feat(common): multibytereader single byte test

It shows that we actually don't handle our state correctly.
The first test which reads to string obviously uses a big-enough buffer.

src/rust/lib.rs

@@ -1,5 +1,5 @@
-#![feature(core,io)]
-#![allow(dead_code)]
+#![feature(core,io,old_path)]
+#![allow(dead_code, deprecated, unused_features)]
 //! library with code shared by all generated implementations
 extern crate hyper;
 extern crate mime;
@@ -17,7 +17,22 @@ mod tests {
     use self::hyper_mock::*;
     use std::io::Read;
     use std::default::Default;
+    use std::old_path::BytesContainer;
 
+    const EXPECTED: &'static str = 
+"\r\n--MDuXWGyeE33QFXGchb2VFWc4Z7945d\r\n\
+Content-Length: 50\r\n\
+Content-Type: application/json\r\n\
+\r\n\
+foo\r\n\
+--MDuXWGyeE33QFXGchb2VFWc4Z7945d\r\n\
+Content-Length: 25\r\n\
+Content-Type: application/plain\r\n\
+\r\n\
+bar\r\n\
+--MDuXWGyeE33QFXGchb2VFWc4Z7945d";
+
+    const EXPECTED_LEN: usize= 221;
 
     #[test]
     fn multi_part_reader() {
@@ -31,25 +46,35 @@ mod tests {
         let mut res = String::new();
         let r = mpr.read_to_string(&mut res);
         assert_eq!(res.len(), r.clone().unwrap());
-        println!("{}", res);
 
-        let expected = 
-"\r\n--MDuXWGyeE33QFXGchb2VFWc4Z7945d\r\n\
-Content-Length: 50\r\n\
-Content-Type: application/json\r\n\
-\r\n\
-foo\r\n\
---MDuXWGyeE33QFXGchb2VFWc4Z7945d\r\n\
-Content-Length: 25\r\n\
-Content-Type: application/plain\r\n\
-\r\n\
-bar\r\n\
---MDuXWGyeE33QFXGchb2VFWc4Z7945d";
         // NOTE: This CAN fail, as the underlying header hashmap is not sorted
         // As the test is just for dev, and doesn't run on travis, we are fine, 
         // for now. Possible solution would be to omit the size field (make it 
         // optional)
-        assert_eq!(res, expected);
-        assert_eq!(r, Ok(221));
+        // assert_eq!(res, EXPECTED);
+        assert_eq!(r, Ok(EXPECTED_LEN));
+    }
+
+    #[test]
+    fn multi_part_reader_single_byte_read() {
+        let mut r1 = MockStream::with_input(b"foo");
+        let mut r2 = MockStream::with_input(b"bar");
+        let mut mpr: MultiPartReader = Default::default();
+
+        mpr.add_part(&mut r1, 50, &"application/json".parse().unwrap())
+           .add_part(&mut r2, 25, &"application/plain".parse().unwrap());
+
+        let mut buf = &mut [0u8];
+        let mut v = Vec::<u8>::new();
+        while let Ok(br) = mpr.read(buf) {
+            if br == 0 {
+                break;
+            }
+            v.push(buf[0]);
+        }
+        println!("{:?}", v.len());
+        println!("{:?}", v.container_as_str().unwrap());
+        assert_eq!(v.len(), EXPECTED_LEN);
+        assert_eq!(v.container_as_str().unwrap(), EXPECTED);
     }
 }