Adding OutputHandler trait

Implemented the ConsoleOutputHandler for printing to the console.
Will add a OutputHandler to write into an in memory buffer so I can implement tests to check the output of the vm.

src/vm/mod.rs

@@ -1,3 +1,4 @@
+use crate::vm::utils::output_handler::OutputHandler;
 use std::fmt::Debug;
 use std::rc::Rc;
 
@@ -7,6 +8,7 @@ mod value;
 mod block;
 pub(crate) mod opcodes;
 
+mod utils;
 mod virtual_machine;
 
 #[derive(Debug, Clone, PartialEq)]
@@ -28,6 +30,7 @@ pub struct VirtualMachine {
     ip: usize,
     stack: Vec<Value>,
     block: Option<Rc<Block>>,
+    output_handler: Box<dyn OutputHandler>,
 }
 
 #[derive(Debug)]

src/vm/utils/mod.rs

@@ -0,0 +1 @@
+pub(crate) mod output_handler;

src/vm/utils/output_handler.rs

@@ -0,0 +1,13 @@
+use crate::vm::Value;
+
+pub(crate) trait OutputHandler {
+    fn println(&self, value: Value);
+}
+
+pub(crate) struct ConsoleOutputHandler {}
+
+impl OutputHandler for ConsoleOutputHandler {
+    fn println(&self, value: Value) {
+        println!("{}", value);
+    }
+}

src/vm/virtual_machine.rs

@@ -1,5 +1,6 @@
 use crate::compiler::Compiler;
 use crate::vm::opcodes::OpCode;
+use crate::vm::utils::output_handler::ConsoleOutputHandler;
 use crate::vm::{Block, Result, Value, VirtualMachine};
 use std::rc::Rc;
 
@@ -11,6 +12,7 @@ impl VirtualMachine {
             ip: 0,
             stack: Vec::new(),
             block: None,
+            output_handler: Box::new(ConsoleOutputHandler {}),
         }
     }
 
@@ -137,7 +139,7 @@ impl VirtualMachine {
                 }
                 OpCode::Print => {
                     let value = self.pop();
-                    println!("{}", value);
+                    self.output_handler.println(value);
                 }
                 OpCode::Pop => {
                     self.pop();
@@ -214,11 +216,7 @@ mod tests {
         block.write_op_code(super::OpCode::Divide, 0);
         block.write_op_code(super::OpCode::Return, 0);
 
-        let mut vm = super::VirtualMachine {
-            ip: 0,
-            stack: Vec::new(),
-            block: None,
-        };
+        let mut vm = super::VirtualMachine::new();
 
         let result = vm.run(&block);
         assert_eq!(super::Result::Ok, result);
@@ -248,6 +246,7 @@ mod tests {
 
         assert_eq!(super::Result::Ok, result);
     }
+
     #[test]
     fn can_run_multi_line_statements() {
         let program = r#"