diff --git a/src/machine.rs b/src/machine.rs
index 6c3b663..6361961 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -1,5 +1,6 @@
-use block::Block;
+use std::io::{Read, Write};
 
+use block::Block;
 use ops::Operation;
 use ijvmreader::IJVMReader;
 use binread::{BinRead, BinReadable};
@@ -8,26 +9,36 @@ use stack::Stack;
 use pool::Pool;
 use netstack::NetStack;
 use Result;
+use std::sync::Mutex;
+use std::rc::Rc;
 
 const MAGIC_HEADER:u32 = 0x1DEA_DFAD;
 const ANTI_BS_SIZE:usize = 0xFFFF;
 
 pub struct Machine {
     pub wide: bool,
+    pub halted: bool,
     pub pool: Pool,
     pub block: Block,
     pub frame: Vec<Frame>,
-    pub net: NetStack
+    pub net: NetStack,
+
+    pub stream_in: Box<Read>,
+    pub stream_out: Rc<Mutex<Write>>,
+
 }
 
 impl Machine {
     pub fn new(pool: Pool, block: Block) -> Machine{
         Machine {
             wide: false,
+            halted: false,
             pool,
             block,
             frame: vec![Frame::new(ANTI_BS_SIZE)],
             net: NetStack::new(),
+            stream_in: Box::new(::std::io::stdin()),
+            stream_out: Rc::new(Mutex::new(::std::io::stdout())),
         }
     }
 
@@ -72,14 +83,25 @@ impl Machine {
         }
     }
 
+    pub fn run(&mut self) -> Result<()> {
+        while self.has_step() {
+            self.step()?;
+        }
+        Ok(())
+    }
+
     pub fn has_step(&self) -> bool {
-        self.block.has_i8()
+        !self.halted && self.block.has_i8()
     }
 
     pub fn get_program_counter(&self) -> usize {
         self.block.cur()
     }
 
+    pub fn get_tos(&mut self) -> Result<i32> {
+        self.cur_stack().top()
+    }
+
     pub fn cur_frame(&mut self) -> &mut Frame {
         self.frame.last_mut().unwrap()
     }
@@ -88,6 +110,10 @@ impl Machine {
         &mut self.cur_frame().stack
     }
 
+    pub fn cur_instruction(&mut self) -> u8 {
+        self.block[self.get_program_counter()]
+    }
+
 //    pub fn get_stack_pointer(&self) -> usize {
 //        return self.frame.last().unwrap().stack.len();
 //    }
@@ -99,4 +125,12 @@ impl Machine {
         }
         Ok(self.block.read_u8()? as usize)
     }
+
+    pub fn set_input(&mut self, instream: Box<Read>) {
+        self.stream_in = instream;
+    }
+
+    pub fn set_output(&mut self, outstream: Rc<Mutex<Write>>) {
+        self.stream_out = outstream;
+    }
 }
\ No newline at end of file
diff --git a/src/ops.rs b/src/ops.rs
index 0ed2c30..9bdff0a 100644
--- a/src/ops.rs
+++ b/src/ops.rs
@@ -2,8 +2,7 @@ use binread::BinRead;
 use machine::Machine;
 use frame::Frame;
 use Result;
-use std::io::Write;
-use std::io::Read;
+use std::io::{Read};
 
 pub type OpFunc = fn(&mut Machine) -> Result<()>;
 
@@ -79,8 +78,10 @@ fn dup(machine: &mut Machine) -> Result<()> {
 
 fn out(machine: &mut Machine) -> Result<()> {
     let val = machine.cur_stack().pop()?;
-    print!("{}", val as u8 as char);
-    ::std::io::stdout().flush().unwrap();
+    let buffer = [val as u8];
+    let mut out = machine.stream_out.lock().unwrap();
+    out.write_all(&buffer).unwrap();
+    out.flush().unwrap();
     Ok(())
 }
 
