[Bugfix] Offline mode fix (#8376)

Signed-off-by: Joe Runde <Joseph.Runde@ibm.com>

tests/entrypoints/offline_mode/test_offline_mode.py

@@ -0,0 +1,77 @@
+"""Tests for HF_HUB_OFFLINE mode"""
+import importlib
+import sys
+import weakref
+
+import pytest
+
+from vllm import LLM
+
+from ...conftest import cleanup
+
+MODEL_NAME = "facebook/opt-125m"
+
+
+@pytest.fixture(scope="module")
+def llm():
+    # pytest caches the fixture so we use weakref.proxy to
+    # enable garbage collection
+    llm = LLM(model=MODEL_NAME,
+              max_num_batched_tokens=4096,
+              tensor_parallel_size=1,
+              gpu_memory_utilization=0.10,
+              enforce_eager=True)
+
+    with llm.deprecate_legacy_api():
+        yield weakref.proxy(llm)
+
+        del llm
+
+    cleanup()
+
+
+@pytest.mark.skip_global_cleanup
+def test_offline_mode(llm: LLM, monkeypatch):
+    # we use the llm fixture to ensure the model files are in-cache
+    del llm
+
+    # Set HF to offline mode and ensure we can still construct an LLM
+    try:
+        monkeypatch.setenv("HF_HUB_OFFLINE", "1")
+        # Need to re-import huggingface_hub and friends to setup offline mode
+        _re_import_modules()
+        # Cached model files should be used in offline mode
+        LLM(model=MODEL_NAME,
+            max_num_batched_tokens=4096,
+            tensor_parallel_size=1,
+            gpu_memory_utilization=0.10,
+            enforce_eager=True)
+    finally:
+        # Reset the environment after the test
+        # NB: Assuming tests are run in online mode
+        monkeypatch.delenv("HF_HUB_OFFLINE")
+        _re_import_modules()
+        pass
+
+
+def _re_import_modules():
+    hf_hub_module_names = [
+        k for k in sys.modules if k.startswith("huggingface_hub")
+    ]
+    transformers_module_names = [
+        k for k in sys.modules if k.startswith("transformers")
+        and not k.startswith("transformers_modules")
+    ]
+
+    reload_exception = None
+    for module_name in hf_hub_module_names + transformers_module_names:
+        try:
+            importlib.reload(sys.modules[module_name])
+        except Exception as e:
+            reload_exception = e
+            # Try to continue clean up so that other tests are less likely to
+            # be affected
+
+    # Error this test if reloading a module failed
+    if reload_exception is not None:
+        raise reload_exception