Tests for the codec

Author: vorner

src/codec.rs

@@ -25,7 +25,10 @@ impl TokioCodec for Codec {
     type In = Message;
     type Out = Message;
     fn decode(&mut self, buf: &mut EasyBuf) -> IoResult<Option<Message>> {
-        // TODO: Use object boundary instead of newlines
+        // TODO: Use object boundary instead of newlines. This waits for
+        // https://github.com/serde-rs/json/pull/212 or for being able to
+        // distinguish EOF errors from the others for the trick in
+        // https://github.com/serde-rs/json/issues/183.
         if let Some(i) = buf.as_slice().iter().position(|&b| b == b'\n') {
             let line = buf.drain_to(i);
             buf.drain_to(1);
@@ -40,3 +43,51 @@ impl TokioCodec for Codec {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn encode() {
+        let mut output = Vec::new();
+        let mut codec = Codec;
+        codec.encode(Message::notification("notif".to_owned(), None), &mut output).unwrap();
+        assert_eq!(Vec::from(&b"{\"jsonrpc\":\"2.0\",\"method\":\"notif\"}\n"[..]), output);
+    }
+
+    #[test]
+    fn decode() {
+        fn one(input: &[u8], rest: &[u8]) -> IoResult<Option<Message>> {
+            let mut codec = Codec;
+            let mut buf = EasyBuf::new();
+            buf.get_mut().extend_from_slice(input);
+            let result = codec.decode(&mut buf);
+            assert_eq!(rest, buf.as_slice());
+            result
+        }
+
+        // TODO: We currently have to terminate the records by newline, but that's a temporary
+        // problem. Once that is solved, have some tests without the newline as well. Also, test
+        // some messages that don't have a newline, but have a syntax error, so we know we abort
+        // soon enough.
+
+        let notif = Message::notification("notif".to_owned(), None);
+        let msgstring = Vec::from(&b"{\"jsonrpc\":\"2.0\",\"method\":\"notif\"}\n"[..]);
+        // A single message, nothing is left
+        assert_eq!(one(&msgstring, b"").unwrap(), Some(notif.clone()));
+        // The first message is decoded, the second stays in the buffer
+        let mut twomsgs = msgstring.clone();
+        twomsgs.extend_from_slice(&msgstring);
+        assert_eq!(one(&twomsgs, &msgstring).unwrap(), Some(notif.clone()));
+        // The second message is incomplete, but stays there
+        let incomplete = Vec::from(&br#"{"jsonrpc": "2.0", "method":""#[..]);
+        let mut oneandhalf = msgstring.clone();
+        oneandhalf.extend_from_slice(&incomplete);
+        assert_eq!(one(&oneandhalf, &incomplete).unwrap(), Some(notif.clone()));
+        // An incomplete message ‒ nothing gets out and everything stays
+        assert_eq!(one(&incomplete, &incomplete).unwrap(), None);
+        // A syntax error is reported as an error (and eaten, but that's no longer interesting)
+        assert!(one(b"{]\n", b"").is_err());
+    }
+}