@@ -104,14 +105,10 @@ fn isub(machine: &mut Machine) -> Result<()> {
 }
 
 fn _in(machine: &mut Machine) -> Result<()> {
-   let char: Option<u8> =
-       ::std::io::stdin()
-       .bytes()
-       .next()
-       .and_then(|r| r.ok());
-    let val = match char {
-        None => 0i32,
-        Some(i) => i32::from(i)
+    let mut buffer = [0; 1];
+    let val = match machine.stream_in.read_exact(&mut buffer) {
+        Err(_) => 0i32,
+        Ok(_) => i32::from(buffer[0]),
     };
     machine.cur_stack().push(val);
     Ok(())
@@ -122,8 +119,9 @@ fn goto(machine: &mut Machine) -> Result<()> {
     machine.block.jump(offset)
 }
 
-fn halt(_: &mut Machine) -> Result<()> {
-    Err("Halt")
+fn halt(machine: &mut Machine) -> Result<()> {
+    machine.halted = true;
+    Ok(())
 }
 
 fn ifeq(machine: &mut Machine) -> Result<()> {
@@ -181,7 +179,7 @@ fn swap(machine: &mut Machine) -> Result<()> {
 
 fn wide(machine: &mut Machine) -> Result<()> {
     machine.wide = true;
-    Ok(())
+    machine.step()
 }
 
 fn iload(machine: &mut Machine) -> Result<()> {
@@ -208,7 +206,7 @@ fn invokevirtual(machine: &mut Machine) -> Result<()> {
     let method_index = machine.block.read_u16()?;
     let invoke_addr = machine.pool.get(method_index as usize)?;
     let return_addr = machine.get_program_counter();
-//    println!("METHOD {}", method_index);
+
     machine.block.seek(invoke_addr as usize)?;
     let arg_count = machine.block.read_u16()?;
     let var_count = machine.block.read_u16()?;
@@ -224,7 +222,6 @@ fn invokevirtual(machine: &mut Machine) -> Result<()> {
         cur_stack.pop()?; // Nuke the OBJREF
     }
 
-//    println!("retaddr set {}" ,return_addr);
     newframe.set(0, return_addr as i32)?;
 
     machine.frame.push(newframe);
@@ -237,10 +234,8 @@ fn ireturn(machine: &mut Machine) -> Result<()> {
         Some(a) => a,
         None => return Err("Got no frame... somehow...")
     };
-//    println!("stack: {:?}", prev_frame.stack);
     let result = prev_frame.stack.pop()?;
     let return_addr = prev_frame.get(0)?;
-//    println!("result: {}\nretaddr: {}", result, return_addr);
     machine.cur_stack().push(result);
     machine.block.seek(return_addr as usize)
 }
diff --git a/src/stack.rs b/src/stack.rs
index 4466118..2a1f118 100644
--- a/src/stack.rs
+++ b/src/stack.rs
@@ -12,9 +12,13 @@ impl Stack {
         }
     }
 
-//    pub fn len(&self) -> usize {
-//        return self.data.len();
-//    }
+    pub fn len(&self) -> usize {
+        self.data.len()
+    }
+
+    pub fn get(&self, i: usize) -> i32 {
+        self.data[i]
+    }
 
