[Bugfix][MiniCPM-o] Align structured chat content with native omni rendering (#7344)

Signed-off-by: Sy03 <1370724210@qq.com>

tests/model_executor/models/minicpmo_4_5/test_chat_template.py

@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+"""MiniCPM structured-content rendering must preserve native part boundaries."""
+
+from pathlib import Path
+
+import pytest
+from jinja2 import TemplateError
+from transformers.utils.chat_template_utils import _compile_jinja_template
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+TEMPLATE = Path(__file__).resolve().parents[4] / "vllm_omni/transformers_utils/chat_templates/minicpmo45_native.jinja"
+
+
+@pytest.mark.parametrize(
+    "parts,expected",
+    [
+        ([{"type": "image"}, {"type": "text", "text": "Question?"}], "(<image>./</image>)Question?"),
+        ([{"type": "text", "text": "Question?"}, {"type": "image"}], "Question?(<image>./</image>)"),
+        ([{"type": "image"}, {"type": "text", "text": "\n\nQuestion?"}], "(<image>./</image>)\n\nQuestion?"),
+        ([{"type": "text", "text": " A "}, {"type": "text", "text": " B "}], " A  B "),
+        ([{"type": "audio"}, {"type": "text", "text": "Transcribe."}], "(<audio>./</audio>)Transcribe."),
+        ([{"type": "video"}, {"type": "image"}], "(<video>./</video>)(<image>./</image>)"),
+        ("\nKeep this whitespace.\n", "\nKeep this whitespace.\n"),
+    ],
+)
+def test_native_content_concatenation(parts, expected):
+    rendered = _compile_jinja_template(TEMPLATE.read_text()).render(
+        messages=[{"role": "user", "content": parts}],
+        add_generation_prompt=True,
+        enable_thinking=False,
+        use_tts_template=True,
+    )
+    assert rendered == (
+        f"<|im_start|>user\n{expected}<|im_end|>\n<|im_start|>assistant\n<think>\n\n</think>\n\n<|tts_bos|>"
+    )
+
+
+def test_unsupported_part_is_not_silently_discarded():
+    with pytest.raises(TemplateError, match="Unsupported MiniCPM-o content part"):
+        _compile_jinja_template(TEMPLATE.read_text()).render(
+            messages=[{"role": "user", "content": [{"type": "unknown"}]}],
+            add_generation_prompt=True,
+        )