartialCumulativeWork::from(work_zero));
prop_assert!(partial_work < PartialCumulativeWork::from(work_max));
// Now try adding zero to convert to PartialCumulativeWork
prop_assert!(partial_work > work_zero + work_zero);
prop_assert!(partial_work < work_max + work_zero);
}
/// Check that a random ExpandedDifficulty compares correctly with fixed block::Hash
#[test]
fn prop_expanded_cmp(expanded in any::<ExpandedDifficulty>()) {
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
// zero compact values are invalid, and return None on conversion
prop_assert!(expanded > hash_zero);
// the maximum compact value has less precision than a hash
prop_assert!(expanded < hash_max);
}
/// Check that ExpandedDifficulty compares correctly with a random block::Hash.
#[test]
fn prop_hash_cmp(hash in any::<block::Hash>()) {
let ex_zero = ExpandedDifficulty(U256::zero());
let ex_one = ExpandedDifficulty(U256::one());
let ex_max = ExpandedDifficulty(U256::MAX);
prop_assert!(hash >= ex_zero);
prop_assert!(hash <= ex_max);
prop_assert!(hash >= ex_one || hash == ex_zero);
}
/// Check that a random ExpandedDifficulty and block::Hash compare without panicking.
#[test]
#[allow(clippy::double_comparisons)]
fn prop_expanded_hash_cmp(expanded in any::<ExpandedDifficulty>(), hash in any::<block::Hash>()) {
prop_assert!(expanded < hash || expanded > hash || expanded == hash);
}
/// Check that two random CompactDifficulty values compare and round-trip correctly.
#[test]
#[allow(clippy::double_comparisons)]
fn prop_compact_roundtrip(compact1 in any::<CompactDifficulty>(), compact2 in any::<CompactDifficulty>()) {
prop_assert!(compact1 != compact2 || compact1 == compact2);
let expanded1 = compact1.to_expanded().expect("arbitrary compact values are valid");
let expanded2 = compact2.to_expanded().expect("arbitrary compact values are valid");
if expanded1 != expanded2 {
prop_assert!(compact1 != compact2);
} else {
prop_assert!(compact1 == compact2);
}
let compact1_trip = expanded1.to_compact();
let compact2_trip = expanded2.to_compact();
if compact1_trip != compact2_trip {
prop_assert!(compact1 != compact2);
} else {
prop_assert!(compact1 == compact2);
}
}
/// Check that two random ExpandedDifficulty values compare and round-trip correctly.
#[test]
fn prop_expanded_roundtrip(expanded1_seed in any::<block::Hash>(), expanded2_seed in any::<block::Hash>()) {
let expanded1_seed = ExpandedDifficulty::from_hash(&expanded1_seed);
let expanded2_seed = ExpandedDifficulty::from_hash(&expanded2_seed);
// Skip invalid seeds
let expanded_zero = ExpandedDifficulty(U256::zero());
prop_assume!(expanded1_seed != expanded_zero);
prop_assume!(expanded2_seed != expanded_zero);
let compact1 = expanded1_seed.to_compact();
let compact2 = expanded2_seed.to_compact();
let expanded1_trunc = compact1.to_expanded();
let expanded2_trunc = compact2.to_expanded();
let work1 = compact1.to_work();
let work2 = compact2.to_work();
match expanded1_seed.cmp(&expanded2_seed) {
Ordering::Greater => {
// seed to compact truncation can turn expanded and work inequalities into equalities
prop_assert!(expanded1_trunc >= expanded2_trunc);
}
Ordering::Equal => {
prop_assert!(compact1 == compact2);
prop_assert!(expanded1_trunc == expanded2_trunc);
}
Ordering::Less => {
prop_assert!(expanded1_trunc <= expanded2_trunc);
}
}
if expanded1_trunc == expanded2_trunc {
prop_assert!(compact1 == compact2);
}
// Skip impossibly hard work values
prop_assume!(work1.is_some());
prop_assume!(work2.is_some());
match expanded1_seed.cmp(&expanded2_seed) {
Ordering::Greater => {
// work comparisons are reversed, because conversion involves division
prop_assert!(work1 <= work2);
}
Ordering::Equal => {
prop_assert!(work1 == work2);
}
Ordering::Less => {
prop_assert!(work1 >= work2);
}
}
match expanded1_trunc.cmp(&expanded2_trunc) {
Ordering::Greater => {
// expanded to work truncation can turn work inequalities into equalities
prop_assert!(work1 <= work2);
}
Ordering::Equal => {
prop_assert!(work1 == work2);
}
Ordering::Less => {
prop_assert!(work1 >= work2);
}
}
}
/// Check that two random Work values compare, add, and subtract correctly.
