Add test case for bug

tests/func_builder.rs

@@ -1,8 +1,12 @@
-use orca_wasm::ir::id::FunctionID;
+use orca_wasm::ir::id::{FunctionID, TypeID};
 use orca_wasm::opcode::Instrumenter;
-use orca_wasm::Opcode;
+use orca_wasm::{DataType, Opcode};
 use orca_wasm::{Location, Module};
 use std::process::Command;
+use log::trace;
+use orca_wasm::ir::function::FunctionBuilder;
+use orca_wasm::iterator::iterator_trait::Iterator;
+use orca_wasm::iterator::module_iterator::ModuleIterator;
 
 // #[test]
 // build factorial from scratch
@@ -61,3 +65,33 @@ fn run_start_orca_default() {
     let out = wasmprinter::print_bytes(result.clone()).expect("couldn't translate Wasm to wat");
     println!("{}", out);
 }
+#[test]
+// test start function instrumentation with FunctionModifier
+fn add_import_and_local_fn_then_iterate() {
+    let file_name = "tests/test_inputs/handwritten/modules/_start.wat";
+    let wasm = wat::parse_file(file_name).expect("couldn't convert the input wat to Wasm");
+    let mut module = Module::parse(&wasm, false).expect("Unable to parse");
+    // add an imported function AND THEN a new local function
+    module.add_import_func("new".to_string(), "import".to_string(), TypeID(0));
+    assert_eq!(module.num_import_func(), 1);
+
+    let params = vec![];
+    let results = vec![DataType::I32];
+
+    let mut new_func = FunctionBuilder::new(&params, &results);
+    new_func.i32_const(1);
+    new_func.finish_module(&mut module);
+
+    // now iterate over module
+    let mut mod_it = ModuleIterator::new(&mut module, &vec![]);
+    loop {
+        let _op = mod_it.curr_op();
+        if mod_it.next().is_none() {
+            break;
+        };
+    }
+
+    let result = module.encode();
+    let out = wasmprinter::print_bytes(result.clone()).expect("couldn't translate Wasm to wat");
+    println!("{}", out);
+}