Fix removed lines from merge

src/opcodes/tests/test_opcodes.cairo

@@ -131,10 +131,13 @@ fn test_op_TRUE() {
     let mut compiler = CompilerTraitImpl::new();
     let bytecode = compiler.compile(program);
     let mut engine = EngineTraitImpl::new(bytecode);
-    
+
     let res = engine.step();
     assert!(res, "Execution of step failed");
-
+
+    let dstack = engine.get_dstack();
+    assert_eq!(dstack.len(), 1, "Stack length is not 1");
+
     let expected_stack = array!["\0\0\0\0\0\0\0\x01"];
     assert_eq!(dstack, expected_stack.span(), "Stack is not equal to expected");
 }
@@ -152,7 +155,7 @@ fn test_op_1add() {
 
     let dstack = engine.get_dstack();
     assert_eq!(dstack.len(), 1, "Stack length is not 1");
-    
+
     let expected_stack = array!["\0\0\0\0\0\0\0\x02"];
     assert_eq!(dstack, expected_stack.span(), "Stack is not equal to expected");
 }