Improving PSBT FromStr error type

src/util/psbt/mod.rs

@@ -92,13 +92,33 @@ impl PartiallySignedTransaction {
 }
 
 #[cfg(feature = "base64")]
-mod _base64encoding {
+mod display_from_str {
-    use super::{PartiallySignedTransaction, Error};
+    use super::PartiallySignedTransaction;
     use std::fmt::{Display, Formatter, self};
     use std::str::FromStr;
-    use consensus::encode;
+    use consensus::encode::{Error, self};
     use ::base64::display::Base64Display;
 
+    /// Error happening during PSBT decoding from Base64 string
+    #[derive(Debug)]
+    pub enum PsbtParseError {
+        /// Error in internal PSBT data structure
+        PsbtEncoding(Error),
+        /// Error in PSBT Base64 encoding
+        Base64Encoding(::base64::DecodeError)
+    }
+
+    impl Display for PsbtParseError {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            match self {
+                PsbtParseError::PsbtEncoding(err) => Display::fmt(err, f),
+                PsbtParseError::Base64Encoding(err) => Display::fmt(err, f),
+            }
+        }
+    }
+
+    impl ::std::error::Error for PsbtParseError { }
+
     impl Display for PartiallySignedTransaction {
         fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
             write!(f, "{}", Base64Display::with_config(&encode::serialize(self), ::base64::STANDARD))
@@ -106,13 +126,16 @@ mod _base64encoding {
     }
 
     impl FromStr for PartiallySignedTransaction {
-        type Err = Error;
+        type Err = PsbtParseError;
 
         fn from_str(s: &str) -> Result<Self, Self::Err> {
-            Ok(encode::deserialize(&::base64::decode(s).map_err(|_| Error::ConsensusEncoding)?)?)
+            let data = ::base64::decode(s).map_err(PsbtParseError::Base64Encoding)?;
+            Ok(encode::deserialize(&data).map_err(PsbtParseError::PsbtEncoding)?)
         }
     }
 }
+#[cfg(feature = "base64")]
+pub use self::display_from_str::PsbtParseError;
 
 impl Encodable for PartiallySignedTransaction {
     fn consensus_encode<S: io::Write>(
@@ -469,6 +492,7 @@ mod tests {
         #[should_panic(expected = "ConsensusEncoding")]
         fn invalid_vector_2() {
             hex_psbt!("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")
+                // This weird thing is necessary since rustc 0.29 prints out I/O error in a different format than later versions
                 .map_err(Error::from)
                 .unwrap();
         }
@@ -477,7 +501,15 @@ mod tests {
         #[test]
         #[should_panic(expected = "ConsensusEncoding")]
         fn invalid_vector_2_base64() {
-            PartiallySignedTransaction::from_str("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").unwrap();
+            use util::psbt::PsbtParseError;
+            PartiallySignedTransaction::from_str("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")
+                // This weird thing is necessary since rustc 0.29 prints out I/O error in a different format than later versions
+                .map_err(|err| match err {
+                    PsbtParseError::PsbtEncoding(err) => err,
+                    PsbtParseError::Base64Encoding(_) => panic!("PSBT Base64 decoding failed")
+                })
+                .map_err(Error::from)
+                .unwrap();
         }
 
         #[test]