Fix tests

tests/advancedstack.rs

@@ -1,5 +1,7 @@
 extern crate rustijvm;
 
+use std::convert::TryInto;
+
 fn steps(machine: &mut rustijvm::Machine, num: usize) {
     for _ in 0..num {
         machine.step().unwrap();
@@ -44,7 +46,9 @@ fn advancedstack_contents() {
     let size = stack.len();
     assert!(size >= 100);
 
-    let markers = (0..size).filter(|i| { stack.get(*i) == 0x2 }).count();
+    let markers = (0..size).filter(|i| {
+        stack.get(*i).try_into().unwrap_or(0) == 0x2
+    }).count();
     assert!(markers >= 99);
 }
 
@@ -55,7 +59,9 @@ fn advancedstack_method() {
     steps(&mut machine, 8);
     {
         let stack = machine.cur_stack();
-        let markers = (0..stack.len()).filter(|i| { stack.get(*i) == 0x2 }).count();
+        let markers = (0..stack.len()).filter(|i| {
+            stack.get(*i).try_into().unwrap_or(0) == 0x2
+        }).count();
         assert_eq!(markers, 4);
     }
 
@@ -63,7 +69,9 @@ fn advancedstack_method() {
     steps(&mut machine, 2 * 5000);
     {
         let stack = machine.cur_stack();
-        let markers = (0..stack.len()).filter(|i| { stack.get(*i) == 0x2 }).count();
+        let markers = (0..stack.len()).filter(|i| {
+            stack.get(*i).try_into().unwrap_or(0) == 0x2
+        }).count();
         assert!(markers > 4000);
     }
 }