Add tests and implement correct io::Error mapping

Author: rnestler

src/serial.rs

@@ -1,6 +1,6 @@
 //! Implementation of [`Serial`](https://docs.rs/embedded-hal/0.2.1/embedded_hal/serial/index.html)
 
-use std::io::{Error as IoError, Read, Write};
+use std::io::{ErrorKind as IoErrorKind, Read, Write};
 
 use nb;
 
@@ -11,15 +11,22 @@ use serial_unix::TTYPort;
 /// the `embedded-hal` traits.
 pub struct Serial(pub TTYPort);
 
+/// Helper to convert std::io::Error to the nb::Error
+fn translate_io_errors(err: std::io::Error) -> nb::Error<IoErrorKind> {
+    match err.kind() {
+        IoErrorKind::WouldBlock | IoErrorKind::TimedOut | IoErrorKind::Interrupted => {
+            nb::Error::WouldBlock
+        }
+        err => nb::Error::Other(err),
+    }
+}
+
 impl hal::serial::Read<u8> for Serial {
-    type Error = IoError;
+    type Error = IoErrorKind;
 
     fn read(&mut self) -> nb::Result<u8, Self::Error> {
         let mut buffer = [0; 1];
-        let bytes_read = self
-            .0
-            .read(&mut buffer)
-            .map_err(|err| nb::Error::Other(Self::Error::from(err)))?;
+        let bytes_read = self.0.read(&mut buffer).map_err(translate_io_errors)?;
         if bytes_read == 1 {
             Ok(buffer[0])
         } else {
@@ -29,39 +36,54 @@ impl hal::serial::Read<u8> for Serial {
 }
 
 impl hal::serial::Write<u8> for Serial {
-    type Error = IoError;
+    type Error = IoErrorKind;
 
     fn write(&mut self, word: u8) -> nb::Result<(), Self::Error> {
-        self.0
-            .write(&[word])
-            .map_err(|err| nb::Error::Other(Self::Error::from(err)))?;
+        self.0.write(&[word]).map_err(translate_io_errors)?;
         Ok(())
     }
 
     fn flush(&mut self) -> nb::Result<(), Self::Error> {
-        self.0
-            .flush()
-            .map_err(|err| nb::Error::Other(Self::Error::from(err)))
+        self.0.flush().map_err(translate_io_errors)
     }
 }
 
 #[cfg(test)]
 mod test {
     use std::path::Path;
 
-    use hal::serial::Read;
-    use std::io::Write;
+    use hal::serial::{Read, Write};
+    use std::io::{Read as IoRead, Write as IoWrite};
 
     use super::*;
 
-    #[test]
-    fn test_empty() {
-        let (mut master, _slave, name) =
+    fn create_pty_and_serial() -> (std::fs::File, Serial) {
+        let (master, _slave, name) =
             openpty::openpty(None, None, None).expect("Creating pty failed");
-        println!("{:?}", name);
-        let port = TTYPort::open(Path::new(&name)).unwrap();
-        let mut serial = Serial(port);
-        master.write(&[1]).unwrap();
-        serial.read().unwrap();
+        let port = TTYPort::open(Path::new(&name)).expect("Creating TTYPort failed");
+        let serial = Serial(port);
+        (master, serial)
+    }
+
+    #[test]
+    fn test_empty_read() {
+        let (mut _master, mut serial) = create_pty_and_serial();
+        assert_eq!(Err(nb::Error::WouldBlock), serial.read());
+    }
+
+    #[test]
+    fn test_read() {
+        let (mut master, mut serial) = create_pty_and_serial();
+        master.write(&[1]).expect("Write failed");
+        assert_eq!(Ok(1), serial.read());
+    }
+
+    #[test]
+    fn test_write() {
+        let (mut master, mut serial) = create_pty_and_serial();
+        serial.write(2).expect("Write failed");
+        let mut buf = [0; 2];
+        assert_eq!(1, master.read(&mut buf).unwrap());
+        assert_eq!(buf, [2, 0]);
     }
 }