     pub fn top(&self) -> Result<i32> {
         Ok(match  self.data.last() {
diff --git a/tests/advanced1.rs b/tests/advanced1.rs
new file mode 100644
index 0000000..8b498a6
--- /dev/null
+++ b/tests/advanced1.rs
@@ -0,0 +1,242 @@
+extern crate rustijvm;
+
+use std::rc::Rc;
+use std::sync::Mutex;
+use std::io::{Cursor, Seek, SeekFrom, Read};
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn advanced1() {
+    let output: Rc<Mutex<Cursor<Vec<u8>>>> = Rc::new(Mutex::new(Cursor::new(Vec::new())));
+    let input = Box::new("A".as_bytes());
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/all_regular.ijvm").unwrap();
+    machine.set_input(input);
+    machine.set_output(output.clone());
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(16));
+
+    assert_eq!(0x59, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(16));
+
+    assert_eq!(0xa7, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x60, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(32));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(33));
+
+    assert_eq!(0x7e, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(32));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(2));
+
+    assert_eq!(0xB0, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(3));
+
+    assert_eq!(0x64, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(29));
+
+    assert_eq!(0x00, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(29));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(68));
+
+    assert_eq!(0x60, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(97));
+
+    assert_eq!(0xFD, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    {
+        let mut outstream = output.lock().unwrap();
+        outstream.seek(SeekFrom::Start(0)).unwrap();
+        let mut buf = [0; 1];
+        outstream.read_exact(&mut buf).unwrap();
+        assert_eq!(buf[0], 'a' as u8);
+    }
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0));
+
+    assert_eq!(0x99, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(-22));
+
+    assert_eq!(0x9B, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x13, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(65));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x41));
+
+    assert_eq!(0x9F, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x36, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x84, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(2));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0xFC, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok('A' as i32));
+
+    assert_eq!(0xFC, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0));
+
+    assert_eq!(0x99, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(2));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(3));
+
+    assert_eq!(0xB6, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(2));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(3));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(5));
+
+    assert_eq!(0xB6, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(10));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0));
+
+    assert_eq!(0x10, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(1));
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(5));
+
+    assert_eq!(0xB6, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0x15, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(5));
+
+    assert_eq!(0xAC, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(5));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(10));
+
+    assert_eq!(0xAC, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(10));
+
+    assert_eq!(0x00, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0xAC, machine.cur_instruction());
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(10));
+
+    assert_eq!(0x57, machine.cur_instruction());
+    steps(&mut machine, 1);
+
+    assert_eq!(0xFF, machine.cur_instruction());
+    steps(&mut machine, 1);
+}
+
diff --git a/tests/advanced2.rs b/tests/advanced2.rs
new file mode 100644
index 0000000..993e441
--- /dev/null
+++ b/tests/advanced2.rs
@@ -0,0 +1,61 @@
+extern crate rustijvm;
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn advanced2_nested_invoke_simple() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/test-nestedinvoke-simple.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    let pc_main = machine.get_program_counter() + 3;
+    steps(&mut machine, 1);
+
+    assert_ne!(machine.get_program_counter(), pc_main);
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_tos(), Ok(0x9));
+
+    let pc_magic = machine.get_program_counter() + 3;
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_program_counter(), pc_magic);
+
+    let pc_addone = machine.get_program_counter() + 3;
