add message to decoding error

Author: sanav33

src/binary.rs

@@ -1,12 +1,7 @@
-pub mod error;
-use crate::{
-    binary::error::{Error, Result},
-    spec::BinarySubtype,
-    Document,
-    RawBinaryRef,
-};
+use crate::{spec::BinarySubtype, Document, RawBinaryRef};
 use std::{
     convert::TryFrom,
+    error,
     fmt::{self, Display},
 };
 
@@ -36,7 +31,9 @@ impl Binary {
     /// `subtype` argument is `None`, the [`Binary`] constructed will default to
     /// [`BinarySubtype::Generic`].
     pub fn from_base64(input: &str, subtype: impl Into<Option<BinarySubtype>>) -> Result<Self> {
-        let bytes = base64::decode(input).map_err(|_| Error::DecodingError)?;
+        let bytes = base64::decode(input).map_err(|e| Error::DecodingError {
+            message: e.to_string(),
+        })?;
         let subtype = match subtype.into() {
             Some(s) => s,
             None => BinarySubtype::Generic,
@@ -79,3 +76,23 @@ impl Binary {
         }
     }
 }
+
+/// Possible errors that can arise during [`Binary`] construction.
+#[derive(Clone, Debug)]
+#[non_exhaustive]
+pub enum Error {
+    /// While trying to decode from base64, an error was returned.
+    DecodingError { message: String },
+}
+
+impl error::Error for Error {}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Error::DecodingError { message: m } => fmt.write_str(m),
+        }
+    }
+}
+
+pub type Result<T> = std::result::Result<T, Error>;