add a funding_stream_address_change_interval method

zebra-chain/src/parameters/network/subsidy.rs

@@ -392,6 +392,9 @@ pub trait ParameterSubsidy {
 
     /// Returns the halving interval before Blossom
     fn pre_blossom_halving_interval(&self) -> HeightDiff;
+
+    /// Returns the address change interval for funding streams
+    fn funding_stream_address_change_interval(&self) -> HeightDiff;
 }
 
 /// Network methods related to Block Subsidy and Funding Streams
@@ -427,6 +430,10 @@ impl ParameterSubsidy for Network {
             Network::Testnet(params) => params.pre_blossom_halving_interval(),
         }
     }
+
+    fn funding_stream_address_change_interval(&self) -> HeightDiff {
+        self.post_blossom_halving_interval() / 48
+    }
 }
 
 /// List of addresses for the Zcash Foundation funding stream in the Mainnet.
@@ -536,7 +543,7 @@ pub fn funding_stream_address_period<N: ParameterSubsidy>(height: Height, networ
     let height_after_first_halving = height - network.height_for_first_halving();
 
     let address_period = (height_after_first_halving + network.post_blossom_halving_interval())
-        / FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL;
+        / network.funding_stream_address_change_interval();
 
     address_period
         .try_into()

zebra-chain/src/parameters/network/testnet.rs

@@ -16,7 +16,8 @@ use super::{
     magic::Magic,
     subsidy::{
         FundingStreamReceiver, FundingStreamRecipient, FundingStreams, ParameterSubsidy,
-        FIRST_HALVING_TESTNET, POST_BLOSSOM_HALVING_INTERVAL, POST_NU6_FUNDING_STREAMS_MAINNET,
+        FIRST_HALVING_TESTNET, FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL,
+        POST_BLOSSOM_HALVING_INTERVAL, POST_NU6_FUNDING_STREAMS_MAINNET,
         POST_NU6_FUNDING_STREAMS_TESTNET, PRE_BLOSSOM_HALVING_INTERVAL,
         PRE_BLOSSOM_REGTEST_HALVING_INTERVAL, PRE_NU6_FUNDING_STREAMS_MAINNET,
         PRE_NU6_FUNDING_STREAMS_TESTNET,
@@ -66,6 +67,10 @@ impl ParameterSubsidy for TestnetParameterSubsidyImpl {
     fn pre_blossom_halving_interval(&self) -> block::HeightDiff {
         PRE_BLOSSOM_HALVING_INTERVAL
     }
+
+    fn funding_stream_address_change_interval(&self) -> HeightDiff {
+        FUNDING_STREAM_ADDRESS_CHANGE_INTERVAL
+    }
 }
 
 /// Configurable funding stream recipient for configured Testnets.