test(lfx): guard knowledge-deps probe against the chroma sys.modules shim

The module-level ``find_spec("langchain_chroma")`` crashed collection of the
whole lfx suite with ``ValueError: langchain_chroma.__spec__ is None``. The
KB-backends conftest registers a bare ``types.ModuleType("langchain_chroma")``
shim into ``sys.modules`` when the real package is absent; that shim satisfies
the knowledge module's ``from langchain_chroma import Chroma`` (so it imports),
but its ``__spec__`` is None, which makes ``find_spec`` raise rather than return
a spec. Running the file alone passed (no conftest, no shim); the full
``make lfx_tests`` failed.

Probe via a helper that checks ``sys.modules`` first and guards ``find_spec``
with ``except (ImportError, ValueError)`` — the same pattern the conftest's own
``_is_missing`` uses — so a shimmed, a real, and an absent langchain_chroma all
resolve correctly. Not flakiness and nothing was removed: purely the probe
tripping over another suite's fixture.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dkaushik94

src/lfx/tests/unit/custom/component/test_dynamic_imports.py

@@ -10,18 +10,41 @@
 """
 
 import importlib.util
+import sys
 from unittest.mock import patch
 
 import pytest
 from lfx.components._importing import import_mod
 
-# ``files_and_knowledge.knowledge`` (KnowledgeComponent) imports ``langchain_chroma``
-# at module-import time; every ``langflow`` import in it is lazy. So whether the
-# module — and the component class — imports cleanly depends solely on that one
-# optional dependency being installed. The engine-only lfx test env normally lacks
-# it, but some CI environments carry it transitively, so these tests branch on its
-# presence rather than hard-assuming it is absent (mirrors ``test_type_checking_imports``).
-_KNOWLEDGE_DEPS_AVAILABLE = importlib.util.find_spec("langchain_chroma") is not None
+
+def _knowledge_deps_available() -> bool:
+    """Whether the knowledge module's ``langchain_chroma`` import can resolve.
+
+    ``files_and_knowledge.knowledge`` (KnowledgeComponent) imports
+    ``langchain_chroma`` at module-import time; every ``langflow`` import in it
+    is lazy. So whether that module — and the component class — imports cleanly
+    depends solely on this one optional dependency being importable. The
+    engine-only lfx test env normally lacks it, but some CI environments carry
+    it transitively, so these tests branch on its presence rather than
+    hard-assuming it is absent (mirrors ``test_type_checking_imports``).
+
+    Must tolerate the KB-backends conftest, which registers a bare
+    ``types.ModuleType("langchain_chroma")`` shim into ``sys.modules`` when the
+    real package is missing. That shim still satisfies ``from langchain_chroma
+    import Chroma`` — so the knowledge module imports — but its ``__spec__`` is
+    ``None``, which makes ``find_spec`` raise ``ValueError``. Check
+    ``sys.modules`` first, and guard ``find_spec`` the same way the conftest's
+    own ``_is_missing`` helper does.
+    """
+    if "langchain_chroma" in sys.modules:
+        return True
+    try:
+        return importlib.util.find_spec("langchain_chroma") is not None
+    except (ImportError, ValueError):
+        return False
+
+
+_KNOWLEDGE_DEPS_AVAILABLE = _knowledge_deps_available()
 
 
 class TestImportUtils: