TEST: stop GCG unit tests from hitting HuggingFace

[romanlutz]

Description

Five tests under tests/unit/auxiliary_attacks/gcg/ silently downloaded the gpt2 tokenizer at test time via AutoTokenizer.from_pretrained("gpt2"). When HuggingFace rate-limits (429), the dev_all matrix on windows-latest + Python 3.10 fails on otherwise-unrelated PRs (most recent example: 5 OSError: We couldn't connect to 'https://huggingface.co' ... failures on PR #1866). Per .github/instructions/test.instructions.md, unit tests must not hit the network.

This PR splits the offenders two ways based on what each test actually needs gpt2 for:

• Mocked in place -- the lone tokenizer-edge-case test test_gcg_core.py::TestUpdateIdsErrorPaths::test_end_tok_returns_len_toks_when_target_is_at_prompt_end was rewritten to use a fully-mocked tokenizer where encoding.char_to_token returns None past the target's end. This mirrors the pattern already used by the two adjacent test_start_tok_* tests in the same class, so it both fits in and exercises the exact return len(toks) if tok is None else tok branch in end_tok.

• Moved to integration -- four wiring tests that exist precisely to exercise the real chat-template pipeline end-to-end (constructing real IndividualPromptAttack / ProgressiveMultiPromptAttack and running them through _update_ids). Mocking the tokenizer richly enough to satisfy that pipeline would defeat the test's purpose. Destination matches the existing tests/integration/auxiliary_attacks/test_gcg_integration.py precedent (same gpt2 + custom chat-template pattern):

  • whole tests/unit/auxiliary_attacks/gcg/test_attack_wiring.py (both tests in it)
  • just the TestCreateAttackWiring class extracted from tests/unit/auxiliary_attacks/gcg/test_generator.py

  Consolidated into a new tests/integration/auxiliary_attacks/test_gcg_attack_wiring_integration.py. No @pytest.mark.run_only_if_all_tests marker -- that marker is for tests needing real API credentials; these only need a HF tokenizer, and the precedent file doesn't use it either.

GitHub Actions PR CI only runs make unit-test, so this fully removes the offenders from the PR-time matrix. The Azure DevOps integration pipeline still exercises them on push to main.

Tests and Documentation

Verified:

• uv run pytest tests/unit/auxiliary_attacks/gcg/ -> 110 passed, no network
• uv run --with pytest-socket pytest tests/unit/auxiliary_attacks/gcg/ --disable-socket --allow-hosts=127.0.0.1,localhost,::1 -> 110 passed (empirical proof: any off-loopback socket call would raise SocketBlockedError)
• uv run pytest tests/integration/auxiliary_attacks/test_gcg_attack_wiring_integration.py -> 4 passed
• rg 'from_pretrained\("gpt2"\)' tests/unit/ -> no matches
• pre-commit (ruff format + ruff check) clean

No documentation changes needed; this is a test-only refactor.

Out of scope but noted

tests/unit/prompt_converter/test_pdf_converter.py::test_filename_extension_existing_pdf makes a real requests.get to raw.githubusercontent.com/.../fake_CV.pdf -- same class of bug but not in today's failing job. Worth a separate follow-up.