started on decode for u16

Author: simplist-coder

amqp-type/src/fixed_width/ushort.rs

@@ -1,11 +1,37 @@
 use crate::serde::encode::{Encode, Encoded};
+use crate::serde::decode::Decode;
+
+const BYTE_LEN: usize = 2;
 
 impl Encode for u16 {
     fn encode(&self) -> Encoded {
         Encoded::new_fixed(0x60, self.to_be_bytes().to_vec())
     }
 }
 
+impl Decode for u16 {
+    fn can_decode(iter: impl Iterator<Item = u8>) -> bool {
+        match iter.peekable().peek() {
+            Some(0x60) => true,
+            _ => false
+        }
+    }
+
+    fn try_decode(mut iter: impl Iterator<Item = u8>) -> Result<Self, crate::error::AppError>
+        where
+            Self: Sized {
+        let mut val_bytes = [0; BYTE_LEN];
+        let con = iter.next();
+        let mut index = 0;
+        for b in iter.take(BYTE_LEN) {
+            val_bytes[index] = b;
+            index += 1;
+        }
+        Ok(u16::from_be_bytes(val_bytes))
+    }
+}
+
+
 #[cfg(test)]
 mod test {
 
@@ -16,4 +42,23 @@ mod test {
         let val: u16 = 16;
         assert_eq!(val.encode().constructor(), 0x60);
     }
+
+    
+    #[test]
+    fn can_deocde_returns_true_if_constructor_is_valid() {
+        let val = vec![0x60, 0x41];
+        assert_eq!(u16::can_decode(val.into_iter()), true);
+    }
+
+    #[test]
+    fn can_decode_return_false_if_constructor_is_invalid() {
+        let val = vec![0x61];
+        assert_eq!(u16::can_decode(val.into_iter()), false);
+    }
+
+    #[test]
+    fn try_decode_returns_correct_value() {
+        let val = vec![0x60, 0x00, 0x10];
+        assert_eq!(u16::try_decode(val.into_iter()).unwrap(), 16)
+    }
 }