RecursionError in __getattr__ Dynamic Import System

[mencnert]

Summary

Bug Report: The mergepythonclient library (version 2.3.1) contains a critical flaw in its dynamic import system that causes infinite recursion when tools like freezegun attempt to introspect module attributes. This results in a RecursionError: maximum recursion depth exceeded and prevents the library
from being used in testing environments that rely on module introspection.

Environment

• Package: mergepythonclient version 2.3.1
• Python: 3.13.2 (also affects other Python versions)
• Platform: All platforms (tested on macOS Darwin 24.6.0)
• Trigger: Module introspection tools (e.g., freezegun, potentially others)

Root Cause

The issue is located in /merge/resources/init.py where the _dynamic_imports dictionary contains self-referential entries:

  _dynamic_imports: typing.Dict[str, str] = {
      "accounting": ".",  # ← Problematic: "." refers to the same module
      "ats": ".",
      "crm": ".",
      "filestorage": ".",
      "hris": ".",
      "ticketing": ".",
  }

When the getattr method is triggered:

1. import_module(".", package) imports the same module (merge.resources)
2. getattr(module, attr_name) attempts to access the attribute on the same module
3. This triggers getattr again → infinite recursion

Reproduction Steps

"""
Reproduces the RecursionError in mergepythonclient 2.3.1
Save as reproduce_bug.py and run: python reproduce_bug.py
"""

import sys
import traceback


def test_recursion_bug():
    try:
        from freezegun import freeze_time

        @freeze_time("2025-01-01T00:00:00")
        def dummy_test():
            return "success"

        result = dummy_test()
        print("✅ Test passed:", result)

    except RecursionError as e:
        print("❌ RecursionError occurred:")
        print(f"Error: {str(e)}")
        tb = traceback.format_exc()
        print(tb)
        return False
    except Exception as e:
        print(f"❌ Other error: {e}")
        return False

    return True


if __name__ == "__main__":
    print("Testing mergepythonclient recursion bug...")
    print(f"Python version: {sys.version}")

    # Check if merge is installed
    try:
        import merge

        print(f"Merge version: {getattr(merge, '__version__', 'unknown')}")
    except ImportError:
        print(
            "❌ mergepythonclient not installed. Install with: pip install mergepythonclient"
        )
        sys.exit(1)

    success = test_recursion_bug()
    if not success:
        print("\n🐛 Bug confirmed: RecursionError in mergepythonclient")
        sys.exit(1)

Stack trace

Traceback (most recent call last):
  File "/Users/user/devel/bug/test.py", line 18, in test_recursion_bug
    result = dummy_test()
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 901, in wrapper
    with self as time_factory:
         ^^^^
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 717, in __enter__
    return self.start()
           ~~~~~~~~~~^^
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 806, in start
    module_attrs = _get_cached_module_attributes(module)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 144, in _get_cached_module_attributes
    _setup_module_cache(module)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 123, in _setup_module_cache
    all_module_attributes = _get_module_attributes(module)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/freezegun/api.py", line 112, in _get_module_attributes
    attribute_value = getattr(module, attribute_name)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/merge/__init__.py", line 33, in __getattr__
    result = getattr(module, attr_name)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/merge/resources/__init__.py", line 26, in __getattr__
    result = getattr(module, attr_name)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/merge/resources/__init__.py", line 26, in __getattr__
    result = getattr(module, attr_name)
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/merge/resources/__init__.py", line 26, in __getattr__
    result = getattr(module, attr_name)
  [Previous line repeated 985 more times]
  File "/Users/user/devel/bug/.venv/lib/python3.13/site-packages/merge/resources/__init__.py", line 25, in __getattr__
    module = import_module(module_name, __package__)
  File "/Users/user/.local/share/mise/installs/python/3.13.2/lib/python3.13/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1384, in _gcd_import
RecursionError: maximum recursion depth exceeded

Impact

• Critical: Prevents use of mergepythonclient in test environments using freezegun
• Widespread: Affects any tool that performs module introspection

Suggested Fix

Replace the self-referential "." entries in /merge/resources/init.py:

Current (Broken) Code:

  _dynamic_imports: typing.Dict[str, str] = {
      "accounting": ".",
      "ats": ".",
      "crm": ".",
      "filestorage": ".",
      "hris": ".",
      "ticketing": ".",
  }

Suggested Fix:

  _dynamic_imports: typing.Dict[str, str] = {
      "accounting": ".accounting",
      "ats": ".ats",
      "crm": ".crm",
      "filestorage": ".filestorage",
      "hris": ".hris",
      "ticketing": ".ticketing",
  }

Alternative Safer Approach:

Add recursion protection to the getattr method:

  _in_getattr = set()

  def __getattr__(attr_name: str) -> typing.Any:
      if attr_name in _in_getattr:
          raise AttributeError(f"Recursive access detected for {attr_name}")

      module_name = _dynamic_imports.get(attr_name)
      if module_name is None:
          raise AttributeError(f"No {attr_name} found in _dynamic_imports for module name -> {__name__}")

      try:
          _in_getattr.add(attr_name)
          module = import_module(module_name, __package__)
          result = getattr(module, attr_name)
          return result
      except ImportError as e:
          raise ImportError(f"Failed to import {attr_name} from {module_name}: {e}") from e
      except AttributeError as e:
          raise AttributeError(f"Failed to get {attr_name} from {module_name}: {e}") from e
      finally:
          _in_getattr.discard(attr_name)

Workarounds for Users

Until fixed, users can work around this issue by configuring freezegun to ignore the merge package:

  import freezegun
  freezegun.configure(extend_ignore_list=['merge'])

Additional Notes

• This bug was introduced in the dynamic import system design
• The same pattern may exist in other auto-generated SDK code
• Testing with module introspection tools should be part of the CI/CD pipeline
• Consider adding unit tests that use freezegun or similar introspection tools

Repository Information

• Repository: https://github.com/merge-api/merge-python-client
• Package: https://pypi.org/project/mergepythonclient/
• Current Version: 2.3.1 (affected)

Thank you for maintaining this library! This fix would greatly improve compatibility with testing frameworks.

[fern-support]

Thank you for the detailed bug report and suggested fixes @mencnert! We'll take a look at this soon.

[connorn314]

Still running into this with v2.6.0, same setup