#[test]
fn prop_work_sum(work1 in any::<Work>(), work2 in any::<Work>()) {
// If the sum won't panic
if work1.0.checked_add(work2.0).is_some() {
let work_total = work1 + work2;
prop_assert!(work_total >= PartialCumulativeWork::from(work1));
prop_assert!(work_total >= PartialCumulativeWork::from(work2));
prop_assert_eq!(work_total - work1, PartialCumulativeWork::from(work2));
prop_assert_eq!(work_total - work2, PartialCumulativeWork::from(work1));
}
if work1.0.checked_add(work1.0).is_some() {
let work_total = work1 + work1;
prop_assert!(work_total >= PartialCumulativeWork::from(work1));
prop_assert_eq!(work_total - work1, PartialCumulativeWork::from(work1));
}
if work2.0.checked_add(work2.0).is_some() {
let work_total = work2 + work2;
prop_assert!(work_total >= PartialCumulativeWork::from(work2));
prop_assert_eq!(work_total - work2, PartialCumulativeWork::from(work2));
}
}
}

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use color_eyre::eyre::Report;
use std::sync::Arc;
use crate::block::Block;
use crate::serialization::ZcashDeserialize;
use super::super::*;
// Alias the struct constants here, so the code is easier to read.
const PRECISION: u32 = CompactDifficulty::PRECISION;
const SIGN_BIT: u32 = CompactDifficulty::SIGN_BIT;
const UNSIGNED_MANTISSA_MASK: u32 = CompactDifficulty::UNSIGNED_MANTISSA_MASK;
const OFFSET: i32 = CompactDifficulty::OFFSET;
/// Test debug formatting.
#[test]
fn debug_format() {
zebra_test::init();
assert_eq!(
format!("{:?}", CompactDifficulty(0)),
"CompactDifficulty(0x00000000)"
);
assert_eq!(
format!("{:?}", CompactDifficulty(1)),
"CompactDifficulty(0x00000001)"
);
assert_eq!(
format!("{:?}", CompactDifficulty(u32::MAX)),
"CompactDifficulty(0xffffffff)"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::zero())),
"ExpandedDifficulty(\"0000000000000000000000000000000000000000000000000000000000000000\")"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::one())),
"ExpandedDifficulty(\"0100000000000000000000000000000000000000000000000000000000000000\")"
);
assert_eq!(
format!("{:?}", ExpandedDifficulty(U256::MAX)),
"ExpandedDifficulty(\"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff\")"
);
assert_eq!(format!("{:?}", Work(0)), "Work(0x0, 0, -inf)");
assert_eq!(
format!("{:?}", Work(u8::MAX as u128)),
"Work(0xff, 255, 7.99435)"
);
assert_eq!(
format!("{:?}", Work(u64::MAX as u128)),
"Work(0xffffffffffffffff, 18446744073709551615, 64.00000)"
);
assert_eq!(
format!("{:?}", Work(u128::MAX)),
"Work(0xffffffffffffffffffffffffffffffff, 340282366920938463463374607431768211455, 128.00000)"
);
}
/// Test zero values for CompactDifficulty.
