chore(weave): add test for instance code saving (#2734)

tests/trace/test_op_versioning.py

@@ -1,3 +1,4 @@
+import re
 import typing
 
 import numpy as np
@@ -508,3 +509,46 @@ def some_d(v):
     print(saved_code)
 
     assert saved_code == EXPECTED_NO_REPEATS_CODE
+
+
+EXPECTED_INSTANCE_CODE = """import weave
+
+instance = "<test_op_versioning.test_op_instance.<locals>.MyClass object at 0x000000000>"
+
+@weave.op()
+def t(text: str):
+    print(instance._version)
+    return text
+"""
+
+
+def test_op_instance(client):
+    class MyClass:
+        _version: str
+        api_key: str
+
+        def __init__(self, secret: str) -> None:
+            self._version = "1.0.0"
+            self.api_key = secret
+
+    # We want to make sure this secret value is not saved in the code
+    instance = MyClass("sk-1234567890qwertyuiop")
+
+    @weave.op()
+    def t(text: str):
+        print(instance._version)
+        return text
+
+    t("hello")
+
+    ref = weave.obj_ref(t)
+    assert ref is not None
+
+    saved_code = get_saved_code(client, ref)
+    print("SAVED CODE")
+    print(saved_code)
+
+    # Instance address expected to change each run
+    clean_saved_code = re.sub(r"0x[0-9a-fA-F]+", "0x000000000", saved_code)
+
+    assert clean_saved_code == EXPECTED_INSTANCE_CODE