diff --git a/src/simulator/machine.rs b/src/simulator/machine.rs
index 26f4eae..e336842 100644
--- a/src/simulator/machine.rs
+++ b/src/simulator/machine.rs
@@ -139,9 +139,10 @@ impl Machine {
 	/// ### Parameters
 	/// 
 	/// - **machine** which contains a table of instructions
-	pub fn run(&mut self){
-		loop {
-			self.one_instruction();
+	pub fn run(machine : Machine){
+		let mut m = machine;
+		loop{
+			Machine::one_instruction(&mut m);
 		}
 	}
 
@@ -150,8 +151,8 @@ impl Machine {
 	/// ### Parameters
 	/// 
 	/// - **machine** which contains a table of instructions and a pc to the actual instruction
-	pub fn one_instruction(&mut self) {
-		let mut machine = self;
+	pub fn one_instruction(machine :&mut Machine) {
+	
 		let unsigned_reg1 : u64;
 		let unsigned_reg2 : u64;
 		let long_result : i128;
@@ -465,21 +466,11 @@ impl Machine {
 
 #[cfg(test)]
  mod test {
-    use crate::simulator::{machine::Machine, decode};
-
-
-	fn init() -> Machine {
-		let mut m = Machine::_init_machine();
-		m.main_memory[0] = 255;
-		m.main_memory[1] = 43;
-		m.main_memory[2] = 7;
-		m.main_memory[3] = 157;
-		m
-	}
+    use crate::simulator::machine::Machine;
 
 	#[test]
 	fn test_read_memory() {
-		let mut m = init();
+		let mut m = Machine::_init_machine();
     	m.main_memory[4] = 43;
     	m.main_memory[5] = 150;
 		assert_eq!((43 << 8) + 150, Machine::read_memory(&mut m, 2, 4));
@@ -487,50 +478,9 @@ impl Machine {
 
 	#[test]
 	fn test_write_memory() {
-		let mut m = init();
+		let mut m = Machine::_init_machine();
 		Machine::write_memory(&mut m, 2, 6, (43 << 8) + 150);
 		assert_eq!(43, m.main_memory[6]);
 		assert_eq!(150, m.main_memory[7]);
 	}
-
-	#[test]
-	fn test_op_add() {
-		let mut m = init();
-		m.int_reg[6] = 5; // t1
-		m.instructions[0] = 0b0000000_00110_00000_000_00101_0110011;
-		// add t0, zero, t1
-		m.one_instruction();
-		assert_eq!(m.int_reg[5], 5);
-	}
-
-	#[test]
-	fn test_op_sub() {
-		let mut m = init();
-		m.int_reg[6] = 5; // t1
-		m.instructions[0] = 0b0100000_00110_00000_000_00101_0110011;
-		// sub t0, zero, t1
-		m.one_instruction();
-		assert_eq!(m.int_reg[5], -5);
-	}
-
-	#[test]
-	fn test_op_addi() {
-		let mut m = init();
-		m.int_reg[6] = 5; // t1
-		m.instructions[0] = 0b11111111111_00110_000_00101_0010011;
-		// add t0, t1, 2047
-		m.one_instruction();
-		assert_eq!(m.int_reg[5], 2052);
-	}
-
-	/// Equivalent of subi
-	#[test]
-	fn test_op_addi_neg() {
-		let mut m = init();
-		m.int_reg[6] = -5; // t1
-		m.instructions[0] = 0b11111111111_00110_000_00101_0010011;
-		// addi t0, t1, 2047
-		m.one_instruction();
-		assert_eq!(m.int_reg[5], 2042);
-	}
 }