[v1] support quantization (#10161)

tests_v1/plugins/model_plugins/test_quantization_plugin.py

@@ -0,0 +1,51 @@
+# Copyright 2025 the LlamaFactory team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+
+from llamafactory.v1.config.model_args import ModelArguments
+from llamafactory.v1.core.model_engine import ModelEngine
+
+
+bitsandbytes = pytest.importorskip("bitsandbytes")
+
+
+def check_quantization_status(model):
+    quantized_info = {"bnb": []}
+
+    for name, module in model.named_modules():
+        # check BitsAndBytes quantization
+        if isinstance(module, bitsandbytes.nn.modules.Linear8bitLt) or isinstance(
+            module, bitsandbytes.nn.modules.Linear4bit
+        ):
+            quantized_info["bnb"].append(name)
+
+    return quantized_info
+
+
+@pytest.mark.runs_on(["cuda"])
+@pytest.mark.parametrize("name, quantization_bit", [("bnb", 4), ("auto", 4)])
+def test_quantization_plugin(name, quantization_bit):
+    model_args = ModelArguments(
+        model="llamafactory/tiny-random-qwen3",
+        quant_config={
+            "name": name,
+            "quantization_bit": quantization_bit,
+        },
+    )
+
+    model_engine = ModelEngine(model_args=model_args)
+    quantized_info = check_quantization_status(model_engine.model)
+    print(f"Quantized weights for method {name} with {quantization_bit} bit: {quantized_info}")
+    assert any(v for v in quantized_info.values()), "model is not quantized properly."