Added tests and implementation for I32(float) for Exercise: Protobuf …

…Parsing (google#2302)

Update for Exercise: Protobuf Parsing

* Include tests in the solution
* Remove implementatinon of wire type I32, but leave it as a "more-to-explore" extension

src/lifetimes/exercise.md

@@ -56,7 +56,9 @@ What remains for you is to implement the `parse_field` function and the
 
 {{#include exercise.rs:parse_message }}
 
-{{#include exercise.rs:message_types}}
+{{#include exercise.rs:message_phone_number_type}}
+
+{{#include exercise.rs:message_person_type}}
 
 // TODO: Implement ProtoMessage for Person and PhoneNumber.
 

src/lifetimes/exercise.rs

@@ -18,13 +18,15 @@
 enum WireType {
     /// The Varint WireType indicates the value is a single VARINT.
     Varint,
+    /// The I64 WireType indicates that the value is precisely 8 bytes in
+    /// little-endian order containing a 64-bit signed integer or double type.
     //I64,  -- not needed for this exercise
     /// The Len WireType indicates that the value is a length represented as a
     /// VARINT followed by exactly that number of bytes.
     Len,
-    /// The I32 WireType indicates that the value is precisely 4 bytes in
-    /// little-endian order containing a 32-bit signed integer.
-    I32,
+    // The I32 WireType indicates that the value is precisely 4 bytes in
+    // little-endian order containing a 32-bit signed integer or float type.
+    //I32,  -- not needed for this exercise
 }
 
 #[derive(Debug)]
@@ -33,7 +35,7 @@ enum FieldValue<'a> {
     Varint(u64),
     //I64(i64),  -- not needed for this exercise
     Len(&'a [u8]),
-    I32(i32),
+    //I32(i32),  -- not needed for this exercise
 }
 
 #[derive(Debug)]
@@ -53,7 +55,7 @@ impl From<u64> for WireType {
             0 => WireType::Varint,
             //1 => WireType::I64,  -- not needed for this exercise
             2 => WireType::Len,
-            5 => WireType::I32,
+            //5 => WireType::I32,  -- not needed for this exercise
             _ => panic!("Invalid wire type: {value}"),
         }
     }
@@ -80,14 +82,6 @@ impl<'a> FieldValue<'a> {
         };
         *value
     }
-
-    #[allow(dead_code)]
-    fn as_i32(&self) -> i32 {
-        let FieldValue::I32(value) = self else {
-            panic!("Expected `i32` to be an `I32` field");
-        };
-        *value
-    }
 }
 
 /// Parse a VARINT, returning the parsed value and the remaining bytes.
@@ -139,15 +133,6 @@ fn parse_field(data: &[u8]) -> (Field, &[u8]) {
             let (value, remainder) = remainder.split_at(len);
             (FieldValue::Len(value), remainder)
         }
-        WireType::I32 => {
-            if remainder.len() < 4 {
-                panic!("Unexpected EOF");
-            }
-            let (value, remainder) = remainder.split_at(4);
-            // Unwrap error because `value` is definitely 4 bytes long.
-            let value = i32::from_le_bytes(value.try_into().unwrap());
-            (FieldValue::I32(value), remainder)
-        }
     };
     (Field { field_num, value: fieldvalue }, remainder)
 }
@@ -168,20 +153,24 @@ fn parse_message<'a, T: ProtoMessage<'a>>(mut data: &'a [u8]) -> T {
 }
 // ANCHOR_END: parse_message
 
-// ANCHOR: message_types
+#[derive(PartialEq)]
+// ANCHOR: message_message_phone_number_type
 #[derive(Debug, Default)]
 struct PhoneNumber<'a> {
     number: &'a str,
     type_: &'a str,
 }
+// ANCHOR_END: message_phone_number_type
 
+#[derive(PartialEq)]
+// ANCHOR: message_person_type
 #[derive(Debug, Default)]
 struct Person<'a> {
     name: &'a str,
     id: u64,
     phone: Vec<PhoneNumber<'a>>,
 }
-// ANCHOR_END: message_types
+// ANCHOR_END: message_person_type
 
 impl<'a> ProtoMessage<'a> for Person<'a> {
     fn add_field(&mut self, field: Field<'a>) {
@@ -217,3 +206,50 @@ fn main() {
     println!("{:#?}", person);
 }
 // ANCHOR_END: main
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_id() {
+        let person_id: Person = parse_message(&[0x10, 0x2a]);
+        assert_eq!(person_id, Person { name: "", id: 42, phone: vec![] });
+    }
+
+    #[test]
+    fn test_name() {
+        let person_name: Person = parse_message(&[
+            0x0a, 0x0e, 0x62, 0x65, 0x61, 0x75, 0x74, 0x69, 0x66, 0x75, 0x6c, 0x20,
+            0x6e, 0x61, 0x6d, 0x65,
+        ]);
+        assert_eq!(
+            person_name,
+            Person { name: "beautiful name", id: 0, phone: vec![] }
+        );
+    }
+
+    #[test]
+    fn test_just_person() {
+        let person_name_id: Person =
+            parse_message(&[0x0a, 0x04, 0x45, 0x76, 0x61, 0x6e, 0x10, 0x16]);
+        assert_eq!(person_name_id, Person { name: "Evan", id: 22, phone: vec![] });
+    }
+
+    #[test]
+    fn test_phone() {
+        let phone: Person = parse_message(&[
+            0x0a, 0x00, 0x10, 0x00, 0x1a, 0x16, 0x0a, 0x0e, 0x2b, 0x31, 0x32, 0x33,
+            0x34, 0x2d, 0x37, 0x37, 0x37, 0x2d, 0x39, 0x30, 0x39, 0x30, 0x12, 0x04,
+            0x68, 0x6f, 0x6d, 0x65,
+        ]);
+        assert_eq!(
+            phone,
+            Person {
+                name: "",
+                id: 0,
+                phone: vec![PhoneNumber { number: "+1234-777-9090", type_: "home" },],
+            }
+        );
+    }
+}