add test for eval

src/main.rs

@@ -1,4 +1,4 @@
-use std::{error::Error, io};
+use std::io;
 
 #[derive(Debug, PartialEq, Eq)]
 enum Symbol {
@@ -20,6 +20,21 @@ enum Node {
     Number { value: u64 },
 }
 
+#[test]
+fn test_eval() {
+    let node_to_eval = Node::Add {
+        left: Box::new(Node::Add {
+            left: Box::new(Node::Number { value: 1 }),
+            right: Box::new(Node::Number { value: 1 }),
+        }),
+        right: Box::new(Node::Number { value: 3 }),
+    };
+
+    let result = eval(&node_to_eval);
+
+    assert!(result == 5_i64);
+}
+
 fn eval(expr: &Node) -> i64 {
     match expr {
         Node::Add { left, right } => eval(left) + eval(right),
@@ -158,13 +173,10 @@ fn ast(input: Vec<Symbol>) -> Result<Node, ParseError> {
     let mut i = 0;
 
     while i < length {
-        // println!("Count: {}", i);
         let s = &input[i];
-        // println!("Symbol: {:?}", s);
         match s {
             Symbol::Number { value } => {
                 stack.push(Node::Number { value: *value });
-                // println!("pushed {value}")
             }
             Symbol::Add => {
                 let left = stack.pop();
@@ -199,8 +211,6 @@ fn ast(input: Vec<Symbol>) -> Result<Node, ParseError> {
         }
         i += 1;
     }
-    // println!("Stack length: {}", stack.len());
-    // println!("Stack: {:?}", stack);
     if stack.len() != 1 {
         return Err(ParseError::WrongTokenError { pos: 1 });
     }