remove nom from the error type (#52)

src/error.rs

@@ -3,9 +3,12 @@ use std::{num::TryFromIntError, string::FromUtf8Error};
 /// An Error while parsing Matroska/WebM files
 #[derive(Debug, PartialEq, thiserror::Error)]
 pub enum Error {
+    /// Need data
+    #[error("need data")]
+    NeedData,
     /// Parsing error
-    #[error("parsing error")]
-    Parsing(#[from] nom::Err<()>),
+    #[error("parser error")]
+    Parser,
     /// Invalid ID
     #[error("invalid id")]
     InvalidId,
@@ -17,7 +20,7 @@ pub enum Error {
     ForbiddenUnknownSize,
     /// Error building UTF-8 string
     #[error("{0}")]
-    Utf8Error(#[from] FromUtf8Error),
+    Utf8(#[from] FromUtf8Error),
     /// Forbidden Integer size
     #[error("forbidden integer size")]
     ForbiddenIntegerSize,
@@ -37,3 +40,24 @@ pub enum Error {
     #[error("invalid date")]
     InvalidDate,
 }
+
+impl From<nom::Err<()>> for Error {
+    fn from(value: nom::Err<()>) -> Self {
+        match value {
+            nom::Err::Incomplete(_) => Self::NeedData,
+            _ => Self::Parser,
+        }
+    }
+}
+
+// FIXME(#53) This is mostly to keep coverage happy, but that error type will
+// in practice never be instantiated as we don't use combinators in nom.
+// After removing nom as a dependency we should be able to remove this test as well.
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn parser() {
+        assert_eq!(Error::Parser, nom::Err::Error(()).into());
+    }
+}

src/lib.rs

@@ -563,12 +563,7 @@ mod tests {
         assert_eq!(parse_id(&[0x23, 0x83, 0xE3]), Ok((EMPTY, Id::FrameRate)));
 
         // 1 byte missing from FrameRate (3-bytes long)
-        assert_eq!(
-            parse_id(&[0x23, 0x83]),
-            Err(Error::Parsing(nom::Err::Incomplete(nom::Needed::Size(
-                1.try_into().unwrap()
-            ))))
-        );
+        assert_eq!(parse_id(&[0x23, 0x83]), Err(Error::NeedData));
 
         // Longer than 4 bytes
         const FAILURE_INPUT: &[u8] = &[0x08, 0x45, 0xDF, 0xA3];

tests/insta.rs

@@ -17,11 +17,12 @@ fn parse_elements(input: &[u8], show_position: bool) -> Vec<Element> {
             }
         });
         elements.push(element);
-        if new_read_buffer.is_empty() {
+        read_buffer = new_read_buffer;
+        if read_buffer.is_empty() {
             break;
         }
-        read_buffer = new_read_buffer;
     }
+    assert_eq!(read_buffer.len(), 0);
     elements
 }