[BugFix] Allow model_loader_extra_config with remote_instance + modelexpress backend (#34639)

Signed-off-by: joeltg <joel@reflection.ai> Co-authored-by: mmangkad <176301910+mmangkad@users.noreply.github.com>
2026-08-29 00:43:10 -07:00
parent 78eef34356
commit 0a585d5bb1
2 changed files with 124 additions and 22 deletions
@@ -0,0 +1,77 @@
+"""Unit tests for RemoteInstanceModelLoader construction - no server, no weights."""
+
+import unittest
+
+import sglang.srt.model_loader.loader as loader_mod
+from sglang.srt.configs.load_config import LoadConfig, LoadFormat
+from sglang.srt.model_loader.remote_instance_weight_loader_utils import (
+    RemoteInstanceWeightLoaderBackend,
+)
+from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cpu_ci(est_time=5, suite="base-a-test-cpu")
+
+EXTRA_CONFIG = {"enable_multithread_load": True, "num_threads": 64}
+
+# ServerArgs forwards the backend as a plain str, so every case covers both that
+# and the enum member; the loader's comparison holds only via the str mixin.
+MODELEXPRESS_BACKENDS = (
+    RemoteInstanceWeightLoaderBackend.MODELEXPRESS,
+    "modelexpress",
+)
+OTHER_BACKENDS = (
+    RemoteInstanceWeightLoaderBackend.NCCL,
+    "nccl",
+    RemoteInstanceWeightLoaderBackend.TRANSFER_ENGINE,
+    "transfer_engine",
+)
+ALL_BACKENDS = MODELEXPRESS_BACKENDS + OTHER_BACKENDS
+
+
+def _load_config(backend, extra_config=None):
+    return LoadConfig(
+        load_format=LoadFormat.REMOTE_INSTANCE,
+        model_loader_extra_config=extra_config or {},
+        remote_instance_weight_loader_backend=backend,
+    )
+
+
+class TestRemoteInstanceModelLoaderExtraConfig(CustomTestCase):
+    def test_modelexpress_backend_accepts_extra_config(self):
+        for backend in MODELEXPRESS_BACKENDS:
+            with self.subTest(backend=backend):
+                loader = loader_mod.RemoteInstanceModelLoader(
+                    _load_config(backend, EXTRA_CONFIG)
+                )
+                # ModelExpress hands the extra config to the DefaultModelLoader
+                # it falls back to, so it must survive construction unmodified.
+                self.assertEqual(
+                    loader.load_config.model_loader_extra_config, EXTRA_CONFIG
+                )
+
+    def test_modelexpress_backend_rejects_unknown_extra_config_key(self):
+        for backend in MODELEXPRESS_BACKENDS:
+            with self.subTest(backend=backend):
+                with self.assertRaises(ValueError):
+                    loader_mod.RemoteInstanceModelLoader(
+                        _load_config(backend, {"num_thread": 64})
+                    )
+
+    def test_other_backends_reject_extra_config(self):
+        for backend in OTHER_BACKENDS:
+            with self.subTest(backend=backend):
+                with self.assertRaises(ValueError):
+                    loader_mod.RemoteInstanceModelLoader(
+                        _load_config(backend, EXTRA_CONFIG)
+                    )
+
+    def test_all_backends_construct_without_extra_config(self):
+        for backend in ALL_BACKENDS:
+            with self.subTest(backend=backend):
+                loader = loader_mod.RemoteInstanceModelLoader(_load_config(backend))
+                self.assertFalse(loader.load_config.model_loader_extra_config)
+
+
+if __name__ == "__main__":
+    unittest.main()