add test for arguments mutation

Author: simon-id

tests/arguments_mutation/mod.js

@@ -0,0 +1,30 @@
+/**
+ * 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 assert = require('assert');
+
+function fetch_simple (url, cb) {
+  assert.strictEqual(this.this, 'this');
+  assert.strictEqual(url, 'https://example.com');
+  assert.strictEqual(cb.length, 2);
+  const result = cb.apply(this, ['arg1', 'arg2']);
+  assert.strictEqual(result, 'result');
+  return 'return';
+}
+
+function fetch_complex ({ url, tuple: [a = 'a', b = 'b'] }, cb, optional = 'default', ...rest) {
+  assert.strictEqual(this.this, 'this');
+  assert.strictEqual(url, 'https://example.com');
+  assert.strictEqual(a, 'a');
+  assert.strictEqual(b, 'b');
+  assert.strictEqual(cb.length, 2);
+  assert.strictEqual(optional, 'default');
+  assert.deepStrictEqual(rest, []);
+  const result = cb.apply(this, ['arg1', 'arg2']);
+  assert.strictEqual(result, 'result');
+  return 'return';
+}
+
+
+module.exports = { fetch_simple, fetch_complex };

tests/arguments_mutation/mod.rs

@@ -0,0 +1,25 @@
+use crate::common::*;
+use orchestrion_js::*;
+
+#[test]
+fn arguments_mutation() {
+    transpile_and_test(
+        file!(),
+        false,
+        Config::new(
+            vec![
+                InstrumentationConfig::new(
+                    "fetch_simple",
+                    test_module_matcher(),
+                    FunctionQuery::function_declaration("fetch_simple", FunctionKind::Sync),
+                ),
+                InstrumentationConfig::new(
+                    "fetch_complex",
+                    test_module_matcher(),
+                    FunctionQuery::function_declaration("fetch_complex", FunctionKind::Sync),
+                ),
+            ],
+            None,
+        ),
+    );
+}

tests/arguments_mutation/test.js

@@ -0,0 +1,39 @@
+/**
+ * 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 { fetch_simple, fetch_complex } = require('./instrumented.js');
+const assert = require('assert');
+const { tracingChannel } = require('diagnostics_channel');
+
+const handler = {
+  start (message) {
+    const originalCb = message.arguments[1];
+    const wrappedCb = function (a, b) {
+      assert.strictEqual(this.this, 'this');
+      assert.strictEqual(a, 'arg1');
+      assert.strictEqual(b, 'arg2');
+      arguments[1] = 'arg2_mutated';
+      return originalCb.apply(this, arguments);
+    }
+
+    message.arguments[1] = wrappedCb;
+  }
+};
+
+tracingChannel('orchestrion:undici:fetch_simple').subscribe(handler);
+tracingChannel('orchestrion:undici:fetch_complex').subscribe(handler);
+
+
+assert.strictEqual(fetch_simple.length, 2);
+assert.strictEqual(fetch_complex.length, 2);
+
+const cb = function (a, b) {
+  assert.strictEqual(this.this, 'this');
+  assert.strictEqual(a, 'arg1');
+  assert.strictEqual(b, 'arg2_mutated');
+  return 'result';
+};
+
+assert.strictEqual(fetch_simple.apply({ this: 'this' }, ['https://example.com', cb]), 'return');
+assert.strictEqual(fetch_complex.apply({ this: 'this' }, [{ url: 'https://example.com' }, cb]), 'return');

tests/instrumentor_test.rs

@@ -4,6 +4,7 @@
  **/
 mod common;
 
+mod arguments_mutation;
 mod class_method_cjs;
 mod constructor_cjs;
 mod constructor_mjs;