+    steps(&mut machine, 2);
+    assert_ne!(machine.get_program_counter(), pc_addone);
+    assert_eq!(machine.get_program_counter(), pc_magic);
+
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_program_counter(), pc_magic);
+    assert_eq!(machine.get_program_counter(), pc_main);
+}
+
+#[test]
+fn advanced2_nested_invoke() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/test-nestedinvoke.ijvm").unwrap();
+
+    steps(&mut machine, 8);
+    assert_eq!(machine.get_tos(), Ok(0x6));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x9));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x9));
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_tos(), Ok(0x9));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x9));
+    steps(&mut machine, 1);
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x9));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0xA));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0xA));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_tos(), Ok(0xA));
+}
diff --git a/tests/advanced3.rs b/tests/advanced3.rs
new file mode 100644
index 0000000..5370d59
--- /dev/null
+++ b/tests/advanced3.rs
@@ -0,0 +1,37 @@
+extern crate rustijvm;
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn advanced3_wide1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/test-wide1.ijvm").unwrap();
+
+    steps(&mut machine, 6);
+    assert_eq!(machine.cur_frame().get(1), Ok(0x1));
+    steps(&mut machine, 2);
+    assert_eq!(machine.cur_frame().get(257), Ok(0x2));
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
+
+#[test]
+fn advanced3_wide2() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/test-wide2.ijvm").unwrap();
+
+    steps(&mut machine, 6);
+    assert_eq!(machine.cur_frame().get(1), Ok(0x1));
+    steps(&mut machine, 2);
+    assert_eq!(machine.cur_frame().get(32768), Ok(0x2));
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
diff --git a/tests/advanced4.rs b/tests/advanced4.rs
new file mode 100644
index 0000000..4ef1d75
--- /dev/null
+++ b/tests/advanced4.rs
@@ -0,0 +1,21 @@
+extern crate rustijvm;
+
+use std::rc::Rc;
+use std::sync::Mutex;
+use std::io::{Cursor, Seek, SeekFrom, Read};
+
+#[test]
+fn advanced4_tanenbaum() {
+    let rc = Rc::new(Mutex::new(Cursor::new(Vec::new())));
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/Tanenbaum.ijvm").unwrap();
+    machine.set_output(rc.clone());
+    machine.run().unwrap();
+
+    let mut out = rc.lock().unwrap();
+    let mut string = String::new();
+
+    out.seek(SeekFrom::Start(0)).unwrap();
+    out.read_to_string(&mut string).unwrap();
+
+    assert_eq!(string, "OK");
+}
diff --git a/tests/advancedstack.rs b/tests/advancedstack.rs
new file mode 100644
index 0000000..8f79bc1
--- /dev/null
+++ b/tests/advancedstack.rs
@@ -0,0 +1,69 @@
+extern crate rustijvm;
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn advancedstack_100() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/teststack.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    steps(&mut machine, 2 * 100);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
+
+#[test]
+fn advancedstack_3000() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/teststack.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    steps(&mut machine, 2 * 3000);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
+
+#[test]
+fn advancedstack_50000() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/teststack.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    steps(&mut machine, 2 * 50000);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
+
+#[test]
+fn advancedstack_contents() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/teststack.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    steps(&mut machine, 2 * 100);
+
+    let stack = machine.cur_stack();
+    let size = stack.len();
+    assert!(size >= 100);
+
+    let markers = (0..size).filter(|i| { stack.get(*i) == 0x2 }).count();
+    assert!(markers >= 99);
+}
+
+#[test]
+fn advancedstack_method() {
+    let mut machine = rustijvm::Machine::new_from_file("files/advanced/teststack2.ijvm").unwrap();
+
+    steps(&mut machine, 8);
+    {
+        let stack = machine.cur_stack();
+        let markers = (0..stack.len()).filter(|i| { stack.get(*i) == 0x2 }).count();
+        assert_eq!(markers, 4);
+    }
+
+    steps(&mut machine, 1);
+    steps(&mut machine, 2 * 5000);
+    {
+        let stack = machine.cur_stack();
+        let markers = (0..stack.len()).filter(|i| { stack.get(*i) == 0x2 }).count();
+        assert!(markers > 4000);
+    }
+}
diff --git a/tests/task2.rs b/tests/task2.rs
index 649de47..cf75571 100644
--- a/tests/task2.rs
+++ b/tests/task2.rs
@@ -2,7 +2,6 @@ extern crate rustijvm;
 
