Make all tests not output anything

tests/advanced5.rs

@@ -4,8 +4,9 @@ use std::sync::{Arc, Mutex};
 use std::io::{Cursor, Seek, SeekFrom, Read};
 
 fn run_calc(input: &'static str, expected: &str) {
-    let rc = Arc::new(Mutex::new(Cursor::new(Vec::new())));
+    let rc = rustijvm::stubs::output_stub();
     let mut machine = rustijvm::Machine::new_from_file("files/advanced/SimpleCalc.ijvm").unwrap();
+
     machine.set_input(Box::new(input.as_bytes()));
     machine.set_output(rc.clone());
     machine.run().unwrap();
@@ -38,3 +39,8 @@ fn advanced5_level3() {
     run_calc("1 1 + 1 1 + 1 1 + 1 1 + 1 1 + +-++?.", "2\n");
     run_calc("9 8 -9 7-9 6-9 5-9 4-9 3-9 2-9 1-9 0- -+-+-+-+?.", "1\n");
 }
+
+#[test]
+fn advanced5_level4() {
+    run_calc("2 2 2 2 2 2 2 2 2 2 2 2 2 ************ +?.", "8192\n");
+}