#[test]
fn compact_zero() {
zebra_test::init();
let natural_zero = CompactDifficulty(0);
assert_eq!(natural_zero.to_expanded(), None);
assert_eq!(natural_zero.to_work(), None);
// Small value zeroes
let small_zero_1 = CompactDifficulty(1);
assert_eq!(small_zero_1.to_expanded(), None);
assert_eq!(small_zero_1.to_work(), None);
let small_zero_max = CompactDifficulty(UNSIGNED_MANTISSA_MASK);
assert_eq!(small_zero_max.to_expanded(), None);
assert_eq!(small_zero_max.to_work(), None);
// Special-cased zeroes, negative in the floating-point representation
let sc_zero = CompactDifficulty(SIGN_BIT);
assert_eq!(sc_zero.to_expanded(), None);
assert_eq!(sc_zero.to_work(), None);
let sc_zero_next = CompactDifficulty(SIGN_BIT + 1);
assert_eq!(sc_zero_next.to_expanded(), None);
assert_eq!(sc_zero_next.to_work(), None);
let sc_zero_high = CompactDifficulty((1 << PRECISION) - 1);
assert_eq!(sc_zero_high.to_expanded(), None);
assert_eq!(sc_zero_high.to_work(), None);
let sc_zero_max = CompactDifficulty(u32::MAX);
assert_eq!(sc_zero_max.to_expanded(), None);
assert_eq!(sc_zero_max.to_work(), None);
}
/// Test extreme values for CompactDifficulty.
#[test]
fn compact_extremes() {
zebra_test::init();
// Values equal to one
let expanded_one = Some(ExpandedDifficulty(U256::one()));
let work_one = None;
let canonical_one = CompactDifficulty((1 << PRECISION) + (1 << 16));
assert_eq!(canonical_one.to_expanded(), expanded_one);
assert_eq!(
canonical_one.to_expanded().unwrap().to_compact(),
canonical_one
);
assert_eq!(canonical_one.to_work(), work_one);
let another_one = CompactDifficulty(OFFSET as u32 * (1 << PRECISION) + 1);
assert_eq!(another_one.to_expanded(), expanded_one);
assert_eq!(
another_one.to_expanded().unwrap().to_compact(),
canonical_one
);
assert_eq!(another_one.to_work(), work_one);
// Maximum mantissa
let expanded_mant = Some(ExpandedDifficulty(UNSIGNED_MANTISSA_MASK.into()));
let work_mant = None;
let mant = CompactDifficulty(OFFSET as u32 * (1 << PRECISION) + UNSIGNED_MANTISSA_MASK);
assert_eq!(mant.to_expanded(), expanded_mant);
assert_eq!(mant.to_expanded().unwrap().to_compact(), mant);
assert_eq!(mant.to_work(), work_mant);
// Maximum valid exponent
let exponent: U256 = (31 * 8).into();
let u256_exp = U256::from(2).pow(exponent);
let expanded_exp = Some(ExpandedDifficulty(u256_exp));
let work_exp = Some(Work(
((U256::MAX - u256_exp) / (u256_exp + 1) + 1).as_u128(),
));
let canonical_exp =
CompactDifficulty(((31 + OFFSET - 2) as u32) * (1 << PRECISION) + (1 << 16));
let another_exp = CompactDifficulty((31 + OFFSET as u32) * (1 << PRECISION) + 1);
assert_eq!(canonical_exp.to_expanded(), expanded_exp);
assert_eq!(another_exp.to_expanded(), expanded_exp);
assert_eq!(
canonical_exp.to_expanded().unwrap().to_compact(),
canonical_exp
);
assert_eq!(
another_exp.to_expanded().unwrap().to_compact(),
canonical_exp
);
assert_eq!(canonical_exp.to_work(), work_exp);
assert_eq!(another_exp.to_work(), work_exp);
// Maximum valid mantissa and exponent
let exponent: U256 = (29 * 8).into();
let u256_me = U256::from(UNSIGNED_MANTISSA_MASK) * U256::from(2).pow(exponent);
let expanded_me = Some(ExpandedDifficulty(u256_me));
let work_me = Some(Work((!u256_me / (u256_me + 1) + 1).as_u128()));
let me = CompactDifficulty((31 + 1) * (1 << PRECISION) + UNSIGNED_MANTISSA_MASK);
assert_eq!(me.to_expanded(), expanded_me);
assert_eq!(me.to_expanded().unwrap().to_compact(), me);
assert_eq!(me.to_work(), work_me);
// Maximum value, at least according to the spec
//
// According to ToTarget() in the spec, this value is
// `(2^23 - 1) * 256^253`, which is larger than the maximum expanded
// value. Therefore, a block can never pass with this threshold.
