[Bugfix] GLM-Image: route t2i requests through the multimodal processor (#3034) (#3189)

Signed-off-by: Piotr Tarasiewicz <ptarasiewicz@nvidia.com>

tests/inputs/test_preprocess.py

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: Apache-2.0
+"""Unit tests for OmniInputPreprocessor._process_text routing."""
+
+import pytest
+from pytest_mock import MockerFixture
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+class TestProcessTextMmProcessorKwargsRouting:
+    """Presence-based routing: an explicit empty ``mm_processor_kwargs`` dict
+    on the prompt still routes through ``_process_multimodal``. Required for
+    AR-based image generation (e.g. GLM-Image t2i) where the HF processor
+    supplies the image-generation scaffold from its own defaults and no extra
+    kwargs are needed from the caller.
+    """
+
+    @pytest.fixture
+    def preprocessor(self, mocker: MockerFixture):
+        from vllm_omni.inputs.preprocess import OmniInputPreprocessor
+
+        instance = object.__new__(OmniInputPreprocessor)
+        instance._process_multimodal = mocker.MagicMock(return_value={})
+        instance._tokenize_prompt = mocker.MagicMock(return_value=[1, 2, 3])
+        return instance
+
+    def test_empty_mm_processor_kwargs_routes_to_multimodal(self, preprocessor):
+        preprocessor._process_text({"prompt": "hello", "mm_processor_kwargs": {}})
+        assert preprocessor._process_multimodal.called
+        assert not preprocessor._tokenize_prompt.called
+
+    def test_missing_mm_processor_kwargs_routes_to_tokenize(self, preprocessor):
+        preprocessor._process_text({"prompt": "hello"})
+        assert preprocessor._tokenize_prompt.called
+        assert not preprocessor._process_multimodal.called