From 0cf6da4f03be11ed303cda7fdb95538c491a3305 Mon Sep 17 00:00:00 2001
From: bnabi <bnabi@protonmail.com>
Date: Thu, 12 Jan 2023 12:28:02 +0530
Subject: [PATCH] amount parses 0 msats

---
 bitcoin/src/amount.rs | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/bitcoin/src/amount.rs b/bitcoin/src/amount.rs
index 23f9345f..8c5dc446 100644
--- a/bitcoin/src/amount.rs
+++ b/bitcoin/src/amount.rs
@@ -253,7 +253,10 @@ fn parse_signed_to_satoshi(
             // many as the difference in precision.
             let last_n = unsigned_abs(precision_diff).into();
             if is_too_precise(s, last_n) {
-                return Err(ParseAmountError::TooPrecise);
+                match s.parse::<i64>() {
+                    Ok(v) if v == 0_i64 => return Ok((is_negative, 0)),
+                    _ => return Err(ParseAmountError::TooPrecise),
+                }
             }
             s = &s[0..s.len() - last_n];
             0
@@ -1545,6 +1548,30 @@ mod tests {
 
     use super::*;
 
+    #[test]
+    fn from_str_zero() {
+        let denoms = vec!["BTC", "mBTC", "uBTC", "nBTC", "pBTC", "bits", "sats", "msats"];
+        for denom in denoms {
+            for v in &["0", "000"] {
+                let s = format!("{} {}", v, denom);
+                match Amount::from_str(&s) {
+                    Err(e) => panic!("Failed to crate amount from {}: {:?}", s, e),
+                    Ok(amount) => assert_eq!(amount, Amount::from_sat(0)),
+                }
+            }
+
+            let s = format!("-0 {}", denom);
+            match Amount::from_str(&s) {
+                Err(e) => assert_eq!(e, ParseAmountError::Negative),
+                Ok(_) => panic!("Unsigned amount from {}", s),
+            }
+            match SignedAmount::from_str(&s) {
+                Err(e) => panic!("Failed to crate amount from {}: {:?}", s, e),
+                Ok(amount) => assert_eq!(amount, SignedAmount::from_sat(0)),
+            }
+        }
+    }
+
     #[test]
     fn mul_div() {
         let sat = Amount::from_sat;
@@ -1939,15 +1966,6 @@ mod tests {
         scase("-200000000000 BTC", Err(E::TooBig));
         case("18446744073709551616 sat", Err(E::TooBig));
 
-        scase("0 msat", Err(E::TooPrecise));
-        scase("-0 msat", Err(E::TooPrecise));
-        scase("000 msat", Err(E::TooPrecise));
-        scase("-000 msat", Err(E::TooPrecise));
-        case("0 msat", Err(E::TooPrecise));
-        case("-0 msat", Err(E::TooPrecise));
-        case("000 msat", Err(E::TooPrecise));
-        case("-000 msat", Err(E::TooPrecise));
-
         case(".5 bits", Ok(Amount::from_sat(50)));
         scase("-.5 bits", Ok(SignedAmount::from_sat(-50)));
         case("0.00253583 BTC", Ok(Amount::from_sat(253583)));