//
// zcashd rejects these blocks without comparing the hash.
let difficulty_max = CompactDifficulty(u32::MAX & !SIGN_BIT);
assert_eq!(difficulty_max.to_expanded(), None);
assert_eq!(difficulty_max.to_work(), None);
// Bitcoin test vectors for CompactDifficulty
// See https://developer.bitcoin.org/reference/block_chain.html#target-nbits
// These values are not in the table below, because they do not fit in u128
//
// The minimum difficulty on the bitcoin mainnet and testnet
let difficulty_btc_main = CompactDifficulty(0x1d00ffff);
let u256_btc_main = U256::from(0xffff) << 208;
let expanded_btc_main = Some(ExpandedDifficulty(u256_btc_main));
let work_btc_main = Some(Work(0x100010001));
assert_eq!(difficulty_btc_main.to_expanded(), expanded_btc_main);
assert_eq!(
difficulty_btc_main.to_expanded().unwrap().to_compact(),
difficulty_btc_main
);
assert_eq!(difficulty_btc_main.to_work(), work_btc_main);
// The minimum difficulty in bitcoin regtest
// This is also the easiest respesentable difficulty
let difficulty_btc_reg = CompactDifficulty(0x207fffff);
let u256_btc_reg = U256::from(0x7fffff) << 232;
let expanded_btc_reg = Some(ExpandedDifficulty(u256_btc_reg));
let work_btc_reg = Some(Work(0x2));
assert_eq!(difficulty_btc_reg.to_expanded(), expanded_btc_reg);
assert_eq!(
difficulty_btc_reg.to_expanded().unwrap().to_compact(),
difficulty_btc_reg
);
assert_eq!(difficulty_btc_reg.to_work(), work_btc_reg);
}
/// Bitcoin test vectors for CompactDifficulty, and their corresponding
/// ExpandedDifficulty and Work values.
/// See https://developer.bitcoin.org/reference/block_chain.html#target-nbits
static COMPACT_DIFFICULTY_CASES: &[(u32, Option<u128>, Option<u128>)] = &[
// These Work values will never happen in practice, because the corresponding
// difficulties are extremely high. So it is ok for us to reject them.
(0x01003456, None /* 0x00 */, None),
(0x01123456, Some(0x12), None),
(0x02008000, Some(0x80), None),
(0x05009234, Some(0x92340000), None),
(0x04923456, None /* -0x12345600 */, None),
(0x04123456, Some(0x12345600), None),
];
/// Test Bitcoin test vectors for CompactDifficulty.
#[test]
#[spandoc::spandoc]
fn compact_bitcoin_test_vectors() {
zebra_test::init();
// We use two spans, so we can diagnose conversion panics, and mismatching results
for (compact, expected_expanded, expected_work) in COMPACT_DIFFICULTY_CASES.iter().cloned() {
/// SPANDOC: Convert compact to expanded and work {?compact, ?expected_expanded, ?expected_work}
{
let expected_expanded = expected_expanded.map(U256::from).map(ExpandedDifficulty);
let expected_work = expected_work.map(Work);
let compact = CompactDifficulty(compact);
let actual_expanded = compact.to_expanded();
let actual_work = compact.to_work();
let canonical_compact = actual_expanded.map(|e| e.to_compact());
let round_trip_expanded = canonical_compact.map(|c| c.to_expanded());
/// SPANDOC: Test that compact produces the expected expanded and work {?compact, ?expected_expanded, ?actual_expanded, ?expected_work, ?actual_work, ?canonical_compact, ?round_trip_expanded}
{
assert_eq!(actual_expanded, expected_expanded);
if expected_expanded.is_some() {
assert_eq!(round_trip_expanded.unwrap(), actual_expanded);
}
assert_eq!(actual_work, expected_work);
}
}
}
}
/// Test blocks using CompactDifficulty.
