Coverage Report

Created: 2025-07-23 06:36

/rust/registry/src/index.crates.io-6f17d22bba15001f/der-0.7.10/src/reader/slice.rs
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//! Slice reader.
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use crate::{BytesRef, Decode, Error, ErrorKind, Header, Length, Reader, Result, Tag};
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/// [`Reader`] which consumes an input byte slice.
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#[derive(Clone, Debug)]
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pub struct SliceReader<'a> {
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    /// Byte slice being decoded.
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    bytes: BytesRef<'a>,
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    /// Did the decoding operation fail?
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    failed: bool,
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    /// Position within the decoded slice.
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    position: Length,
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}
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impl<'a> SliceReader<'a> {
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    /// Create a new slice reader for the given byte slice.
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    pub fn new(bytes: &'a [u8]) -> Result<Self> {
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        Ok(Self {
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            bytes: BytesRef::new(bytes)?,
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            failed: false,
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            position: Length::ZERO,
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        })
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    }
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    /// Return an error with the given [`ErrorKind`], annotating it with
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    /// context about where the error occurred.
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0
    pub fn error(&mut self, kind: ErrorKind) -> Error {
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        self.failed = true;
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        kind.at(self.position)
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    }
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    /// Return an error for an invalid value with the given tag.
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    pub fn value_error(&mut self, tag: Tag) -> Error {
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        self.error(tag.value_error().kind())
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    }
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    /// Did the decoding operation fail due to an error?
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    pub fn is_failed(&self) -> bool {
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        self.failed
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    }
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    /// Obtain the remaining bytes in this slice reader from the current cursor
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    /// position.
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    fn remaining(&self) -> Result<&'a [u8]> {
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        if self.is_failed() {
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            Err(ErrorKind::Failed.at(self.position))
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        } else {
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            self.bytes
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                .as_slice()
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                .get(self.position.try_into()?..)
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                .ok_or_else(|| Error::incomplete(self.input_len()))
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        }
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    }
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}
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impl<'a> Reader<'a> for SliceReader<'a> {
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    fn input_len(&self) -> Length {
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        self.bytes.len()
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    }
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    fn peek_byte(&self) -> Option<u8> {
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        self.remaining()
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            .ok()
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            .and_then(|bytes| bytes.first().cloned())
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    }
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    fn peek_header(&self) -> Result<Header> {
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        Header::decode(&mut self.clone())
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    }
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    fn position(&self) -> Length {
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        self.position
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    }
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    fn read_slice(&mut self, len: Length) -> Result<&'a [u8]> {
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        if self.is_failed() {
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            return Err(self.error(ErrorKind::Failed));
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        }
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        match self.remaining()?.get(..len.try_into()?) {
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            Some(result) => {
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                self.position = (self.position + len)?;
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                Ok(result)
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            }
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            None => Err(self.error(ErrorKind::Incomplete {
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                expected_len: (self.position + len)?,
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                actual_len: self.input_len(),
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            })),
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        }
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    }
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    fn decode<T: Decode<'a>>(&mut self) -> Result<T> {
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        if self.is_failed() {
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            return Err(self.error(ErrorKind::Failed));
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        }
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        T::decode(self).map_err(|e| {
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            self.failed = true;
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            e.nested(self.position)
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        })
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    }
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    fn error(&mut self, kind: ErrorKind) -> Error {
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        self.failed = true;
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        kind.at(self.position)
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    }
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    fn finish<T>(self, value: T) -> Result<T> {
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        if self.is_failed() {
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            Err(ErrorKind::Failed.at(self.position))
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        } else if !self.is_finished() {
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            Err(ErrorKind::TrailingData {
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                decoded: self.position,
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                remaining: self.remaining_len(),
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            }
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            .at(self.position))
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        } else {
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            Ok(value)
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        }
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    }
<der::reader::slice::SliceReader as der::reader::Reader>::finish::<(der::asn1::integer::uint::UintRef, der::asn1::integer::uint::UintRef)>
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    fn finish<T>(self, value: T) -> Result<T> {
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        if self.is_failed() {
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            Err(ErrorKind::Failed.at(self.position))
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        } else if !self.is_finished() {
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            Err(ErrorKind::TrailingData {
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                decoded: self.position,
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                remaining: self.remaining_len(),
