[Refactor][Qwen3-TTS] Construct Code2Wav decoder natively (#2341)

Signed-off-by: Nick Cao <ncao@redhat.com>
Co-authored-by: Claude <noreply@anthropic.com>

tests/model_executor/models/qwen3_tts/test_qwen3_tts_code2wav.py

@@ -2,18 +2,25 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 from types import SimpleNamespace
+from unittest.mock import patch
 
 import pytest
 import torch
 import torch.nn as nn
 
-from vllm_omni.model_executor.models.qwen3_tts.qwen3_tts_code2wav import Qwen3TTSCode2Wav
+from vllm_omni.model_executor.models.qwen3_tts.qwen3_tts_code2wav import (
+    Qwen3TTSCode2Wav,
+)
 
 pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
 
+_NUM_QUANTIZERS = 2
+_TOTAL_UPSAMPLE = 4
+_OUTPUT_SAMPLE_RATE = 24000
+
 
 class _FakeDecoder(nn.Module):
-    def __init__(self, total_upsample: int = 4):
+    def __init__(self, total_upsample: int = _TOTAL_UPSAMPLE):
         super().__init__()
         self.total_upsample = total_upsample
 
@@ -24,18 +31,35 @@ class _FakeDecoder(nn.Module):
         return wav.view(1, 1, -1)
 
 
-def _make_model() -> Qwen3TTSCode2Wav:
-    model = Qwen3TTSCode2Wav(
-        vllm_config=SimpleNamespace(
-            model_config=SimpleNamespace(model="unused"),
-            device_config=SimpleNamespace(device=torch.device("cpu")),
-        )
+def _fake_dec_config():
+    return SimpleNamespace(
+        num_quantizers=_NUM_QUANTIZERS,
+        sliding_window=0,
     )
-    model._decoder = _FakeDecoder()
-    model._num_quantizers = 2
-    model._output_sample_rate = 24000
-    model._total_upsample = 4
-    model._ensure_speech_tokenizer_loaded = lambda: None
+
+
+def _make_model() -> Qwen3TTSCode2Wav:
+    dec_config = _fake_dec_config()
+    tok_config = SimpleNamespace(
+        decoder_config=dec_config,
+        output_sample_rate=_OUTPUT_SAMPLE_RATE,
+    )
+    with (
+        patch(
+            "vllm_omni.model_executor.models.qwen3_tts.qwen3_tts_code2wav.Qwen3TTSTokenizerV2Config.from_pretrained",
+            return_value=tok_config,
+        ),
+        patch(
+            "vllm_omni.model_executor.models.qwen3_tts.qwen3_tts_code2wav.Qwen3TTSTokenizerV2Decoder._from_config",
+            return_value=_FakeDecoder(),
+        ),
+    ):
+        model = Qwen3TTSCode2Wav(
+            vllm_config=SimpleNamespace(
+                model_config=SimpleNamespace(model="unused"),
+                device_config=SimpleNamespace(device=torch.device("cpu")),
+            )
+        )
     return model