From dfbe771e6293f5ad95d282808d30556a82280b28 Mon Sep 17 00:00:00 2001
From: Sander Bosma <sanderbosma@gmail.com>
Date: Fri, 19 Aug 2022 10:08:54 +0200
Subject: [PATCH] move, document and test the FeeRate struct

---
 integration_test/src/main.rs | 17 ++++-----
 json/src/lib.rs              | 67 ++++++++++++++++++++++++++----------
 2 files changed, 55 insertions(+), 29 deletions(-)

diff --git a/integration_test/src/main.rs b/integration_test/src/main.rs
index d2e6cf9f..7039ed45 100644
--- a/integration_test/src/main.rs
+++ b/integration_test/src/main.rs
@@ -27,8 +27,8 @@ use bitcoin::hashes::hex::{FromHex, ToHex};
 use bitcoin::hashes::Hash;
 use bitcoin::secp256k1;
 use bitcoin::{
-    Address, Amount, Network, OutPoint, PrivateKey, Script, EcdsaSighashType, SignedAmount, Transaction,
-    TxIn, TxOut, Txid, Witness,
+    Address, Amount, EcdsaSighashType, Network, OutPoint, PrivateKey, Script, SignedAmount,
+    Transaction, TxIn, TxOut, Txid, Witness,
 };
 use bitcoincore_rpc::bitcoincore_rpc_json::{
     GetBlockTemplateModes, GetBlockTemplateRules, ScanTxOutRequest,
@@ -597,8 +597,9 @@ fn test_sign_raw_transaction_with_send_raw_transaction(cl: &Client) {
         }],
     };
 
-    let res =
-        cl.sign_raw_transaction_with_key(&tx, &[sk], None, Some(EcdsaSighashType::All.into())).unwrap();
+    let res = cl
+        .sign_raw_transaction_with_key(&tx, &[sk], None, Some(EcdsaSighashType::All.into()))
+        .unwrap();
     assert!(res.complete);
     let _ = cl.send_raw_transaction(&res.transaction().unwrap()).unwrap();
 }
@@ -687,7 +688,7 @@ fn test_bump_fee(cl: &Client) {
 
     // bump with explicit fee rate
     let amount_per_vbyte = Amount::from_sat(500);
-    let new_fee_rate = json::FeeRate::new(amount_per_vbyte);
+    let new_fee_rate = json::FeeRate::per_vbyte(amount_per_vbyte);
     let options = json::BumpFeeOptions {
         fee_rate: Some(new_fee_rate),
         replaceable: Some(true),
@@ -1103,11 +1104,7 @@ fn test_add_ban(cl: &Client) {
     let res = cl.list_banned().unwrap();
     assert_eq!(res.len(), 0);
 
-    assert_error_message!(
-        cl.add_ban("INVALID_STRING", 0, false),
-        -30,
-        "Error: Invalid IP/Subnet"
-    );
+    assert_error_message!(cl.add_ban("INVALID_STRING", 0, false), -30, "Error: Invalid IP/Subnet");
 }
 
 fn test_set_network_active(cl: &Client) {
diff --git a/json/src/lib.rs b/json/src/lib.rs
index fb7be174..530d3884 100644
--- a/json/src/lib.rs
+++ b/json/src/lib.rs
@@ -35,6 +35,37 @@ use std::fmt;
 
 //TODO(stevenroose) consider using a Time type
 
+/// A representation of a fee rate. Bitcoin Core uses different units in different
+/// versions. To avoid burdening the user with using the correct unit, this struct
+/// provides an umambiguous way to represent the fee rate, and the lib will perform
+/// the necessary conversions.
+#[derive(Copy, Clone, PartialEq, Eq, Debug, Default)]
+pub struct FeeRate(Amount);
+
+impl FeeRate {
+    /// Construct FeeRate from the amount per vbyte
+    pub fn per_vbyte(amount_per_vbyte: Amount) -> Self {
+        // internal representation is amount per vbyte
+        Self(amount_per_vbyte)
+    }
+
+    /// Construct FeeRate from the amount per kilo-vbyte
+    pub fn per_kvbyte(amount_per_kvbyte: Amount) -> Self {
+        // internal representation is amount per vbyte, so divide by 1000
+        Self::per_vbyte(amount_per_kvbyte / 1000)
+    }
+
+    pub fn as_sat_per_vbyte(&self) -> f64 {
+        // multiply by the number of decimals to get sat
+        self.0.as_sat() as f64
+    }
+
+    pub fn as_btc_per_kvbyte(&self) -> f64 {
+        // divide by 10^8 to get btc/vbyte, then multiply by 10^3 to get btc/kbyte
+        self.0.as_sat() as f64 / 100_000.0
+    }
+}
+
 /// A module used for serde serialization of bytes in hexadecimal format.
 ///
 /// The module is compatible with the serde attribute.
@@ -1827,9 +1858,9 @@ impl BumpFeeOptions {
     pub fn to_serializable(&self, version: usize) -> SerializableBumpFeeOptions {
         let fee_rate = self.fee_rate.map(|x| {
             if version < 210000 {
-                x.btc_per_kvbyte()
+                x.as_btc_per_kvbyte()
             } else {
-                x.sat_per_vbyte()
+                x.as_sat_per_vbyte()
             }
         });
 
@@ -1842,23 +1873,6 @@ impl BumpFeeOptions {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug, Default)]
-pub struct FeeRate(Amount);
-
-impl FeeRate {
-    pub fn new(amount_per_vbyte: Amount) -> Self {
-        Self(amount_per_vbyte)
-    }
-    pub fn sat_per_vbyte(&self) -> f64 {
-        // multiply by the number of decimals to get sat
-        self.0.as_sat() as f64
-    }
-    pub fn btc_per_kvbyte(&self) -> f64 {
-        // divide by 10^8 to get btc/vbyte, then multiply by 10^3 to get btc/kbyte
-        self.0.as_sat() as f64 / 100_000.0
-    }
-}
-
 #[derive(Serialize, Clone, PartialEq, Debug, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct SerializableBumpFeeOptions {
@@ -2072,3 +2086,18 @@ where
     }
     Ok(Some(res))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_fee_rate_conversion() {
+        let rate_1 = FeeRate::per_kvbyte(Amount::from_sat(10_000));
+        let rate_2 = FeeRate::per_vbyte(Amount::from_sat(10));
+        assert_eq!(rate_1, rate_2);
+
+        assert_eq!(rate_1.as_sat_per_vbyte(), 10.0);
+        assert_eq!(rate_1.as_btc_per_kvbyte(), 10.0 * 1e3 / 1e8);
+    }
+}