fix: stop two test modules from mutating global state at import time (#971)

* fix: scope the MAX_INPUT_LENGTH override to this test module

The module set qwen3_embed.common.utils.MAX_INPUT_LENGTH = 100 at import
time. pytest imports every test module during collection, so the override
survived into every other module in the session -- including the ones
deselected by -m, which are imported all the same. Five integration tests
failed with 'exceeds maximum allowed length of 100 characters' on inputs
that are nowhere near any real limit.

The comment justifying it was wrong: check_input_length reads the global
at call time, so it does not need to be set before the modules under test
are imported. tests/test_utils.py already patches it per-test with
monkeypatch.setattr. An autouse fixture does the same here and lets
monkeypatch restore it afterwards.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix: stop injecting a fake llama_cpp into sys.modules for the whole session

The module assigned sys.modules['llama_cpp'] = MagicMock() at import
time. Because pytest imports every test module during collection, the
fake outlived this file and was still in place when
tests/test_integration_gguf.py ran its pytest.importorskip('llama_cpp').
The guard found the fake, declined to skip, and 18 integration tests ran
against a mock and failed -- turning 'the optional backend is not
installed' into 'the backend is broken', which is the opposite reading.

qwen3_embed.text.gguf_embedding imports llama_cpp lazily inside
functions, so importing it needs no mock at all. The tests that do need
one already scope it with patch.dict(sys.modules, ...), the pattern
tests/test_gguf_cross_encoder.py uses.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: n24q02m

tests/test_gguf_embedding.py

@@ -11,17 +11,23 @@
 import numpy as np
 import pytest
 
-# Mock llama_cpp before importing the module under test
-_mock_llama_module = MagicMock()
-sys.modules["llama_cpp"] = _mock_llama_module
-
-from qwen3_embed.text.gguf_embedding import (  # noqa: E402
+from qwen3_embed.text.gguf_embedding import (
     DEFAULT_TASK,
     QUERY_INSTRUCTION_TEMPLATE,
     Qwen3TextEmbeddingGGUF,
     _check_llama_cpp,
 )
 
+# Note: qwen3_embed.text.gguf_embedding imports llama_cpp lazily inside
+# functions (see _check_llama_cpp / Qwen3TextEmbeddingGGUF.__init__), not at
+# module import time, so no sys.modules mock is needed just to import it.
+# Each test below that needs llama_cpp to appear "installed" scopes its own
+# mock via patch.dict(sys.modules, {"llama_cpp": ...}) so nothing leaks into
+# other test modules collected in the same pytest session (in particular,
+# tests/test_integration_gguf.py relies on llama_cpp being genuinely absent
+# so its pytest.importorskip("llama_cpp") can skip when the optional
+# dependency is not installed).
+
 # ---------------------------------------------------------------------------
 # Tests for _check_llama_cpp
 # ---------------------------------------------------------------------------

tests/test_security_limits.py

@@ -1,11 +1,22 @@
 import pytest
 
-# Needs to be set BEFORE modules are imported to affect MAX_INPUT_LENGTH
 import qwen3_embed.common.utils
 import qwen3_embed.rerank.cross_encoder.text_cross_encoder
 import qwen3_embed.text.text_embedding
 
-qwen3_embed.common.utils.MAX_INPUT_LENGTH = 100
+
+@pytest.fixture(autouse=True)
+def _low_max_input_length(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Lower MAX_INPUT_LENGTH for every test in this module.
+
+    check_input_length reads the module global at call time, so patching it
+    per-test (and letting monkeypatch restore it afterwards) is sufficient --
+    it does not need to be set before the modules under test are imported.
+    A low limit lets the tests below exercise the length guard without
+    allocating a huge string, and the patch does not leak into other test
+    modules collected in the same pytest session.
+    """
+    monkeypatch.setattr(qwen3_embed.common.utils, "MAX_INPUT_LENGTH", 100)
 
 
 def test_check_input_length():