 fn steps(machine: &mut rustijvm::Machine, num: usize) {
     for _ in 0..num {
-        println!("step");
         machine.step().unwrap();
     }
 }
@@ -11,78 +10,78 @@ fn steps(machine: &mut rustijvm::Machine, num: usize) {
 fn task2_simple_bipush() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestBipush1.ijvm").unwrap();
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(42));
+    assert_eq!(machine.get_tos(), Ok(42));
 }
 
 #[test]
 fn task2_signed_bipush() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestBipush2.ijvm").unwrap();
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(-42));
+    assert_eq!(machine.get_tos(), Ok(-42));
 }
 
 #[test]
 fn task2_simple_iadd() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIadd1.ijvm").unwrap();
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(60));
+    assert_eq!(machine.get_tos(), Ok(60));
 }
 
 #[test]
 fn task2_signed_iadd() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIadd2.ijvm").unwrap();
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(-60));
+    assert_eq!(machine.get_tos(), Ok(-60));
 }
 
 #[test]
 fn task2_simple_isub() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIsub1.ijvm").unwrap();
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(-10));
+    assert_eq!(machine.get_tos(), Ok(-10));
 }
 
 #[test]
 fn task2_signed_isub() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIsub2.ijvm").unwrap();
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(10));
+    assert_eq!(machine.get_tos(), Ok(10));
 }
 
 #[test]
 fn task2_simple_iand() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIAND1.ijvm").unwrap();
     steps(&mut machine, 5);
-    assert_eq!(machine.cur_stack().top(), Ok(1));
+    assert_eq!(machine.get_tos(), Ok(1));
 }
 
 #[test]
 fn task2_simple_ior() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestIOR1.ijvm").unwrap();
     steps(&mut machine, 5);
-    assert_eq!(machine.cur_stack().top(), Ok(127));
+    assert_eq!(machine.get_tos(), Ok(127));
 }
 
 #[test]
 fn task2_swap() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestSwap1.ijvm").unwrap();
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(10));
+    assert_eq!(machine.get_tos(), Ok(10));
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(20));
+    assert_eq!(machine.get_tos(), Ok(20));
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(10));
+    assert_eq!(machine.get_tos(), Ok(10));
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(20));
+    assert_eq!(machine.get_tos(), Ok(20));
 }
 
