Merge rust-bitcoin#2221: Implement LowerHex and UpperHex for CompactTarget

58710df Implement LowerHex and UpperHex for CompactTarget (Vojtěch Toman)

Pull request description:

  closes rust-bitcoin#2219

ACKs for top commit:
  Kixunil:
    ACK 58710df
  apoelstra:
    ACK 58710df

Tree-SHA512: 38d8bd6573f0f033f5f0948062174f7a49db02d788a5176375a869633984451651bc738cd0588d5c6e4515f521257899bdf9f61fd4be350d80a26a96f16b19b1

Author: apoelstra

bitcoin/src/pow.rs

@@ -306,6 +306,16 @@ impl Decodable for CompactTarget {
     }
 }
 
+impl LowerHex for CompactTarget {
+    #[inline]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { LowerHex::fmt(&self.0, f) }
+}
+
+impl UpperHex for CompactTarget {
+    #[inline]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { UpperHex::fmt(&self.0, f) }
+}
+
 /// Big-endian 256 bit integer type.
 // (high, low): u.0 contains the high bits, u.1 contains the low bits.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
@@ -1536,6 +1546,12 @@ mod tests {
         assert!(result.is_err());
     }
 
+    #[test]
+    fn compact_target_lower_hex_and_upper_hex() {
+        assert_eq!(format!("{:08x}", CompactTarget(0x01D0F456)), "01d0f456");
+        assert_eq!(format!("{:08X}", CompactTarget(0x01d0f456)), "01D0F456");
+    }
+
     #[test]
     fn target_from_compact() {
         // (nBits, target)