fix: Updated visit_mut_fn_decl to return true to allow walking a function to identify nested functions

src/instrumentation.rs

@@ -226,7 +226,7 @@ impl Instrumentation {
                 self.insert_tracing(body);
             }
         }
-        false
+        true
     }
 
     pub fn visit_mut_var_decl(&mut self, node: &mut VarDecl) -> bool {

tests/instrumentor_test.rs

@@ -17,6 +17,7 @@ mod index_cjs;
 mod injection_failure;
 mod multiple_class_method_cjs;
 mod multiple_load_cjs;
+mod nested_functions;
 mod object_method_cjs;
 mod polyfill_cjs;
 mod polyfill_mjs;

tests/nested_functions/mod.js

@@ -0,0 +1,18 @@
+/**
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2025 Datadog, Inc.
+ **/
+
+function fastify() {
+  const fastify = {
+    addHook
+  }
+
+  function addHook() {
+    return 'Hook added';
+  }
+
+  return fastify
+}
+
+module.exports = fastify;

tests/nested_functions/mod.rs

@@ -0,0 +1,15 @@
+use crate::common::*;
+use orchestrion_js::*;
+
+#[test]
+fn nested_fn() {
+    transpile_and_test(
+        file!(),
+        false,
+        Config::new_single(InstrumentationConfig::new(
+            "nested_fn",
+            test_module_matcher(),
+            FunctionQuery::function_declaration("addHook", FunctionKind::Sync),
+        )),
+    );
+}

tests/nested_functions/test.js

@@ -0,0 +1,16 @@
+/**
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2025 Datadog, Inc.
+ **/
+const fastify = require('./instrumented.js');
+const { assert, getContext } = require('../common/preamble.js');
+const context = getContext('orchestrion:undici:nested_fn');
+(async () => {
+  const f = fastify()
+  const result = f.addHook()
+  assert.strictEqual(result, 'Hook added');
+  assert.deepStrictEqual(context, {
+    start: true,
+    end: true,
+  });
+})();