Added a few tests and got them working. Added feature "trace".

Cargo.toml

@@ -11,4 +11,11 @@ repository = "https://github.com/fluffysquirrels/framed"
 
 [dependencies]
 cobs = "^0.1.2"
-error-chain = "^0.11.0"
+error-chain = "^0.11.0"
+ref_slice = "^1.1.1"
+
+[features]
+default_features = []
+
+# Enable to print all data to stdout for testing.
+trace = []

src/error.rs

@@ -12,5 +12,9 @@ error_chain! {
             description("COBS decode failed"),
             display("COBS decode failed"),
         }
+        EofDuringFrame {
+            description("end of file during a frame"),
+            display("end of file during a frame"),
+        }
     }
 }

src/lib.rs

@@ -8,8 +8,19 @@
 //!
 //! [dll]: https://en.wikipedia.org/wiki/Data_link_layer
 //! [pl]: https://en.wikipedia.org/wiki/Physical_layer
-
-// TODO: Make this work when no_std.
+//!
+//! Currently the encoding is: the frame [COBS]-encoded
+//! to remove bytes equal to zero, then a terminating zero byte.
+//! [COBS]: https://en.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing
+//!
+//! ## Cargo feature flags
+//! `trace`: Enable to print all data to stdout for testing.
+//!
+//! ## TODO
+//! * Start frame with a zero as well, then we detect partial frames.
+//! * Add a length field to the beginning of the frame and a
+//!   checksum to the end. Perhaps make them optional.
+//! * Support no_std.
 
 #![deny(warnings)]
 #![feature(conservative_impl_trait)]
@@ -17,12 +28,16 @@
 extern crate cobs;
 #[macro_use]
 extern crate error_chain;
+extern crate ref_slice;
 
 pub mod channel;
 
 pub mod error;
 use error::{Error, ErrorKind, Result};
-use std::io::{Read, Write};
+use ref_slice::ref_slice_mut;
+use std::io::{self, Read, Write};
+
+const FRAME_END: u8 = 0;
 
 /// Sends frames over an underlying `io::Write` instance.
 pub struct Sender<W: Write> {
@@ -37,7 +52,11 @@ impl<W: Write> Sender<W> {
     }
 
     pub fn send(&mut self, f: &[u8]) -> Result<()> {
-        let code = cobs::encode_vec(f);
+        let mut code = cobs::encode_vec(f);
+        code.push(FRAME_END);
+        #[cfg(feature = "trace")] {
+            println!("framed: Sending code = {:?}", code);
+        }
         self.w.write(&code)?;
         Ok(())
     }
@@ -45,6 +64,7 @@ impl<W: Write> Sender<W> {
 
 /// Receives frames from an underlying `io::Read` instance.
 pub struct Receiver<R: Read> {
+    /// The underlying reader
     r: R,
 }
 
@@ -56,9 +76,35 @@ impl<R: Read> Receiver<R> {
     }
 
     pub fn recv(&mut self) -> Result<Vec<u8>> {
-        let mut code = Vec::new();
-        self.r.read_to_end(&mut code)?;
-        cobs::decode_vec(&code)
+        let mut next_frame = Vec::new();
+
+        let mut b = 0u8;
+        loop {
+            let res = self.r.read(ref_slice_mut(&mut b));
+            #[cfg(feature = "trace")] {
+                println!("framed: Read result = {:?}", res);
+            }
+            match res {
+                Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof =>
+                    return Err(Error::from(ErrorKind::EofDuringFrame)),
+                Ok(0) =>
+                    return Err(Error::from(ErrorKind::EofDuringFrame)),
+                Err(e) => return Err(Error::from(e)),
+                Ok(_) => (),
+            };
+
+            #[cfg(feature = "trace")] {
+                println!("framed: Read byte = {}", b);
+            }
+            if b == FRAME_END {
+                break;
+            } else {
+                next_frame.push(b);
+            }
+        }
+        assert!(b == FRAME_END);
+
+        cobs::decode_vec(&next_frame)
              .map_err(|_| Error::from(ErrorKind::CobsDecodeFailed))
     }
 }
@@ -66,6 +112,7 @@ impl<R: Read> Receiver<R> {
 #[cfg(test)]
 mod tests {
     use channel::Channel;
+    use error::{Error, ErrorKind};
     use std::io::{Read, Write};
     use super::{Receiver, Sender};
 
@@ -78,13 +125,50 @@ mod tests {
         assert_eq!(recvd, sent);
     }
 
-    // TODO: Test sending 2 different frames.
+    #[test]
+    fn two_frames_sequentially() {
+        let (mut tx, mut rx) = pair();
+        {
+            let sent = [0x00, 0x01, 0x02];
+            tx.send(&sent).unwrap();
+            let recvd = rx.recv().unwrap();
+            assert_eq!(recvd, sent);
+        }
 
-    // TODO: Test buffering:
-    // * Write half a frame
-    // * recv() returns nothing
-    // * Write the rest of the frame
-    // * recv() returns the whole frame
+        {
+            let sent = [0x10, 0x11, 0x12];
+            tx.send(&sent).unwrap();
+            let recvd = rx.recv().unwrap();
+            assert_eq!(recvd, sent);
+        }
+    }
+
+    #[test]
+    fn two_frames_at_once() {
+        let (mut tx, mut rx) = pair();
+        let s1 = [0x00, 0x01, 0x02];
+        let s2 = [0x10, 0x11, 0x12];
+
+        tx.send(&s1).unwrap();
+        tx.send(&s2).unwrap();
+
+        let r1 = rx.recv().unwrap();
+        let r2 = rx.recv().unwrap();
+        println!("r1: {:?}\n\
+                  r2: {:?}", r1, r2);
+
+        assert_eq!(r1, s1);
+        assert_eq!(r2, s2);
+    }
+
+    #[test]
+    fn empty_input() {
+        let (mut _tx, mut rx) = pair();
+        match rx.recv() {
+            Err(Error(ErrorKind::EofDuringFrame, _)) => (),
+            e @ _ => panic!("Bad value: {:?}", e)
+        }
+    }
 
     fn pair() -> (Sender<impl Write>, Receiver<impl Read>) {
         let c = Channel::new();