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            }
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            .at(self.position))
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        } else {
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            Ok(value)
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        }
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    }
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<sec1::private_key::EcPrivateKey>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::document::Document>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::bit_string::BitStringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::ia5_string::Ia5StringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::utf8_string::Utf8StringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::octet_string::OctetStringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::teletex_string::TeletexStringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::videotex_string::VideotexStringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::generalized_time::GeneralizedTime>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::printable_string::PrintableStringRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::any::AnyRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::null::Null>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::utc_time::UtcTime>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::bit_string::allocating::BitString>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::ia5_string::allocation::Ia5String>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::octet_string::allocating::OctetString>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::teletex_string::allocation::TeletexString>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::printable_string::allocation::PrintableString>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::integer::int::IntRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::integer::uint::UintRef>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::integer::int::allocating::Int>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<der::asn1::integer::uint::allocating::Uint>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<i8>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<u8>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<i32>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<u32>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<i128>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<u128>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<i16>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<u16>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<()>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<i64>
Unexecuted instantiation: <der::reader::slice::SliceReader as der::reader::Reader>::finish::<u64>
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    fn remaining_len(&self) -> Length {
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        debug_assert!(self.position <= self.input_len());
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        self.input_len().saturating_sub(self.position)
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    }
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}
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#[cfg(test)]
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mod tests {
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    use super::SliceReader;
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    use crate::{Decode, ErrorKind, Length, Reader, Tag};
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    use hex_literal::hex;
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    // INTEGER: 42
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    const EXAMPLE_MSG: &[u8] = &hex!("02012A00");
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    #[test]
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    fn empty_message() {
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        let mut reader = SliceReader::new(&[]).unwrap();
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        let err = bool::decode(&mut reader).err().unwrap();
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        assert_eq!(Some(Length::ZERO), err.position());
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        match err.kind() {
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            ErrorKind::Incomplete {
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                expected_len,
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                actual_len,
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            } => {
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                assert_eq!(actual_len, 0u8.into());
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                assert_eq!(expected_len, 1u8.into());
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            }
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            other => panic!("unexpected error kind: {:?}", other),
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        }
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    }
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    #[test]
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    fn invalid_field_length() {
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        const MSG_LEN: usize = 2;
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        let mut reader = SliceReader::new(&EXAMPLE_MSG[..MSG_LEN]).unwrap();
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        let err = i8::decode(&mut reader).err().unwrap();
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        assert_eq!(Some(Length::from(2u8)), err.position());
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        match err.kind() {
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            ErrorKind::Incomplete {
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                expected_len,
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                actual_len,
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            } => {
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                assert_eq!(actual_len, MSG_LEN.try_into().unwrap());
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                assert_eq!(expected_len, (MSG_LEN + 1).try_into().unwrap());
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            }
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            other => panic!("unexpected error kind: {:?}", other),
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        }
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    }
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    #[test]
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    fn trailing_data() {
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        let mut reader = SliceReader::new(EXAMPLE_MSG).unwrap();
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        let x = i8::decode(&mut reader).unwrap();
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        assert_eq!(42i8, x);
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        let err = reader.finish(x).err().unwrap();
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        assert_eq!(Some(Length::from(3u8)), err.position());
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        assert_eq!(
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            ErrorKind::TrailingData {
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                decoded: 3u8.into(),
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                remaining: 1u8.into()
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            },
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            err.kind()
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        );
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    }
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    #[test]
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    fn peek_tag() {
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        let reader = SliceReader::new(EXAMPLE_MSG).unwrap();
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        assert_eq!(reader.position(), Length::ZERO);
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        assert_eq!(reader.peek_tag().unwrap(), Tag::Integer);
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        assert_eq!(reader.position(), Length::ZERO); // Position unchanged
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    }
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    #[test]
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    fn peek_header() {
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        let reader = SliceReader::new(EXAMPLE_MSG).unwrap();
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        assert_eq!(reader.position(), Length::ZERO);
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        let header = reader.peek_header().unwrap();
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        assert_eq!(header.tag, Tag::Integer);
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        assert_eq!(header.length, Length::ONE);
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        assert_eq!(reader.position(), Length::ZERO); // Position unchanged
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    }
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}