 #[test]
 fn task2_simple_stack_operations() {
     let mut machine = rustijvm::Machine::new_from_file("files/task2/TestPop1.ijvm").unwrap();
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(10));
+    assert_eq!(machine.get_tos(), Ok(10));
     steps(&mut machine, 3);
-    assert_eq!(machine.cur_stack().top(), Ok(50));
+    assert_eq!(machine.get_tos(), Ok(50));
     steps(&mut machine, 1);
-    assert_eq!(machine.cur_stack().top(), Ok(10));
+    assert_eq!(machine.get_tos(), Ok(10));
 }
diff --git a/tests/task3.rs b/tests/task3.rs
new file mode 100644
index 0000000..206b74d
--- /dev/null
+++ b/tests/task3.rs
@@ -0,0 +1,128 @@
+extern crate rustijvm;
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn task3_goto1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task3/GOTO1.ijvm").unwrap();
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x31));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_tos(), Ok(0x33));
+    steps(&mut machine, 1);
+}
+
+#[test]
+fn task3_goto2() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task3/GOTO2.ijvm").unwrap();
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x31));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_tos(), Ok(0x33));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_tos(), Ok(0x32));
+    steps(&mut machine, 1);
+}
+
+#[test]
+fn task3_ifeq1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task3/IFEQ1.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x5));
+
+    // L2 iteration 1
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x4));
+    steps(&mut machine, 3);
+    let pc = machine.get_program_counter();
+
+    // L2 iteration 2
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_program_counter(), pc);
+
+    // L2 iteration 3
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_program_counter(), pc);
+
+    // L2 iteration 4
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_program_counter(), pc);
+
+    // L2 iteration 5
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x0));
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_program_counter(), pc + 15);
+}
+
+#[test]
+fn task3_iflt1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task3/IFLT1.ijvm").unwrap();
+    let mut pc = 0;
+
+    // L1
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_program_counter(), pc + 5);
+    pc = machine.get_program_counter();
+
+    // L2
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_program_counter(), pc + 5);
+    pc = machine.get_program_counter();
+
+    // L3
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_program_counter(), pc + 5);
+    pc = machine.get_program_counter();
+
+    // L4
+    steps(&mut machine, 4);
+    assert_eq!(machine.get_program_counter(), pc + 19);
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x37));
+}
+
+#[test]
+fn task3_ificmpeq1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task3/IFICMPEQ1.ijvm").unwrap();
+    let mut pc = 0;
+
+    // L1
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_program_counter(), pc + 7);
+    pc = machine.get_program_counter();
+
+    // L2
+    steps(&mut machine, 5);
+    assert_eq!(machine.get_program_counter(), pc + 10);
+    pc = machine.get_program_counter();
+
+    // L3
+    steps(&mut machine, 4);
+    assert_eq!(machine.get_program_counter(), pc + 8);
+    pc = machine.get_program_counter();
+
+    // L4
+    for _ in 0..3 {
+        steps(&mut machine, 3);
+        assert_eq!(machine.get_program_counter(), pc);
+        pc = machine.get_program_counter()
+    }
+
+    // L6
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_program_counter(), pc + 9);
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x13));
+}
diff --git a/tests/task4.rs b/tests/task4.rs
new file mode 100644
index 0000000..41f598b
--- /dev/null
+++ b/tests/task4.rs
@@ -0,0 +1,123 @@
+extern crate rustijvm;
+
+use std::io::{Cursor, Read, Seek, SeekFrom};
+use std::rc::Rc;
+use std::sync::Mutex;
+
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn task4_ldcw1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task4/LoadTest1.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+}
+
+#[test]
+fn task4_simple_load() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task4/LoadTest3.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 3);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+}
+
+#[test]
+fn task4_complex_load() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task4/LoadTest2.ijvm").unwrap();
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x0));
+
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2a));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x0));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x4f));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x4b));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+}
+
+#[test]
+fn task4_iteration_load() {
+    let rc = Rc::new(Mutex::new(Cursor::new(Vec::new())));
+
+    let mut machine = rustijvm::Machine::new_from_file("files/task4/LoadTest4.ijvm").unwrap();
+    machine.set_output(rc.clone());
+    machine.run().unwrap();
+
+    let mut out = rc.lock().unwrap();
+    let mut string = String::new();
+
+    out.seek(SeekFrom::Start(0)).unwrap();
+    out.read_to_string(&mut string).unwrap();
+
+    assert_eq!(string, "kjihgfedcbaabcd");
+}
+
+#[test]
+fn task4_iinc() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task4/IINCTest.ijvm").unwrap();
+
+    steps(&mut machine, 4);
+    assert_eq!(machine.cur_frame().get(0), Ok(0));
+    assert_eq!(machine.cur_frame().get(1), Ok(0));
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(0), Ok(0));
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(0), Ok(1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(0), Ok(4));
+
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(1), Ok(0));
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(1), Ok(-1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.cur_frame().get(1), Ok(-4));
+}
diff --git a/tests/task5.rs b/tests/task5.rs
new file mode 100644
index 0000000..4529afa
--- /dev/null
+++ b/tests/task5.rs
@@ -0,0 +1,66 @@
+extern crate rustijvm;
+fn steps(machine: &mut rustijvm::Machine, num: usize) {
+    for _ in 0..num {
+        machine.step().unwrap();
+    }
+}
+
+#[test]
+fn task5_invokenoargs() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/TestInvokeNoArgs.ijvm").unwrap();
+
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_tos(), Ok(0x42));
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_tos(), Ok(0x43));
+    steps(&mut machine, 2);
+    assert_eq!(machine.get_tos(), Ok(0x43));
+}
+
+#[test]
+fn task5_invoke1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/test-invokevirtual1.ijvm").unwrap();
+
+    steps(&mut machine, 3);
+    let pc = machine.get_program_counter();
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_program_counter(), pc + 1);
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 2);
+}
+
+#[test]
+fn task5_ireturn1() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/test-invokevirtual1.ijvm").unwrap();
+
+    steps(&mut machine, 6);
+    assert_eq!(machine.get_tos(), Ok(0x1));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}
+
+#[test]
+fn task5_invoke2() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/test-invokevirtual2.ijvm").unwrap();
+
+    steps(&mut machine, 5);
+    let pc = machine.get_program_counter();
+    steps(&mut machine, 1);
+    assert_ne!(machine.get_program_counter(), pc + 1);
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x3));
+    steps(&mut machine, 3);
+}
+
+#[test]
+fn task5_ireturn2() {
+    let mut machine = rustijvm::Machine::new_from_file("files/task5/test-invokevirtual2.ijvm").unwrap();
+
+    steps(&mut machine, 10);
+    assert_eq!(machine.get_tos(), Ok(0x5));
+    steps(&mut machine, 1);
+    assert_eq!(machine.get_tos(), Ok(0x2));
+}