#[test]
#[spandoc::spandoc]
fn block_difficulty() -> Result<(), Report> {
zebra_test::init();
let mut blockchain = Vec::new();
for b in zebra_test::vectors::BLOCKS.iter() {
let block = Arc::<Block>::zcash_deserialize(*b)?;
let hash = block.hash();
blockchain.push((block.clone(), block.coinbase_height().unwrap(), hash));
}
let diff_zero = ExpandedDifficulty(U256::zero());
let diff_one = ExpandedDifficulty(U256::one());
let diff_max = ExpandedDifficulty(U256::MAX);
let work_zero = PartialCumulativeWork(0);
let work_max = PartialCumulativeWork(u128::MAX);
let mut cumulative_work = PartialCumulativeWork::default();
let mut previous_cumulative_work = PartialCumulativeWork::default();
for (block, height, hash) in blockchain {
/// SPANDOC: Calculate the threshold for block {?height}
let threshold = block
.header
.difficulty_threshold
.to_expanded()
.expect("Chain blocks have valid difficulty thresholds.");
/// SPANDOC: Check the difficulty for block {?height, ?threshold, ?hash}
{
assert!(hash <= threshold);
// also check the comparison operators work
assert!(hash > diff_zero);
assert!(hash > diff_one);
assert!(hash < diff_max);
}
/// SPANDOC: Check compact round-trip for block {?height}
{
let canonical_compact = threshold.to_compact();
assert_eq!(block.header.difficulty_threshold,
canonical_compact);
}
/// SPANDOC: Check the work for block {?height}
{
let work = block
.header
.difficulty_threshold
.to_work()
.expect("Chain blocks have valid work.");
// also check the comparison operators work
assert!(PartialCumulativeWork::from(work) > work_zero);
assert!(PartialCumulativeWork::from(work) < work_max);
cumulative_work += work;
assert!(cumulative_work > work_zero);
assert!(cumulative_work < work_max);
assert!(cumulative_work > previous_cumulative_work);
previous_cumulative_work = cumulative_work;
}
}
Ok(())
}
/// Test ExpandedDifficulty ordering
#[test]
#[spandoc::spandoc]
#[allow(clippy::eq_op)]
fn expanded_order() -> Result<(), Report> {
zebra_test::init();
let zero = ExpandedDifficulty(U256::zero());
let one = ExpandedDifficulty(U256::one());
let max_value = ExpandedDifficulty(U256::MAX);
assert!(zero < one);
assert!(zero < max_value);
assert!(one < max_value);
assert_eq!(zero, zero);
assert!(zero <= one);
assert!(one >= zero);
assert!(one > zero);
Ok(())
}
/// Test ExpandedDifficulty and block::Hash ordering
#[test]
#[spandoc::spandoc]
fn expanded_hash_order() -> Result<(), Report> {
zebra_test::init();
let ex_zero = ExpandedDifficulty(U256::zero());
let ex_one = ExpandedDifficulty(U256::one());
let ex_max = ExpandedDifficulty(U256::MAX);
let hash_zero = block::Hash([0; 32]);
let hash_max = block::Hash([0xff; 32]);
assert_eq!(hash_zero, ex_zero);
assert!(hash_zero < ex_one);
assert!(hash_zero < ex_max);
assert!(hash_max > ex_zero);
assert!(hash_max > ex_one);
assert_eq!(hash_max, ex_max);
assert!(ex_one > hash_zero);
assert!(ex_one < hash_max);
assert!(hash_zero >= ex_zero);
assert!(ex_zero >= hash_zero);
assert!(hash_zero <= ex_zero);
assert!(ex_zero <= hash_zero);
Ok(())
}

4
zebra-consensus/src/block/tests.rs
View File

@ -15,7 +15,7 @@ use zebra_chain::{
block::{self, Block, Height}, block::{self, Block, Height},
parameters::{Network, NetworkUpgrade}, parameters::{Network, NetworkUpgrade},
serialization::{ZcashDeserialize, ZcashDeserializeInto}, serialization::{ZcashDeserialize, ZcashDeserializeInto},
work::difficulty::{CompactDifficulty, ExpandedDifficulty}, work::difficulty::{ExpandedDifficulty, INVALID_COMPACT_DIFFICULTY},
}; };
use zebra_test::transcript::{TransError, Transcript}; use zebra_test::transcript::{TransError, Transcript};
@ -188,7 +188,7 @@ fn difficulty_validation_failure() -> Result<(), Report> {
let hash = block.hash(); let hash = block.hash();
// Set the difficulty field to an invalid value // Set the difficulty field to an invalid value
block.header.difficulty_threshold = CompactDifficulty(u32::MAX); block.header.difficulty_threshold = INVALID_COMPACT_DIFFICULTY;
// Validate the block // Validate the block
let result = let result =