Remove duplicate and redundant consensus parameter code (#4760)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

zebra-consensus/src/lib.rs

@@ -37,7 +37,6 @@
 mod block;
 mod checkpoint;
 mod config;
-#[allow(dead_code)]
 mod parameters;
 mod primitives;
 mod script;

zebra-consensus/src/parameters.rs

@@ -12,11 +12,6 @@
 //! Typically, consensus parameters are accessed via a function that takes a
 //! `Network` and `block::Height`.
 
-pub mod minimum_difficulty;
 pub mod subsidy;
 
-pub use minimum_difficulty::*;
 pub use subsidy::*;
-
-#[cfg(test)]
-mod tests;

zebra-consensus/src/parameters/minimum_difficulty.rs

@@ -1,39 +0,0 @@
-//! The minimum difficulty block rule for Zcash.
-
-use zebra_chain::{block, parameters::Network};
-
-/// The testnet block height when minimum difficulty blocks start being
-/// accepted.
-pub(crate) const TESTNET_MINIMUM_DIFFICULTY_HEIGHT: block::Height = block::Height(299_188);
-
-/// The Zcash Testnet consensus rules were changed to allow
-/// minimum-difficulty blocks, shortly after Testnet Sapling activation.
-/// See ZIP-205 and ZIP-208 for details.
-///
-/// This change represents a hard-fork on Testnet, but it doesn't appear on
-/// Mainnet, so we handle it as an independent consensus rule change.
-#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
-pub enum MinimumDifficulty {
-    /// Minimum difficulty blocks are rejected.
-    ///
-    /// Always returned for Mainnet blocks.
-    Rejected,
-    /// Minimum difficulty blocks are allowed.
-    ///
-    /// Only allowed for Testnet blocks.
-    AllowedOnTestnet,
-}
-
-impl MinimumDifficulty {
-    /// Returns the current minimum difficulty rule for `network` and `height`.
-    pub fn current(network: Network, height: block::Height) -> MinimumDifficulty {
-        use MinimumDifficulty::*;
-        use Network::*;
-
-        match network {
-            Mainnet => Rejected,
-            Testnet if (height >= TESTNET_MINIMUM_DIFFICULTY_HEIGHT) => AllowedOnTestnet,
-            Testnet => Rejected,
-        }
-    }
-}

zebra-consensus/src/parameters/subsidy.rs

@@ -52,15 +52,6 @@ pub enum FundingStreamReceiver {
     MajorGrants,
 }
 
-impl FundingStreamReceiver {
-    /// Get a list of receiver types
-    pub const fn receivers() -> [Self; 3] {
-        [Self::Ecc, Self::ZcashFoundation, Self::MajorGrants]
-    }
-}
-/// The number of funding stream receiver categories.
-pub const FUNDING_STREAM_RECEIVERS_NUMBER: usize = FundingStreamReceiver::receivers().len();
-
 /// Denominator as described in [protocol specification §7.10.1][7.10.1].
 ///
 /// [7.10.1]: https://zips.z.cash/protocol/protocol.pdf#zip214fundingstreams

zebra-consensus/src/parameters/tests.rs

@@ -1,48 +0,0 @@
-//! Consensus parameter tests for Zebra.
-
-use super::*;
-
-use zebra_chain::{
-    block,
-    parameters::Network::{self, *},
-};
-
-#[test]
-fn minimum_difficulty_mainnet() {
-    minimum_difficulty(Mainnet)
-}
-
-#[test]
-fn minimum_difficulty_testnet() {
-    minimum_difficulty(Testnet)
-}
-
-/// Test MinimumDifficulty
-fn minimum_difficulty(network: Network) {
-    zebra_test::init();
-    use block::Height;
-    use MinimumDifficulty::*;
-
-    let allowed_if_testnet = match network {
-        Mainnet => Rejected,
-        Testnet => AllowedOnTestnet,
-    };
-
-    assert_eq!(MinimumDifficulty::current(network, Height(0)), Rejected);
-    assert_eq!(
-        MinimumDifficulty::current(network, Height(299_187)),
-        Rejected
-    );
-    assert_eq!(
-        MinimumDifficulty::current(network, Height(299_188)),
-        allowed_if_testnet
-    );
-    assert_eq!(
-        MinimumDifficulty::current(network, Height(299_189)),
-        allowed_if_testnet
-    );
-    assert_eq!(
-        MinimumDifficulty::current(network, Height::MAX),
-        allowed_if_testnet
-    );
-}